What are the most common types of colorectal cancer. How are colorectal adenocarcinomas diagnosed and treated. What are the symptoms of gastrointestinal carcinoid tumors. How do rare forms of colorectal cancer differ from adenocarcinomas.

Understanding Colorectal Cancer: Types and Prevalence

Colorectal cancer is a term that encompasses cancers developing in the colon or rectum. While these cancers may be referred to separately as colon cancer or rectal cancer depending on their origin, they share many similarities and are often discussed together. The most prevalent form of colorectal cancer is adenocarcinoma, accounting for an impressive 95% of all cases.

Adenocarcinomas typically begin as polyps, which are abnormal tissue growths on the inner lining of the colon or rectum. A specific type of polyp called an adenoma has the potential to develop into cancer over time. This is why routine colonoscopies and polyp removal are crucial preventative measures in colorectal cancer screening.

Colorectal Adenocarcinoma Subtypes

While adenocarcinoma is the most common type, there are two less frequent subtypes worth noting:

• Mucinous adenocarcinoma: Comprising about 10-15% of colorectal adenocarcinomas, these tumors contain at least 60% mucus. The presence of mucus may lead to more aggressive spread and behavior compared to typical adenocarcinomas.
• Signet ring cell adenocarcinoma: This rare subtype accounts for less than 1% of colon cancers. Named for its distinctive appearance under a microscope, signet ring cell adenocarcinoma tends to be aggressive and may pose greater treatment challenges.

Recognizing Colorectal Adenocarcinoma Symptoms and Diagnostic Approaches

Colorectal adenocarcinoma can manifest through various symptoms, though it’s important to note that early-stage cancer may not cause noticeable signs. Common symptoms include:

• Abdominal pain and tenderness
• Blood in stool
• Changes in bowel habits (diarrhea or constipation)
• Thin stools
• Unexplained weight loss

Early detection through screening is crucial, as it can identify cancer before symptoms appear. Both the American Cancer Society and the U.S. Preventive Services Task Force recommend initiating colon cancer screening at age 45 for adults at average risk.

Diagnostic Process for Colorectal Cancer

The diagnostic journey for colorectal cancer typically begins with a colonoscopy, allowing doctors to visually inspect the colon and rectum. If suspicious areas are found, the process may include:

1. Biopsy: Removal of a small tissue sample for laboratory analysis
2. Blood tests: To assess overall health and potential cancer markers
3. Imaging studies: Such as CT scans or MRI to determine the extent of the cancer and whether it has spread

Treatment Options for Colorectal Adenocarcinomas

Once diagnosed, colorectal adenocarcinomas can be addressed through various treatment modalities, often used in combination for optimal outcomes. The primary treatment options include:

• Surgery: Removal of the tumor and surrounding tissue
• Chemotherapy: Use of drugs to kill cancer cells or stop their growth
• Radiation therapy: High-energy rays to destroy cancer cells
• Targeted therapy: Drugs designed to attack specific cancer cell features

The choice of treatment depends on factors such as the cancer’s stage, location, and the patient’s overall health. A multidisciplinary team of oncologists, surgeons, and other specialists typically collaborates to develop a personalized treatment plan.

Gastrointestinal Carcinoid Tumors: A Unique Subtype of Colorectal Cancer

Gastrointestinal carcinoid tumors represent a distinct category within colorectal cancers, belonging to a group known as neuroendocrine tumors (NETs). These tumors develop in specialized nerve cells called neuroendocrine cells, which play a role in hormone regulation.

Carcinoid tumors are characterized by slow growth and can occur in various parts of the body, including the lungs and gastrointestinal tract. In the context of colorectal cancer, they account for approximately 1% of all cases.

Symptoms of Gastrointestinal Carcinoid Tumors

The symptoms of carcinoid tumors can vary significantly depending on their location within the gastrointestinal tract:

• Appendix: Often asymptomatic unless blocking the appendix, potentially leading to appendicitis symptoms
• Small intestine or colon: May cause stomach cramps, pain, weight loss, fatigue, bloating, and other digestive issues
• Rectum: Can result in pain, bleeding, and constipation
• Stomach: Typically asymptomatic in early stages

The diverse and sometimes subtle nature of these symptoms underscores the importance of regular medical check-ups and prompt investigation of persistent gastrointestinal complaints.

Rare Forms of Colorectal Cancer: Beyond Adenocarcinomas

While adenocarcinomas dominate the landscape of colorectal cancers, several rare types exist, each with unique characteristics and treatment considerations. These uncommon forms include:

• Primary colorectal lymphomas
• Gastrointestinal stromal tumors (GISTs)
• Leiomyosarcomas
• Melanomas

These rare types collectively account for a small percentage of colorectal cancers but can present significant diagnostic and treatment challenges due to their uncommon nature.

Primary Colorectal Lymphomas

Lymphomas are cancers that originate in the lymphatic system. When they develop primarily in the colon or rectum, they’re classified as primary colorectal lymphomas. These rare tumors account for less than 1% of all colorectal malignancies.

Symptoms of primary colorectal lymphomas may mimic those of more common colorectal cancers, including abdominal pain, changes in bowel habits, and unexplained weight loss. However, their treatment approach differs significantly, often involving chemotherapy as the primary modality rather than surgery.

Gastrointestinal Stromal Tumors (GISTs)

GISTs are rare tumors that can occur anywhere in the gastrointestinal tract, including the colon and rectum. They develop from specialized cells in the wall of the GI tract called interstitial cells of Cajal.

While GISTs can be found in the colorectal region, they’re more common in the stomach and small intestine. Symptoms may include abdominal pain, gastrointestinal bleeding, and a palpable mass. Treatment often involves surgical removal and, in some cases, targeted therapy drugs.

Genetic Factors and Colorectal Cancer Risk

Genetic predisposition plays a significant role in colorectal cancer risk. Several inherited syndromes and gene mutations have been identified that increase an individual’s likelihood of developing colorectal cancer.

Lynch Syndrome

Also known as hereditary nonpolyposis colorectal cancer (HNPCC), Lynch syndrome is the most common inherited colorectal cancer syndrome. It’s caused by mutations in DNA mismatch repair genes and significantly increases the risk of colorectal and other cancers.

Individuals with Lynch syndrome have a 20-80% lifetime risk of developing colorectal cancer, compared to the general population risk of about 4-5%. They also tend to develop cancer at a younger age, often before 50.

Familial Adenomatous Polyposis (FAP)

FAP is a rare inherited condition characterized by the development of hundreds to thousands of precancerous polyps in the colon and rectum. Without intervention, individuals with FAP have a nearly 100% chance of developing colorectal cancer by age 40.

The condition is caused by mutations in the APC gene and is typically diagnosed through genetic testing and colonoscopy. Management often involves regular screening and, in many cases, preventive surgery to remove the colon before cancer develops.

Advancing Colorectal Cancer Research and Treatment

The field of colorectal cancer research is dynamic and rapidly evolving. Ongoing studies are exploring new treatment modalities, refining existing approaches, and deepening our understanding of the molecular basis of these cancers.

Immunotherapy Breakthroughs

Immunotherapy, which harnesses the body’s immune system to fight cancer, has shown promising results in certain types of colorectal cancer. Checkpoint inhibitors, a class of immunotherapy drugs, have been particularly effective in treating microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) colorectal cancers.

These therapies work by “releasing the brakes” on the immune system, allowing it to recognize and attack cancer cells more effectively. Ongoing research is focused on expanding the use of immunotherapy to a broader range of colorectal cancers and combining it with other treatment modalities for enhanced efficacy.

Targeted Therapies and Precision Medicine

The advent of targeted therapies has revolutionized colorectal cancer treatment. These drugs are designed to attack specific molecular targets that are crucial for cancer cell growth and survival. Examples include:

• EGFR inhibitors: For tumors without RAS mutations
• VEGF inhibitors: To block blood vessel formation in tumors
• BRAF inhibitors: For tumors with BRAF V600E mutations

The field of precision medicine aims to tailor treatment based on the genetic profile of an individual’s tumor. This approach allows for more personalized and potentially more effective treatment strategies.

Colorectal Cancer Prevention and Screening Innovations

Prevention and early detection remain crucial in the fight against colorectal cancer. While colonoscopy remains the gold standard for screening, new and less invasive methods are being developed and refined.

Stool-Based Tests

Advancements in stool-based tests have made colorectal cancer screening more accessible. These include:

• Fecal immunochemical test (FIT): Detects hidden blood in the stool
• Stool DNA test: Looks for both blood and specific DNA markers associated with colorectal cancer

While these tests are not as comprehensive as a colonoscopy, they offer a non-invasive option that can be done at home, potentially increasing screening rates.

Liquid Biopsies

Liquid biopsy is an emerging technology that detects cancer by analyzing biomarkers in blood samples. This method holds promise for early detection and monitoring of colorectal cancer, potentially offering a less invasive alternative to traditional biopsies.

Research is ongoing to refine liquid biopsy techniques and determine their optimal role in colorectal cancer screening and management.

As our understanding of colorectal cancer continues to grow, so do the options for prevention, detection, and treatment. From genetic testing to guide personalized screening plans, to innovative therapies targeting the molecular underpinnings of cancer, the field is advancing rapidly. While challenges remain, particularly in treating advanced and rare forms of colorectal cancer, the overall outlook for patients continues to improve.

The key to capitalizing on these advancements lies in awareness and action. Regular screening, adoption of healthy lifestyle habits, and prompt attention to potential symptoms are crucial steps that individuals can take to reduce their risk and improve outcomes. As research progresses, we can anticipate even more sophisticated and effective approaches to combating this common yet highly preventable form of cancer.

Most Common and Rare Forms

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science.

This page was updated on August 11, 2022.

Colorectal cancer develops in the colon or in the rectum. If it starts in the colon, it may be referred to as colon cancer. If it starts in the rectum, it may be called rectal cancer. Regardless of where they start, however, these cancers share a lot in common, which is why they’re together known as colorectal cancer.

The most common type of colorectal cancer is adenocarcinoma. Adenocarcinomas of the colon and rectum make up 95 percent of all colorectal cancer cases. In the gastrointestinal tract, rectal and colon adenocarcinomas develop in the cells of the lining inside the large intestine. These adenocarcinomas typically start as a growth of tissue called a polyp. A particular type of polyp called an adenoma may develop into cancer. Colorectal polyps are often removed during a routine colonoscopy before they may turn cancerous.

While other types of tumors may develop in the colon or rectum, they’re much more rare. Less common types of colorectal cancer include:

• Primary colorectal lymphomas
• Gastrointestinal stromal tumors
• Leiomyosarcomas
• Carcinoid tumors
• Melanomas

This article will cover:

• Types of colorectal cancer
• Rare types of colorectal cancer
• Genetic risks

Types of colorectal cancer

Colorectal adenocarcinoma

“Adeno” is a prefix meaning gland. “Carcinoma” is a type of cancer that grows in epithelial cells, which line the surfaces inside and outside the body. Adenocarcinomas develop in the lining of the large intestine (colon) or the end of the colon (rectum). They often start in the inner lining and spread to other layers.

There are two less common subtypes of adenocarcinomas:

• Mucinous adenocarcinoma is made up of about 60 percent mucus. The mucus may cause cancer cells to spread more quickly and become more aggressive than typical adenocarcinomas. Mucinous adenocarcinomas account for 10 percent to 15 percent of all rectal and colon adenocarcinomas.
• Signet ring cell adenocarcinoma accounts for fewer than 1 percent of all colon cancers. Named for its appearance under a microscope, signet ring cell adenocarcinoma is typically aggressive and may be more difficult to treat.

Most information about colorectal cancer refers to colorectal adenocarcinoma, the most common type. Estimates suggest that 4.1 percent of people may develop colorectal cancer during their life, according to the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program.

Colorectal adenocarcinoma symptoms generally include:

• Abdominal pain and tenderness
• Blood in stool
• Changes in bowel habits, such as diarrhea or constipation
• Thin stools
• Unexplained weight loss

Getting screened for colon cancer may detect the disease before it starts causing symptoms. The American Cancer Society (ACS) and the U.S. Preventive Services Task Force both recommend adults start colon cancer screening at age 45.

Diagnosing colorectal cancer starts with a colonoscopy, which lets doctors see inside the rectum and colon. If signs of colorectal cancer are discovered during a colonoscopy, other tests will follow. A biopsy may be performed, which involves removing a small piece of potentially cancerous tissue (sometimes during a colonoscopy) and analyzing the sample for the presence of cancer. Once a diagnosis is confirmed by a colonoscopy and a biopsy, blood tests and imaging tests, such as computed tomography (CT) scans and magnetic resonance imaging (MRI) scans, may be used to help learn more about the cancer and whether it’s spread.

Common treatment options for colorectal adenocarcinomas include:

• Surgery
• Chemotherapy
• Radiation therapy
• Targeted therapy

Gastrointestinal carcinoid tumors

Carcinoid tumors develop in nerve cells called neuroendocrine cells, which help regulate hormone production. These tumors are among a group of cancers called neuroendocrine tumors (NETs). Carcinoid tumor cells are slow-growing and may develop in the lungs and/or gastrointestinal tract. They account for about 1 percent of all colorectal cancers and half of all cancers found in the small intestine.

Potential symptoms differ depending on where the tumor grows. A carcinoid tumor in the appendix typically doesn’t cause symptoms, unless it begins to block the pathway from the appendix to the intestine, leading to appendicitis symptoms such as fever, nausea and vomiting.

Tumors in the small intestine or colon may cause stomach cramps and pain, weight loss, tiredness, bloating and other stomach problems. Carcinoid tumors in the rectum may cause pain, bleeding and constipation. In the stomach, carcinoid tumors typically don’t cause symptoms.

Carcinoid tumors also sometimes produce hormones that may lead to various symptoms, depending on the type of hormone. For example, 10 percent of people with these tumors may experience flushing in the face, diarrhea, wheezing and rapid heartbeat due to certain hormone-like substances that are released by the tumor, according to the ACS.

Depending on where they develop, gastrointestinal carcinoid tumors may be discovered in various ways. For example, a tumor in the appendix may be found after it causes appendicitis, and the appendix is removed. Rectal tumors may be detected during routine checkups.

Several tests are used to diagnose carcinoid tumors in the abdominal tract, including blood tests, urine tests, imaging scans, endoscopy and colonoscopy.

Gastrointestinal carcinoid tumor treatment options include:

• Surgery
• Radiation therapy
• Chemotherapy
• Hormone therapy

Rare types of colorectal cancer

Other types of rare colorectal cancers combined account for less than 5 percent of all cases:

Primary colorectal lymphomas

A type of non-Hodgkin lymphoma, this cancer type develops in the lymphatic system, specifically in cells called lymphocytes. Lymphocytes are a type of white blood cell that helps the body fight infections. Lymphoma may develop in many parts of the body, including the lymph nodes, bone marrow, spleen, thymus and the digestive tract. Primary colorectal lymphomas account for 0.5 percent of all colorectal cancers and about 5 percent of lymphomas. This colorectal cancer type usually develops later in life and is more common in men.

Symptoms may include indigestion, bloating, unexplained weight loss, stomach pain, vomiting, diarrhea and other stomach issues. Diagnosis may involve biopsy and endoscopy.

Treatment options vary but may include:

• Chemotherapy
• Radiation therapy
• Surgery

Gastrointestinal stromal tumors

Gastrointestinal stromal tumors are a rare type of colorectal cancer that forms in special cells found in the lining of the gastrointestinal (GI) tract called interstitial cells of Cajal (ICCs). More than 50 percent of GISTs develop in the stomach. While most other GISTs form in the small intestine, the rectum is the third most common location. GISTs are classified as sarcomas, or cancers that begin in the connective tissues, which include fat, muscle, blood vessels, deep skin tissues, nerves, bones and cartilage.

While estimates are uncertain, about 4,000 to 6,000 cases of GIST are diagnosed in the United States every year, according to the ACS. These tumors tend to take a while to grow large enough to start causing symptoms. However, they may cause bleeding in the gastrointestinal tract. Depending on the location of the tumor, blood may show up in vomit or bowel movements. Over time, slow bleeding may lead to a decrease in the amount of red blood cells, a condition called anemia, which causes fatigue and weakness.

Other potential symptoms include:

• Abdominal pain
• Abdominal mass or lump
• Nausea
• Vomiting
• Poor appetite
• Weight loss
• Swallowing problems

The diagnostic process may involve an endoscopy, colonoscopy, biopsy and various imaging tests.

Some smaller GISTs may not need to be treated right away, while others are typically treated with surgery and targeted therapy.

 Colon and rectal leimyosarcomas

Another form of sarcoma, leiomyosarcoma essentially means “cancer of smooth muscle.” The colon and rectum have three layers of the type of muscle affected by leiomyosarcoma, and all three work together to guide waste through the digestive tract. This rare type of colorectal cancer accounts for about 0.1 percent of all colorectal cases.

In the early stages, leiomyosarcomas in the colon or rectum may not cause symptoms. As the cancer progresses, symptoms may include fatigue, weight loss, vomiting blood, changes in stools and other stomach problems. Diagnosis generally includes standard measures, such as a biopsy, blood tests and imaging tests. Treatment typically starts with surgery to remove the tumor. Other treatment options include radiation therapy and chemotherapy.

Colon and rectal melanomas

Most commonly associated with skin cancer, these may start to develop anywhere, including in the colon or rectum, or may spread to the GI tract from the primary melanoma site. Melanomas account for 1 percent to 3 percent of all cancers that develop in the digestive system, according to research published in BMJ Case Reports. How melanomas develop in the colon isn’t well understood, as it’s extremely rare. Diagnosis may involve a biopsy and other tests to determine whether the cancer spread from elsewhere in the body or started in the colon or rectum.

Colorectal melanoma treatment may include:

• Surgery
• Immunotherapy
• Chemotherapy
• Radiation therapy

Colorectal squamous cell carcinoma

This cancer, also known as SCC, is extremely rare in the colon, with fewer than 100 cases reported in the literature as of a 2017 case report in the Journal of Community Hospital Internal Medicine Perspectives. Squamous cell carcinoma is typically associated with skin cancer—it’s the second most common type of skin cancer. Squamous cells are a particular type of cell present in many areas of the body. Squamous cell carcinoma occurs when these cells start growing uncontrollably and become cancerous. The reason why this rarely occurs in the colon and rectum isn’t well understood.

Symptoms may resemble colorectal adenocarcinoma, including stomach issues and changes in stool or bowel habits. Colonoscopy and other tests are used to diagnose this cancer. It’s important to determine whether the cancer started in the colon or rectum, or whether it spread to this region from another area of the body. Treatment isn’t standardized but may include surgery, chemotherapy and radiation therapy.

Familial adenomatous polyposis (FAP)

This accounts for about 1 percent of all cancers in the colon or rectum, according to the ACS. People with this syndrome may develop hundreds or even thousands of colon or rectal polyps. These polyps tend to occur when people with this syndrome are 10 to 12 years old. Nearly all people with FAP develop colorectal cancer during their lifetime, and as a result, some people have their colon removed as a preventative measure.

Genetic risks

If an inherited syndrome associated with colorectal cancer is suspected, the patient may consider undergoing genetic testing. Genetic testing involves taking a sample of blood, hair or other bodily fluids to analyze for DNA mutations linked to cancer or a genetic syndrome. The patient also may be advised to get regular colonoscopies to look for colorectal cancer and to begin screening early.

Peutz-Jeghers syndrome (PJS): This condition causes a particular type of polyp to develop in the gastrointestinal tract, called a hamartoma. This syndrome is inherited from one’s parents and is caused by mutations in a particular gene (STK11). It comes with an increased risk of colorectal cancer and others including breast cancer, ovarian cancer and pancreatic cancer. If colorectal cancer does occur in individuals with PJS, it tends to develop at a younger than average age.

Familial colorectal cancer: Some people inherit genetic syndromes from their parents that increase their risk of getting colorectal cancer. These syndromes come with mutations—in particular, genes that make it more likely that cancer will develop. Examples include Lynch syndrome, familial adenomatous polyposis and other rarer syndromes. Lynch syndrome is associated with about 2 percent to 4 percent of all cancers in the colon or rectum, according to the ACS. People with Lynch syndrome have a high risk of getting colorectal cancer at some point in their lifetime—up to 50 percent. Those who have Lynch syndrome and go on to develop colorectal cancer tend to get the cancer at an earlier than average age.

Does it matter if colon cancer is on the left or right side? | Roswell Park Comprehensive Cancer Center

Roswell Park’s new colon and rectal surgeon, Anthony Dakwar, MD, explains the differences between colon cancers that arise in the right side of the colon compared to those in the left side.

Yes, it does. Several differences can be seen in the colon cancers that begin on the left side, in the descending and sigmoid parts of the colon, compared to those that occur on the right side, in the ascending and cecum portions of the colon, explains Roswell Park Comprehensive Cancer Center’s new colon and rectal surgeon Anthony Dakwar, MD. (Cancers can also develop in the middle, transverse section of the colon, although less commonly.)

The location in the colon where cancer develops is one of the factors that’s considered when developing your customized treatment plan.

The differences between left-sided and right-sided colon cancers include why and how the cancer developed, whether it produces noticeable symptoms, and the cancer’s aggressiveness and how well it responds to usual chemotherapy regimens. “While polyps can occur anywhere in the entire colon, their incidence and their predisposition to turn into cancer can differ depending on where in the colon they arise,” says Dr. Dakwar

Left-sided colon cancers are often ordinary

The cancers that develop on the colon’s left side are more likely to be unremarkable, garden-variety colorectal cancers. These tend to develop in a traditional pathway, Dr. Dakwar explains. “Simple colon polyps, abnormal growths of tissue, experience a sporadic chromosomal change in their cells that, in time, can convert into a cancerous tumor. This process is slow and can take several years, which is why screening with colonoscopy can be performed at several-year intervals.”

Right-sided colon cancers are more unusual

Polyps that develop in the right side of the colon are more likely to occur in people with a genetic predisposition for developing cancer, such as Lynch Syndrome and microsatellite instability. Right-sided polyps are more likely to develop into cancers — which often grow rapidly and have a higher risk for metastasis, spreading to distant body areas.

Right-sided colon cancers also tend to develop from flat polyps rather than the usual mushroom-shaped ones, and are genetically atypical, too. “Differences in the genetic makeup of these tumors often means these cancers are more aggressive and can be resistant to current chemotherapy treatment regimens,” he says.

Both types need multidisciplinary care

The location of your cancer is just one aspect of it that’s contemplated in developing your treatment plan. “For both left- and right-sided colon cancers, unless they are metastatic, upfront surgery is the typical first-line treatment,” says Dr. Dakwar. “However, the key to having successful treatment is a multidisciplinary approach with regards to obtaining personalized and individualized cancer care.” At Roswell Park, your care team will include physicians from various medical disciplines — surgical, medical and radiation oncologists, plus gastroenterologists and pathologists — each bringing their respective expertise to the table.

“Our team ensures that every patient gets evaluated systematically and receives a customized treatment plan. We are able to get patients on cutting-edge clinical trials in order to enhance their treatment plan and provide opportunity for being cancer-free.”

Don’t wait for symptoms — get your screening!

Screening tests look for signs of cancer before it progresses to the point where symptoms may arise. Abdominal symptoms such as pain, bloating or rectal bleeding are often signs of an abnormal process in the left side of your colon. “Right-sided colon cancers tend to be asymptomatic or cause these symptoms only when they are at an advanced stage and fairly large. Right-sided cancers are more likely to be diagnosed at a later stage and this alone makes for a poorer prognosis,” Dr. Dakwar says.

The good news is that screening with colonoscopy can detect polyps and early cancers anywhere in the colon. Getting a colonoscopy screening on time, according to the recommended guidelines, can find and treat precancerous polyps and prevent cancer from forming. “There is no other screening test that can substitute for a colonoscopy,” says Dr. Dakwar.

What is “on time” for your colonoscopy? Most people at average risk should begin regular colon and rectal screening at age 45. But several factors mean you should begin sooner, such as being African American or having a family history of gastrointestinal cancer. Talk to your healthcare provider to learn when you need to schedule your screening.

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symptoms, stages, prognosis, survival, diagnosis, treatment of sigmoid colon cancer

Contents

• Causes and risk factors
• Signs of cancer of the sigmoid colon
• Types of sigmoid colon cancer
  • Histological classification
  • Growth classification
  • TNM classification and stages
  • ICD-10 code
• Diagnosis of oncology of the sigmoid colon
• Treatment of sigmoid colon cancer
• Prognosis in cancer of the sigmoid colon
• Prophylaxis

Sigmoid colon cancer is a malignant tumor of the intestine that grows from mucosal epithelial cells. Among all oncological diseases of the intestine, it ranks third, and is diagnosed in 34% of patients. The predominant number of cases is in the age group of 40-60 years, men get sick 1.5 times more often than women. At the initial stage, cancer does not give symptoms, so early diagnosis is possible only with the help of regular screening. The progression of the disease is accompanied by metastasis of the tumor to other parts of the intestine, liver, lungs. Given the small number of early diagnosed cases, cure for sigmoid colon cancer is possible only in 50-60% of patients. The median five-year survival rate is 65%. Treatment of sigmoid colon cancer is carried out by surgical methods, radiation and targeted therapy, chemotherapy.

Causes and risk factors for the development of sigmoid colon cancer

The cause of atypical degeneration of epithelial cells of the intestinal mucosa is the negative influence of external and internal factors. The anatomical features of the sigmoid colon increase the risk of malignancy. The intestine has an S-shape, which is why feces move more slowly through it. This leads to a longer contact with the mucosa of carcinogenic food products. The longer this contact, the higher the likelihood of malignancy of epithelial cells.

Causes and risk factors for the development of sigmoid colon cancer:

• sedentary work, low physical activity;
• predominance in the diet of fried, spicy foods, products of animal origin;
• chronic bowel disease;
• anomalies of intestinal development;
• chronic constipation;
• alcohol abuse, smoking;

90,005 cases of colorectal cancer in the family;

• colon polyps;
• unfavorable ecological situation;
• harmful production factors.

Symptoms of sigmoid colon cancer

The initial stage of sigmoid colon cancer, until the tumor has reached a large size, proceeds without obvious symptoms. As the neoplasm grows, the patient complains of:

• weakness, excessive fatigue;
• rumbling, bloating;
• alternating diarrhea and constipation;
• pain in the lower abdomen;
• mucus in stool, discoloration;
• nausea, loss of appetite.

When the first signs of sigmoid colon cancer appear, you should contact your general practitioner or proctologist. Laboratory and instrumental examination reveals the disease at an early stage, when the most sparing surgical treatment can be dispensed with.

When the tumor reaches a large size, begins to disintegrate, signs of intestinal obstruction appear. Constipation begins to predominate in the patient up to the complete absence of stool, feces acquire a ribbon-like or pea-like shape. Blood and pus appear in the feces. Pain in the abdomen bothers a person more and more often, they have a cramping character.

Advanced cancer leads to severe intoxication. Cancer patients have a characteristic appearance:

• gray-earthy skin color;
• weight loss up to cachexia;
• large belly and thin limbs.

When metastases spread to other organs, symptoms appear that indicate a violation of their function. Metastasis of a malignant neoplasm occurs in three ways:

• lymphogenous – through the lymphatic vessels and nodes;
• hematogenous – with the blood flow, atypical cells are carried to different organs, most often to the lungs, liver, bones;
• implantation – a tumor that has sprouted into the intestinal wall passes to the mesentery, fiber, and peritoneum located nearby.

Classification of cancer of the sigmoid colon

Tumors of the sigmoid colon are classified by cellular origin:

• adenocarcinoma is the most common variant, it is formed from cells of the glandular epithelium, the severity of the course depends on the degree of differentiation of atypical cells;
• cricoid cell carcinoma is a rare form, formed by mucinous cells, characterized by an unfavorable course;
• mucoid cancer – formed by mucinous cells, characterized by low differentiation, rapid growth and metastasis.

Classification according to the nature of tumor growth includes two options – exophytic and endophytic. An exophytic tumor is similar to a polyp with a stalk, growing into the intestinal lumen. Endophytic cancer spreads inside the intestinal wall, has an annular shape.

Classification by TNM and stage

The TNM classification of sigmoid colon cancer generally accepted in oncology takes into account the size of the primary tumor, metastases of lymph nodes and other organs:

• Tis – the beginning of the formation of a malignant process, damage to the mucosal lamina propria;
• T0 – defeat of the entire submucosal layer;
• T2 – damage to the muscle layer;
• T3 – germination of the tumor throughout the intestinal wall, spreading into the fiber;
• T4 – tumor invasion of surrounding tissues;
• N0 – no damage to the lymph nodes;
• N1 – metastasis to 1-3 nearest lymph nodes;
• N2 – defeat of more than 3 regional lymph nodes;
• M0 – no metastases;
• M1a – metastases in one organ;
• M1b – metastases in several organs;
• M1c – metastasis in the peritoneum.

The following stages of sigmoid colon cancer are distinguished:

• 1 – the tumor is not more than 2 cm, does not extend beyond the mucosa, does not give metastases;
• 2A – formation up to 5 cm, germinates the intestinal wall, does not give metastases;
• 2B – the same as in 2A, but with metastases to the nearest lymph nodes;
• 3A – mass more than 5 cm, metastases to the nearest lymph nodes;
• 3B – widespread tumor with metastases to distant lymph nodes;
• 4A – the tumor blocks the intestinal lumen, metastasizes with blood flow to other organs;
• 4B – spread of cancer to nearby organs with the formation of fistulas, multiple metastasis.

Disease stages according to TNM classification:

• 0 — Tis, N0, M0;
• 1 – T1-2, N0, M0;
• 2 – T3-4, N0, M0;
• 3 – T1-4, N1-2, M0;
• 4 – T any, N any, M0.

ICD-10 code

ICD 10 code for sigmoid colon cancer (International Classification of Diseases) – C18. 7.

Diagnosis of oncology of the sigmoid colon

Diagnosis of cancer of the sigmoid colon is carried out by a coloproctologist. When communicating with the patient, the doctor specifies the nature of health complaints, the conditions for their occurrence and the duration of their existence. With a digital examination of the rectum, the proctologist cannot detect the tumor itself, since it is located much higher. However, traces of blood and pus remain on the glove, which indicates a pathological process in the intestines.

Instrumental and laboratory methods are used to clarify the diagnosis of sigmoid colon cancer. Blood and urine tests indirectly indicate oncopathology:

• moderate or severe anemia;
• increase in ESR and CRP;
• increased liver enzymes;
• vitamin B deficiency;
• bleeding disorder;
• blood in feces.

Imaging methods allow determining the exact position of the tumor, its size and metastasis:

• sigmoidoscopy, colonoscopy allow the doctor to visually assess the condition of the sigmoid colon mucosa, the size and nature of tumor growth, and also take a tissue sample for histological examination;
• computed tomography provides more accurate information about the prevalence of neoplasm in the intestine;
• radiography, ultrasound and magnetic resonance imaging help to identify immediate and distant metastases.

Histological examination provides information about the cellular origin of the tumor, helps to plan treatment and predict the chances of recovery.

Treatment of sigmoid colon carcinoma

An effective and reliable method of cancer treatment is surgery. Removal of part of the intestine with a tumor and adjacent tissues gives a high chance of a full recovery. However, this method works only at stages 1 and 2A of the disease, until the tumor has metastasized. It is extremely rare to detect cancer at these stages, therefore, in most cases, the patient must be treated in combination. Surgical intervention is combined with radiation and targeted therapy, chemotherapy.

During the operation, the surgeon removes the cancerous part of the sigmoid colon, mesentery and adjacent tissue with lymph nodes. The volume of intervention depends on the prevalence and localization of the pathological process. A prerequisite is the removal of 5 cm of apparently unchanged tissue on both sides of the tumor. This is the prevention of the preservation of atypical cells and the recurrence of the disease in the future.

It is important not only to remove the tumor, but also to restore the anatomical structure of the intestine for its full functioning. With a small size of the neoplasm, the surgeon forms an intestinal anastomosis immediately. Such an operation is called a single-stage operation. In severe cases with a large amount of tissue removed, the surgeon first brings the colostomy to the anterior abdominal wall. Anastomosis is formed after a few months, such an operation is called a two-stage operation.

Before and after surgery, the patient receives radiation therapy and chemotherapy. The purpose of their appointment before the operation is to reduce the size of the neoplasm, to suppress the reproduction of atypical cells. After surgery, radiation therapy and chemotherapy destroy the remaining cancer cells and affect distant metastases.

Chemotherapy is used as an independent method of treatment in patients with inoperable tumors, as well as in patients with contraindications to surgery.

Inoperable patients with sigmoid colon cancer undergo palliative therapy, which increases life expectancy and improves its quality:

• irradiation;
• operations to restore bowel function;
• analgesics;
• treatment of concomitant diseases.

Sigmoid colon cancer: prognosis

The prognosis for life and recovery in sigmoid colon cancer depends on the histological type of neoplasm, stage, timely diagnosis and treatment. The median five-year survival rate after combined treatment is 65%. Sigmoid colon carcinoma has a better prognosis than cricoid and mucosal carcinoma.

If treatment for sigmoid colon cancer was started at stage 1, then 5 years or more live 95% of patients. The prognosis for stage 2-3 sigmoid colon cancer is a five-year survival period in 30-50% of patients. At stage 4, five-year survival is possible only in 8%. This is why regular check-ups with colonoscopy are so important. People at risk for developing cancer should be screened annually.

Cancer of the sigmoid colon is completely curable at the first stage; for this, surgical removal of the neoplasm with part of the intestine is used. Starting from the second stage, the effectiveness of treatment decreases, a complete cure cannot be achieved already at stages 3B-4.

Prevention of cancer of the sigmoid colon

Prevention consists in timely detection and removal of risk factors:

• obligatory removal of all intestinal polyps, as they are absolutely precancerous conditions;
• annual examination of people over 40 for fecal occult blood, colonoscopy;
• rational, healthy diet with restriction of carcinogenic products;
• daily intake of fiber in the form of fresh fruits and vegetables;
• prevention of constipation;
• adequate exercise;
• cessation of smoking, alcohol.

Sources:

1. Zakharenko A.A. Staged surgical treatment of a patient with complicated locally advanced cancer of the sigmoid colon / A. A. Zakharenko [et al.] // Bulletin of Surgery. – 2015. – No. 1. – S. 67-70.
2. Demidov S.M. Colorectal cancer and rectal cancer / S.M. Demidov // Textbook. – 2016. – S. 6-36.
3. Davydov M.I. Oncology / M.I. Davydov, Sh.Kh. Gantsev // Textbook. – 2010. -S. 920.
4. Burtsev D.V. The effectiveness of screening for colon tumors on the basis of the regional consultative and diagnostic center / D.V. Burtsev // PM. – 2012. – No. 2. – S. 214-217.

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The information in this article is provided for reference purposes and does not replace the advice of a qualified professional. Do not self-medicate! At the first sign of the disease, you should consult a doctor.

Tumor of the sigmoid colon: cancer of the sigmoid colon, treatment, prognosis, symptoms of oncology of the sigmoid colon In oncology, malignant neoplasms of this localization are called cancer of the rectosigmoid junction.

Together with colon cancer, they are united under the general name of colorectal cancer.

In the vast majority of cases, a malignant tumor of the sigmoid colon is represented by adenocarcinoma. It accounts for 90-95% of all identified malignant neoplasms. The rest of the tumors are represented by the following variants:

• Signet cell.
• Small cell.
• Squamous.
• Medullary.
• Undifferentiated.

Risk group

Currently, several risk factors have been identified, the presence of which increases the likelihood of developing cancer of malignant neoplasms in the sigmoid colon. These include:

Dietary habits

The following dietary habits increase the risk of developing colorectal cancer:

• Excessive consumption of animal fats and red meat.
• Insufficient content of vegetable fiber in the diet.
• Regular consumption of alcohol.
• Excess power.

Vegetarians have been shown to be an order of magnitude less likely to be diagnosed with colorectal cancer than people with a standard diet. For some time, it was even considered that meat is the main carcinogen for the intestines and leads to the formation of malignant tumors. The modern theory is based on the fact that vegetable fibers, which are rich in the diet of vegetarians, cleanse the intestines and do not allow its contents to stagnate. This reduces the contact of the intestinal epithelium with carcinogens and prevents its malignant transformation.

The second risk factor is the presence of polyps . In the vast majority of cases, bowel cancer develops as a result of malignancy of adenomatous polyps. Moreover, the longer it exists and the larger its size, the more likely its malignant degeneration.

Heredity . The role of hereditary predisposition has been proven in relation to two syndromes: familial adenomatous polyposis (FAP) and Lynch syndrome – hereditary non-polyposis colon cancer. The share of hereditary cancer accounts for 5-7% of cases of malignant tumors of cancer of this localization.

Other risk factors:

• Inflammatory bowel disease – ulcerative colitis, Crohn’s disease.
• History of breast and ovarian cancer.
• Immunodeficiency diseases.

Symptoms

The insidiousness of malignant tumors of the sigmoid colon lies in the fact that in the initial stages there are no signs of the disease. The clinical picture unfolds when the process goes into stage 3-4.

At the same time, general and local symptoms are distinguished. Of the general ones, weight loss, chronic fatigue, increased fatigue, pallor and pastosity of the skin (against the background of chronic iron deficiency anemia) are noted.

Local symptoms include:

• Abdominal pain. Pain can have various causes, from impaired intestinal motility to tumor growth into adjacent tissues and organs.
• Violation of the regularity of the chair. Patients are concerned about chronic constipation, which are replaced by fetid diarrhea. This is due to the fact that feces accumulate above the location of the tumor, which, in turn, leads to an increase in the processes of fermentation and putrefaction, the intestinal contents liquefy, and constipation is replaced by diarrhea. Due to inflammation of the intestinal wall and injury to the tumor, there may be blood streaks in the stool. When obturation (blockage) of the intestinal lumen by a tumor develops intestinal obstruction, which is accompanied by cramping pain, bloating, an increase in symptoms of intoxication, nausea and vomiting. This condition requires emergency hospitalization from a surgical hospital for immediate medical care.

In addition, signs of sigmoid colon cancer can be:

• Increased gas formation.
• Nausea and bloating.
• Discharge from the anus of mucus, blood or pus.

Staging and classification of sigmoid colon cancer

According to the type of tumor growth, exophytic and endophytic cancer are distinguished. Exophytic tumors grow into the intestinal lumen and look like nodules or outgrowths. If they grow excessively, they can obstruct the intestinal lumen, causing intestinal obstruction.

Endophytic or infiltrative form of cancer is characterized by the fact that it grows in the thickness of the intestinal wall. The tumor can cover the intestinal wall circularly, narrowing its lumen, which also causes intestinal obstruction.

Staging of the disease is carried out on the basis of data on the degree of spread of the tumor:

• cancer in situ – malignant cells are found only in the surface layer of the intestinal mucosa.
• Stage 1 – the tumor invades the intestinal mucosa and reaches the submucosa and muscle layer.
• stage 2 – cancer infiltrates the entire intestinal wall and can go beyond it, but does not yet give metastases.
• stage 3 – metastases appear in regional lymph nodes. The tumor can be of any size.
• Stage 4 – there are distant metastases, or the tumor spreads along the peritoneum (peritoneal carcinomatosis).

Metastasis

The following methods of metastasis are typical for malignant tumors of the sigmoid colon:

• Lymphogenic – through the lymphatic vessels, malignant cells first reach the regional lymph nodes, and then spread further, to more distant groups. For example, supraclavicular nodes may be affected.
• Hematogenous route – malignant cells spread through the blood vessels. The liver and lungs are the first to be affected. If the patient has undifferentiated cancer, metastases to the bone marrow may occur.
• Implantation metastasis – when the tumor goes beyond the intestinal wall, nearby organs and tissues can be affected. In this way, multiple peritoneal metastases, or peritoneal carcinomatosis, are formed.

Diagnosis of sigmoid colon cancer

The most informative method for diagnosing sigmoid colon cancer is colonoscopy with biopsy. The procedure involves a complete examination of the entire surface of the colon using a special endoscopic technique.

A shortened version of colonoscopy is rectosigmoidoscopy, which only looks at the final stage of the colon, the rectum and sigmoid colon.

Both diagnostic methods make it possible to detect a tumor of the sigmoid colon, assess its size, the likelihood of complications, and take a piece of tissue for subsequent histological examination. To obtain enough material to verify the tumor, a biopsy is taken from several points. The results obtained are necessary for treatment planning.

If it is impossible to perform a total colonoscopy at the diagnostic stage, it must be done within 3-6 months after the operation, since there is a risk of synchronous malignant neoplasms that are localized in areas inaccessible during rectosigmoscopy. If even after the operation a total colonoscopy is not possible, CT colonography or barium enema is performed.

As part of a clarifying diagnosis, a CT scan of the abdominal cavity and chest is performed. This study will allow to differentiate the stage of the disease and detect regional and / or distant metastases. CT can be partially replaced by ultrasound of the pelvic organs, abdominal cavity and retroperitoneal space.

Treatment

The key treatment for malignant tumors of the sigmoid colon is radical surgical removal. In the early stages (stages 1-2), it is recommended to give preference to sparing, minimally invasive endoscopic operations. In other cases, resection of the sigmoid colon is indicated within healthy tissues, departing from the edge of the tumor by at least 5 cm. Also, tumor-affected tissues, in particular, regional lymph nodes, are removed as a single block. The radical nature of the operation must be confirmed by an urgent histological examination for the presence of tumor cells in the cut-off edges.

Radical surgical treatment can be carried out in 1 or 2 stages. In a one-stage operation, the tumor is removed with the restoration of the integrity of the intestine by applying an anastomosis.

If this is not possible, two-stage operations are carried out. After removal of the tumor, the adducting section of the intestine is removed to the anterior abdominal wall (a colostomy is formed through which the bowel will be emptied), and a few months later, after the end of treatment, reconstructive operations are performed and the colostomy is removed.

If radical tumor resection is not possible, consider perioperative chemotherapy to shrink the tumor and make it resectable. If this does not happen, palliative operations are performed, and the main treatment of the patient is carried out through chemotherapy.

If there are distant metastases, they are also recommended to be removed surgically. Preference is given to simultaneous operations, when the primary focus and metastases are removed during one operation. If the metastases are unresectable, chemotherapy is performed and then the option of their surgical removal is re-considered.

Chemotherapy for sigmoid colon cancer

Chemotherapy for sigmoid colon cancer can be used as part of combination therapy. In addition, it can be used as an independent method of therapy for unresectable tumors or when it is impossible to perform an operation due to the presence of general contraindications.

Combination treatment includes adjuvant chemotherapy. The expediency of its appointment is determined based on the stage of the tumor and the results of an urgent intraoperative study of the removed fragment of the intestine for the presence of malignant cells.

As part of adjuvant chemotherapy, fluoropyrimidine therapy (5-fluorouracil, then 5 FU) is used together with 3rd generation platinum drugs (oxaliplatin). If the patient develops severe complications on two-component regimens, therapy is continued with fluoropyrimidines in mono mode. The goal of adjuvant chemotherapy is to destroy the remaining tumor cells and prevent the development of relapses of the disease.

Self-administered chemotherapy is palliative in nature and is aimed at containing the tumor process, prolonging the patient’s life and improving its quality.