Colon Cancer Guide

Anatomy of the Colon

The colon is an important part of the digestive system. It is structured into several parts and performs vital functions in the body. In humans, it is divided into several sections that perform different functions:

• Cecum: This is the beginning of the colon where the small intestine empties digested food into the colon. Attached to the cecum is the appendix, a small tube-shaped organ.
• Ascending Colon: This part moves upward from the cecum on the right side of the abdomen.
• Transverse Colon: As the name suggests, this part crosses the body from the right to the left side. It is enveloped by tissue called the mesocolon and is the longest part of the colon.
• Descending Colon: This section moves downward on the left side of the abdomen.
• Sigmoid Colon: Named for its S-shape, the sigmoid colon connects the descending colon to the rectum.
• Rectum: The final part of the colon leading to the anal canal where waste is expelled from the body.

Functions of the Colon

The colon plays several important roles in digestion, absorption, and waste elimination:

• Water Absorption: One of the main functions of the colon is to absorb water and salts from the remaining indigestible food matter. This process helps to solidify waste into feces.
• Fermentation: The colon contains a large number of bacteria that aid in the fermentation of unabsorbed material, particularly carbohydrates. These bacteria also produce essential vitamins such as vitamin K and some B vitamins, which are absorbed into the bloodstream.
• Fecal Storage and Transport: The colon stores feces until they are expelled from the body. It helps transport feces to the rectum through peristalsis, which is the wave-like contraction of muscles.
• Immune Function: The colon also plays a role in immunity. The bacteria in the colon help protect the body against harmful pathogens. The epithelium of the colon contains cells that contribute to its immune function.

About Colon Cancer

Colon cancer forms in the colon, which is approximately five and a half feet long. The first five feet of the colon are called the large intestine, and the rectum makes up the last six inches. Cancers found in both organs are often grouped together as colorectal cancer.

Colon cancer typically develops slowly over several years. It begins as a small abnormal growth on the inner lining of the colon called a polyp. Some polyps can eventually develop into cancer.

In many cases, colon cancer is confined to the colon. However, if left untreated, it can spread to other organs, most commonly the liver and lungs.

A small percentage of colon cancer is due to genetic causes that can be passed from parents to children.

Prevention of Colon Cancer

Lifestyle changes can reduce the risk of colon cancer. To lower your risk of colon cancer:

• Eat a variety of fruits, vegetables, and whole grains: Fruits, vegetables, and whole grains contain vitamins, minerals, fiber, and antioxidants that can help prevent cancer. Choose a variety of fruits and vegetables to get different vitamins and nutrients.
• Drink alcohol in moderation, if at all: If you choose to drink alcohol, limit the amount to no more than one drink a day.
• Quit smoking: Smoking is one of the most significant factors for developing cancers.
• Exercise at least 3 days a week: Aim for at least 30 minutes of exercise most days. If you haven’t been active, start slowly and gradually work up to 30 minutes. Also, consult a healthcare professional before starting an exercise program.
• Maintain a healthy weight: If you are at a healthy weight, work to maintain it by combining a healthy diet with daily physical activity. If you need to lose weight, seek guidance from a dietitian or other specialist who can recommend healthy ways to achieve your goal. Aim to lose weight slowly by consuming fewer calories and increasing physical activity.

Screening for Colon Cancer

If you are under 45 years old and have not been screened for colon cancer, it is especially important not to ignore symptoms. The recommended age to start screening for colon cancer is now 45 years. There has been a troubling rise in colon cancer among people in their 20s and 30s who have no history of the disease and few if any risk factors.

If you are under 45 years old and have concerning symptoms — especially rectal bleeding or blood in the stool — inform your doctor as soon as possible.

Types of Colon Cancer

The majority of colon cancers are a type called adenocarcinoma. This is cancer of the cells that line the inner surface of the colon. Rare types of tumors include:

• Carcinoid Tumors: These start in hormone-producing cells in the intestines.
• Gastrointestinal Stromal Tumors (GISTs): A type of soft tissue sarcoma that can be found anywhere in the gastrointestinal tract but rarely in the colon.
• Other Types of Sarcomas: These start in blood vessels or connective tissue of the colon.
• Lymphoma: A cancer of the immune system that more often begins in lymph nodes but can start in the colon.

Symptoms of Colon Cancer

Colon cancer often does not cause symptoms in its early stages. That’s why regular screenings for colon cancer are recommended based on your age, medical history, and other risk factors.

However, there are some signs of colon cancer that should not be ignored, such as:

• Rectal bleeding or blood in the stool
• Changes in bowel habits, such as diarrhea, constipation, or stool consistency lasting more than a few days
• Unexplained abdominal pain or cramps lasting more than a few days
• Persistent need to move the bowels that doesn’t go away after a bowel movement
• Unexplained weakness and fatigue
• Unintended weight loss
• Diagnosis of anemia

These symptoms do not necessarily mean you have colon cancer. Contact your doctor if any of these issues are severe or last longer than you think they should.

Risk Factors for Colon Cancer

Colon cancer is the second most common cause of cancer death in Bulgaria. It is also the second most common cancer in women and the most common in men.

Your risk of colon cancer depends on many factors. You can control some of these factors, but others you cannot, including:

• Age: The older you are, the more likely you are to develop colon cancer.
• Diet, Exercise, and Use of Tobacco and Alcohol: These lifestyle factors can influence your risk.
• Personal History of Polyps and Inflammatory Bowel Diseases: Including ulcerative colitis and Crohn's disease.
• Family History of Colon Cancer and Related Cancers: Including hereditary diseases such as Lynch syndrome and familial adenomatous polyposis (FAP).
• Genetics: About 5 to 10 percent of colon cancers are due to genetic causes passed from parents to children.

Genetic Causes of Colon Cancer

• Lynch Syndrome: Also known as hereditary non-polyposis colorectal cancer (HNPCC), it is associated with an increased risk of colon and rectum cancer, as well as endometrial, ovarian, stomach, urinary tract, brain, and pancreatic cancers. Lynch syndrome is the most common form of inherited colon cancer, responsible for about 3 percent of all colon and rectum cancers.
• Familial Adenomatous Polyposis (FAP): This involves many precancerous polyps, possibly hundreds or thousands, in the colon and rectum. In a milder form of FAP, there may be fewer polyps.
• MYH-Associated Polyposis (MAP): Characterized by multiple precancerous polyps in the colon and rectum, similar in number to those seen in the milder form of FAP.
• Hyperplastic Polyposis Syndrome (HPS): Involves the development of multiple hyperplastic polyps in the colon and rectum. Currently, no gene mutation associated with HPS is known.

Diagnosing Colon Cancer

If colon cancer is suspected, a specialist will perform a colonoscopy. This test removes a small piece of tissue to look for signs of cancer. A pathologist (a doctor who specializes in diagnosing diseases) examines this sample under a microscope.

If you are diagnosed with colon cancer, the next step is to determine how advanced the disease is. This is called staging. The medical team may recommend CT and MRI scans and other tests to see if the cancer has spread beyond the colon to other organs.

• Colonoscopy: Examines the inside of the entire length of the colon. It can usually be done on an outpatient basis and takes about an hour.
• Virtual Colonoscopy: Uses a CT scanner to take a series of X-rays, creating a three-dimensional picture of your intestines.
• Sigmoidoscopy: Examines the inside of the rectum and the part of the colon closest to the rectum (sigmoid colon). It is typically done on an outpatient basis.

Stages and Staging of Colon Cancer

The stages describe how widespread the cancer is in the colon and whether it has spread (metastasized) to other organs. This is important information for doctors when planning your care. There are five stages of colon cancer:

The stages describe how widespread the cancer is in the colon and whether it has spread (metastasized) to other organs. This is important information for doctors when planning your care. There are five stages of colon cancer:

• Stage 0: This very early cancer is found only in the innermost lining of the colon.
• Stage I: The tumor has spread beyond the inner lining but remains in the colon and has not spread to lymph nodes (small organs that are part of the immune system).
• Stage II: The cancer extends through the thick outer muscle layer of the colon but has not spread to lymph nodes.
• Stage III: The cancer has spread outside the colon to one or more lymph nodes.
• Stage IV: The cancer has spread to other parts of the body, such as the liver or lungs. This is known as metastatic cancer. The cancer may also be in the lymph nodes.

Treatment of Colon Cancer

If you are diagnosed with colon cancer, your doctors will discuss treatment options with you. To make an informed choice, ask about the pros and cons of each option, potential side effects, and how effective the treatment is.

There are several ways to treat colon cancer depending on the stage and location of the disease. These methods are often used in combination and include:

• Surgery to Remove the Cancer
• Chemotherapy: Using drugs that shrink or kill colon cancer cells.
• Radiation
• Targeted Therapy
• Immunotherapy

For more information on colon cancer treatment, visit this page.