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Colorectal Cancer: Colon and Rectal Cancers

Disabled World: Revised/Updated: 2019/04/26

Synopsis: Colorectal cancer, also called colon cancer or large bowel cancer, includes cancerous growths in the colon, rectum and appendix. Colorectal cancer is the 3rd most common form of cancer and 2nd leading cause of cancer related death in the Western world. A diet high in red, processed meat, while low in fiber increases the risk of colorectal cancer.


Main Document

Defining Colorectal Cancer

Colorectal cancer (also known as colon cancer, rectal cancer or bowel cancer) is the development of cancer in the colon or rectum (parts of the large intestine). It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Colon cancer is cancer of the large intestine (colon), the lower part of your digestive system. Rectal cancer is cancer of the last several inches of the colon. Together, they're often referred to as colorectal cancers. Signs and symptoms may include blood in the stool, a change in bowel movements, weight loss, and feeling tired all the time.

With 655,000 deaths worldwide per year, it is the third most common form of cancer and the second leading cause of cancer-related death in the Western world, and the second leading cause of cancer-related deaths in the United States (after lung cancer). According to the American Cancer Society, almost 150,000 new cases of colorectal cancer were diagnosed and approximately 50,000 people died from the disease last year.

  • Colon Cancer: Cancer that forms in the tissues of the colon (the longest part of the large intestine). Most colon cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).
  • Rectal Cancer: Cancer that forms in the tissues of the rectum (the last several inches of the large intestine closest to the anus).

Risk Factors

Labeled diagram showing the human colon, small intestine, rectum, stomach, anus, cecum, and appendix location.
Labeled diagram showing the human colon, small intestine, rectum, stomach, anus, cecum, and appendix location.

Risk factors for colorectal cancer include lifestyle, older age, and inherited genetic disorders that only occur in a small fraction of the population.

Other risk factors include diet, smoking, alcohol, lack of physical activity, family history of colon cancer and colon polyps, presence of colon polyps, race, exposure to radiation, and even other diseases such as diabetes, obesity.

A diet high in red, processed meat, while low in fiber increases the risk of colorectal cancer.

The risk of developing colorectal cancer also increases with age. Men and women aged 50 and older are at an increased risk for developing colorectal cancer, and should be screened at least every 5-10 years. Some people are at a higher risk and should be screened at an age younger than 50, including those with a personal or family history of inflammatory bowel disease, colorectal cancer or polyps.

An American Cancer Society study found that Women who smoked were more than 40% more likely to die from colorectal cancer than women who never had smoked. Male smokers had more than a 30% increase in risk of dying from the disease compared to men who never had smoked.

The comparison of colorectal cancer incidence in various countries strongly suggests that sedentarity, overeating (i.e., high caloric intake), and perhaps a diet high in meat (red or processed) could increase the risk of colorectal cancer. In contrast, a healthy body weight, physical fitness, and good nutrition decreases cancer risk in general. Accordingly, lifestyle changes could decrease the risk of colorectal cancer as much as 60-80%.

What are the Symptoms of Colorectal Cancer?

Colorectal cancer often has no symptoms until the disease has progressed beyond its earliest stages. The first symptoms of colon cancer are usually vague, like bleeding, weight loss, and fatigue (tiredness). Local (bowel) symptoms are rare until the tumor has grown to a large size. Generally, the nearer the tumor is to the anus, the more bowel symptoms there will be. Some potential signs and symptoms of colorectal cancer to watch for and ask your physician about include:

  • Cramping or stomach pain.
  • A feeling that you need to have a bowel movement that doesn't go away after doing so.
  • Rectal bleeding, dark stools, or blood in the stool.
  • Weakness and tiredness.
  • A change in bowel habits such as diarrhea, constipation, or narrowing of the stool that lasts for more than a few days.

Stages of Colon Cancer

After colon cancer has been diagnosed, tests are done to find out if cancer cells have spread within the colon or to other parts of the body. The following stages are used for colon cancer:

  • Stage 0 (Carcinoma in Situ)
  • Stage I
  • Stage II
  • Stage III
  • Stage IV

TNM System

Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe how deeply the primary tumour has grown into the bowel lining. Some stages are also divided into smaller groups that help describe the tumour in even more detail. TX: The primary tumour cannot be evaluated.

  • T0: There is no evidence of cancer in the colon or rectum.
  • Tis: Refers to carcinoma in situ (also called cancer in situ). Cancer cells are found only in the epithelium or lamina propria - top layers lining inside of the colon or rectum.
  • T1: The tumour has grown into the submucosa, which is the layer of tissue underneath the mucosa or lining of the colon.
  • T2: The tumour has grown into the muscularis propria - Deeper, thick layer of muscle that contracts to force along the contents of the intestines.
  • T3: The tumour has grown through the muscularis propria and into the subserosa or it has grown into tissues surrounding the colon or rectum.
  • T4a: The tumour has grown into the surface of the visceral peritoneum, which means it has grown through all layers of the colon.
  • T4b: The tumour has grown into or has attached to other organs or structures.

Node (N)

The 'N' in the TNM system stands for lymph nodes. The lymph nodes are tiny, bean-shaped organs located throughout the body. Lymph nodes help the body fight infections as part of the immune system. Lymph nodes near the colon and rectum are called regional lymph nodes. All others are distant lymph nodes that are found in other parts of the body. NX: The regional lymph nodes cannot be evaluated.

  • N0: There is no spread to regional lymph nodes.
  • N1a: There are tumour cells found in 1 regional lymph node.
  • N1b: There are tumour cells found in 2 to 3 regional lymph nodes.
  • N1c: There are nodules made up of tumour cells found in the structures near the colon that do not appear to be lymph nodes.
  • N2a: There are tumour cells found in 4 to 6 regional lymph nodes.
  • N2b: There are tumour cells found in 7 or more regional lymph nodes.

Metastasis (M)

The 'M' in the TNM system describes cancer that has spread to other parts of the body, such as the liver or lungs. This is called distant metastasis.

  • MX: Distant metastasis cannot be evaluated.
  • M0: The disease has not spread to a distant part of the body.
  • M1a: The cancer has spread to 1 other part of the body beyond the colon or rectum, but not to distant parts of the peritoneum (the lining of the abdominal cavity).
  • M1b: The cancer has spread to more than 1 part of the body other than the colon or rectum, but not to distant parts of the peritoneum.
  • M1c: The cancer has spread to distant parts of the peritoneum, and may or may not have spread to another part of the body beyond the colon or rectum.

Treatment

The treatment depends on the staging of the cancer. When colorectal cancer is caught at early stages (with little spread) it can be curable. However when it is detected at later stages (when distant metastases are present) it is less likely to be curable.

Most colorectal cancers begin as a polyp, which is a tissue growth that starts in the lining of the colon or rectum. Identifying and removing a polyp early in its development may prevent it from becoming cancerous. Surgery remains the primary treatment while chemotherapy and/or radiotherapy may be recommended depending on the individual patient's staging and other medical factors.

Some cancers, if caught very early, can be treated with a colonoscopy and without the need for surgery.

Newer more advanced minimally invasive techniques, such as laparoscopic or endoscopic resections, allow more patients to undergo curative surgery without the need for lengthy hospital stays or a stoma ("bag").

With these techniques, pain is considerably less and patients are able to return to work and their daily activities in significantly less time than with standard operations.

U.S. Colorectal Cancer Facts and Statistics

Of cancers that affect both men and women, colorectal cancer is the second leading cause of cancer-related deaths in the United States and the third most common cancer in men and in women. In 2011;

  • 51,783 people in the United States died from colorectal cancer, including 26,804 men and 24,979 women.*
  • 135,260 people in the United States were diagnosed with colorectal cancer, including 70,099 men and 65,161 women.*
  • Overall, the lifetime risk of developing colon cancer is about 1 in 20.
  • It is most often found in people 50 years or older, but can occur at any age.
  • It is one of the most detectable and treatable forms of cancer, and more than 90 percent of all cases can be prevented with recommended screening.
  • Everyone 50 years and older, and those with symptoms or a family history, should be screened regularly for colon cancer.

*Incidence counts cover about 99% of the U.S. population; death counts cover about 100% of the U.S. population.

Summary

Colorectal cancer often doesn't cause any symptoms at first, so it may remain unnoticed for a while.

Colorectal cancer is the 3rd most common form of cancer and 2nd leading cause of cancer related death in the Western world. Colon cancer typically affects older adults, though it can happen at any age. It usually begins as small, noncancerous (benign) clumps of cells called polyps that form on the inside of the colon. Over time some of these polyps can become colon cancers.

Signs and symptoms of colon cancer may include: Unexplained weight loss; rectal bleeding or blood in your stool; weakness or fatigue; a feeling that your bowel doesn't fully empty; persistent change in bowel movements including diarrhea or constipation and stool consistency; abdominal discomfort such as cramps, gas or pain.

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