Colorectal cancer

Cancer of the rectum or colon
Cancer care
cancer diagnosis

Colon cancer and rectal cancer are often grouped together because they have many features in common.

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How common is colon cancer?

Colon cancer is one of the most common cancers if we exclude skin cancer. It becomes more common amongst older individuals though.

1 in 77
1 in 77
1 in 77
males have a lifetime risk of developing colorectal cancer.
1 in 132
1 in 132
1 in 132
females have a lifetime risk of developing colorectal cancer.
 
 
 

Other types of cancer

Below you can find information on other types of cancer screenings that you might be interested in.

Bladder cancer

Cancer of the bladder

The fourth most common cancer in men and the twelfth most common cancer in women.

Breast cancer

Cancer of the breast

Cancer that forms in the cells of the breasts and can occur in both men and women, but it's far more common in women.

Cervical cancer

Cancer of the cervix

If detected early, cancer of the cervix can be one of the most successfully treatable cancers...

Colorectal cancer

Cancer of the rectum or colon

Colon cancer and rectal cancer are often grouped together because they have many features in common.

Sarcoma

Cancerous tumours of the soft tissues

A broad term for cancers that start in soft tissues like muscle, tendons, fat, lymph and blood vessels, and nerves.

Throat cancer

Cancer of the throat

A fast-growing cancer; therefore early treatment is key to having a good quality of life.

Lung Cancer

Caner of the lung

People who smoke are at a greater risk of getting lung cancer, though lung cancer can also occur in people who have never smoked.

Melanoma

A type of skin cancer

The primary known cause of melanoma, as well as all other types of skin cancer, is exposure to ultraviolet radiation contained in sunlight.

Lymphoma

Cancer of lymphocytes

Lymphoma can be divided broadly into 2 types of lymphoma: Hodgkins Lymphoma or Hodgkins Disease (HD) and Non-Hodgkins Lymphoma (NHL).

Head and neck cancers

Cancer of the head and neck

These cancers, that could include oesophageal cancer, usually begin in the cells that line the moist surfaces (mucosal membranes) inside the...

Ovarian cancer

Cancer of the ovary

Recent evidence suggests that many ovarian cancers may actually start in the cells in the far end of the fallopian...

Prostate cancer

Cancer of the prostate gland

Prostate cancer is one of the most common types of cancer in men. The lifetime risk for prostate cancer in men in South Africa, is 1 in 18.

Stomach cancer

Also known as gastric cancer

Most cancers of the stomach are adenocarcinomas. These cancers develop from the gland cells in the innermost lining of the stomach.

Thyroid cancer

Cancer of the thyroid gland

The thyroid gland makes hormones that help regulate your metabolism, heart rate, blood pressure, and body temperature.

Uterine cancer

Cancer of the uterus or womb

Most uterine cancer begins in the layer of cells that form the lining (endometrium) of the uterus.

 
 
 

Colorectal Cancer

Colorectal cancer starts in the colon or the rectum. These cancers can also be called colon cancer or rectal cancer, depending on where they start. Colon cancer and rectal cancer are often grouped together because they have many features in common.

Overall, the lifetime risk of developing colorectal cancer is about 1 in 23 (4.3%) for men and 1 in 25 (4.0%) for women. The rate of people being diagnosed with colon or rectal cancer each year has dropped overall since the mid-1980s, mainly because more people are getting screened and changing their lifestyle-related risk factors.

What is colorectal cancer?

Most colorectal cancers start as a growth on the inner lining of the colon or rectum. These growths are called polyps.

Some types of polyps can change into cancer over time (usually many years), but not all polyps become cancer. If cancer forms in a polyp, it can grow into the wall of the colon or rectum over time. The wall of the colon and rectum is made up of many layers. Colorectal cancer starts in the innermost layer (the mucosa) and can grow outward through some or all of the other layers.

When cancer cells are in the wall, they can then grow into blood vessels or lymph vessels (tiny channels that carry away waste and fluid). From there, they can travel to nearby lymph nodes or to distant parts of the body.

Most colorectal cancers start as a growth on the inner lining of the colon or rectum.

Symptoms

Signs and symptoms of colon cancer may include:

  • A change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days
  • Rectal bleeding with bright red blood
  • Cramping or abdominal (belly) pain
  • Unintended weight loss
  • A feeling that you need to have a bowel movement that's not relieved by having one
  • Blood in the stool, which might make the stool look dark brown or black
  • Weakness and fatigue

Causes

The exact cause of colorectal cancer is unknown, but cancers are often caused by changes in the DNA inside our cells. DNA is the chemical in our cells that makes up our genes, which control how our cells function. When cells start to grow abnormally and out of control, they are referred to as cancerous.

In most cases of colorectal cancer, the DNA mutations that lead to cancer are acquired during a person’s life rather than having been inherited.

Risk factors

A risk factor is anything that raises your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t.

Many lifestyle-related factors have been linked to colorectal cancer. In fact, the links between diet, weight, and exercise and colorectal cancer risk are some of the strongest for any type of cancer.

  • Having a family history of colon or rectal cancer in a first-degree relative (parent, sibling, or child).
  • Having a personal history of cancer of the colon, rectum, or ovary.
  • Having a personal history of high-risk adenomas (colorectal polyps that are 1 centimeter or larger in size or that have cells that look abnormal under a microscope).
  • Older age is a main risk factor for most cancers.
  • Having inherited changes in certain genes that increase the risk of familial adenomatous polyposis (FAP) or Lynch syndrome.
  • Older age is a main risk factor for most cancers.
  • Having inherited changes in certain genes that increase the risk of familial adenomatous polyposis (FAP) or Lynch syndrome.
  • If you have inflammatory bowel disease (IBD), including either ulcerative colitis or Crohn’s disease, your risk of colorectal cancer is increased.
  • Colorectal cancer has been linked to moderate to heavy alcohol use, for example having three or more alcoholic drinks per day.
  • People who have smoked tobacco for a long time are more likely than people who don't smoke to develop and die from colorectal cancer.
  • If you are overweight or obese (very overweight), your risk of developing and dying from colorectal cancer is higher. Being overweight raises the risk of colon and rectal cancer in both men and women, but the link seems to be stronger in men.
  • A diet that's high in red meats (such as beef, pork, lamb, or liver) and processed meats (like hot dogs and some luncheon meats) raises your colorectal cancer risk.
  • If you're not physically active, you have a greater chance of developing colon cancer. Regular moderate to vigorous physical activity can help lower your risk.

Cancers can be caused by DNA mutations (gene defects) that turn on oncogenes or turn off tumor suppressor genes.

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