What is colorectal cancer?

Colorectal cancer is a cancer that develops in the colon (colon cancer) or the rectum. It the latter case, it is also known as rectal cancer. Colorectal cancer is the third most common type of cancer, globally and can affect both men and women. There were 1.4 million new cases of colorectal cancer in 2012 worldwide with it being more common in developed countries.

This type of cancer affects the lower parts of the body’s digestive system. During digestion, food moves through the stomach, the small intestine, and the large intestine. The colon, a six foot long muscular tube, is part of the large intestine. It connects the small intestine to the rectum, and specializes in absorbing water and nutrients from food. It also stores waste matter, known as stool, which then moves from the colon into the rectum where it is evacuated from the body. The rectum is also part of the large intestine.

Most of the colorectal cancers that form are adenocarcinomas (cancers that begin in cells that produce and release mucus and other fluids). They begin as a growth called a “polyp”, which may form on the inner wall of the colon or the rectum. Some of these polyps can become cancerous over time, usually over the course of several years. The chances of these polyps turning into cancer depends on the kind of polyp. There are two main types of polyps:

  • Adenomatous polyps (adenomas): Those sometimes evolve into cancer, and are therefore considered a “pre-cancerous condition”.
  • Hyperplastic polyps and inflammatory polyps: These polyps are more common, but do not generally evolve into cancer.

Dysplasia, is another pre-cancerous condition in the lining of the colon or rectum in which the cells look abnormal but are not real cancer cells.

Early stages of colorectal cancer is usually diagnosed through a colonoscopy which consists of a procedure done under sedation where a camera is introduced into the colon to check for any abnormalities in or on the colorectal wall. During this procedure, a biopsy can be done to check for the presence of any cancerous cells. Screening for colorectall cancer is highly recommended to prevent cancer and decrease deaths. Doctors recommend colorectal screening starting from the age of 50 to 75.

Talk to your physician to discuss when it is right for you to get a screening.