March is designated as National Colorectal Cancer Awareness Month by the American Cancer Society. Colorectal cancer is a cancer that starts in the colon or the rectum. These cancers can also be named 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.
Most colorectal cancers begin as a growth called a polyp on the inner lining of the colon or rectum Some types of polyps can change into cancer over the course of several years, but not all polyps become cancer. The chance of changing into a cancer depends on the kind of polyp. The 2 main types of polyps are:
Adenomatous polyps (adenomas): These polyps sometimes change into cancer. Because of this, adenomas are called a pre-cancerous condition.
Hyperplastic polyps and inflammatory polyps: These polyps are more common, but in general they are not pre-cancerous.
Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women in the United States. Overall, the lifetime risk of developing colorectal cancer is: about 1 in 21 (4.7%) for men and 1 in 23 (4.4%) for women. This risk is slightly lower in women than in men. The American Cancer Society’s estimates for the number of colorectal cancer cases in the United States for 2017 are:
- 95,520 new cases of colon cancer
- 39,910 new cases of rectal cancer
For more information about colorectal cancer, visit the American Cancer Society.