Colorectal cancer is when abnormal cells grow together in the colon or rectum to form polyps, and those polyps can turn into cancer. It’s called colon or rectal cancer depending on where the polyp is located.
Colorectal cancer is the third most common cancer in the U.S.—the second leading cause of cancer-related deaths among men and the third leading cause for women. It occurs mostly in people older than 50.
An estimated 60 percent of colorectal cancer deaths could be prevented if people were screened routinely.
We don’t know what causes a polyp to become cancerous. Colon polyps are common, but need to be found early to avoid turning into cancer.
Symptoms are usually not evident until the cancer starts to spread.
- Blood in stool or very dark stools
- Stools that are narrower than usual
- Change in bowel habits—more frequent or feeling that the bowels are not emptying completely
- Frequent gas pains or cramps
- Diarrhea or constipation
Diagnosis and screenings
The American Cancer Society recommends regular screenings for everyone age 50 and older. The doctor will do a visual test and/or stool-based test.
- Visual exams include:
- A colonoscopy every 10 years. This screening test involves using a thin, flexible tube with a camera on the end to allow the doctor to see the inside of the colon and rectum. A colonoscopy involves removing polyps and taking tissue samples of abnormal polyps.
- A flexible sigmoidoscopy every 5 years. This test is similar to a colonoscopy, but only covers the lower part of the colon.
- Stool-based tests include:
- A highly sensitive fecal immunochemical test (FIT) every year
- A highly sensitive guaiac-based fecal occult blood test (gFOBT) every year
- A multi-targeted stool DNA test (MT-sDNA) every 3 years
When colorectal cancer is caught early, the survival rate is 90 percent. It’s usually treated with surgery, chemotherapy, or radiation.