While no one knows the exact causes of colorectal cancer, there are several known risk factors, including age and family history.
More than 90 percent of people with colorectal cancer are diagnosed after age 50. The average age at diagnosis is 72.
Close relatives of a person with a history of colorectal cancer are somewhat more likely to develop the disease, especially if the relative had the cancer at a young age.
Personal history of cancer
A person who has already had colorectal cancer may develop colorectal cancer a second time. Women with a history of cancer of the ovary, uterus or breast are also at a somewhat higher risk.
Ulcerative colitis or Crohn's disease
A person who has a condition that causes inflammation of the colon for many years is at increased risk.
Polyps are growths on the inner wall of the colon or rectum, common in people over age 50. Most polyps are benign, but some can become cancerous. Finding and removing polyps may reduce the risk of colorectal cancer. Learn more about colorectal polyps.
Studies suggest diets high in fat and low in calcium, folate and fiber may increase the risk of colorectal cancer.
Obesity and lack of exercise is linked to an increase risk of colorectal cancer.
Frequent smokers may be at increase risk of developing polyps and colorectal cancer.
If you have a family history of colorectal cancer or other risk factors, talk to your doctor about reducing your risk and planning an appropriate schedule for checkups.
Download a Colonoscopy Screening Card
There are usually no symptoms of polyps in early colon and rectal cancers. If you are experiencing any of the following symptoms, please discuss it with your doctor.
Changes in your bowel habits, such as bowel movements that are either more or less frequent than normal
Constipation (difficulty having a bowel movement or straining to have a bowel movement)
Diarrhea (loose or watery stools)
Intermittent (alternating) constipation and diarrhea
Bright red or dark red blood in your stools or black, dark colored, "tarry" stools
Stools that are thinner than normal ("pencil stools") or feeling as if you cannot empty your bowels completely
Abdominal (midsection) discomfort, bloating, frequent gas pains, or cramps
Most often, these symptoms are not due to cancer and could be caused by other common colorectal disorders. Anyone with these symptoms should see a doctor to be diagnosed and treated as early as possible. Usually, early cancer does not cause pain. It is important not to wait to feel pain before seeing a doctor.