The colon and rectum are part of the large intestine. Colorectal cancer occurs when tumors form in the lining of the large intestine. It is common in both men and women. The risk of developing colorectal cancer rises after age 50. You're also more likely to get it if you have colorectal polyps, a family history of colorectal cancer, ulcerative colitis or Crohn's disease, eat a diet high in fat, or smoke.

Symptoms of colorectal cancer include

• Diarrhea or constipation
• A feeling that your bowel does not empty completely
• Blood (either bright red or very dark) in your stool
• Stools that are narrower than usual
• Frequent gas pains or cramps, or feeling full or bloated
• Weight loss with no known reason
• Fatigue
• Nausea or vomiting

Because you may not have symptoms at first, it's important to have screening tests. Everyone over 50 should get screened. Tests include colonoscopy and tests for blood in the stool. Treatments for colorectal cancer include surgery, chemotherapy, radiation, or a combination. Surgery can usually cure it when it is found early.

NIH: National Cancer Institute