Colon Cancer Symptoms

Colorectal cancers are cancers of the colon or rectum, the last several inches of the colon. Most colorectal cancers begin as small, non-cancerous clumps of cells called polyps, which may become cancers over time. Many cases of colon cancer have no symptoms until the cancer has advanced, but learning to recognize possible colon cancer symptoms can help with early detection and treatment.

Colorectal cancer may cause one of more of the following symptoms:

• A change in bowel habits, such as diarrhea, constipation or narrowing of the stool, that lasts for more than a few days

• A sense of urgency or bowel fullness that isn’t relieved by a bowel movement

• Rectal bleeding

• Blood in the stool, or dark stool

• Persistent abdominal discomfort, such as cramps, gas or pain

• Unexplained weight loss

• Weakness or fatigue

Colorectal cancers may bleed into the digestive tract, and bleeding may be occurring even if the stool looks normal. Over time, this blood loss can lead to low red blood cell counts, or anemia. In some cases, a blood test showing anemia is the first sign of colorectal cancer.

When to See a Doctor

If you notice any symptoms associated with colon cancer, such as a persistent change in bowel habits or blood in your stool, make an appointment with your doctor. Routine colorectal cancer screening is the best way to prevent colon cancer or find it at any early, more treatable stage, when you might not have any colon cancer symptoms. Your doctor can advise you about when you should begin screening for colorectal cancer. Guidelines generally recommend that colorectal cancer screenings begin at age 45, but your doctor may recommend earlier or more frequent screening if you have other risk factors, such as a family history of colorectal cancer.