Colon cancer forms in the tissues of the largest part of the large intestine (the colon). Cancers of the colon usually occur in cells that make mucus and are called adenocarcinomas. Rectal cancer forms in the last several inches of the large intestine called the rectum and close to the anus, the sphincter that controls bowel movements. The most common symptoms of colon and rectal cancer involve changes in bowel habits.
Constipation
Constipation is defined as having fewer than three bowel movements in a week. The stool (feces) is dry, hard and difficult or painful to pass. If constipation occurs for longer than a week and is not relieved by over-the-counter medicines, increased fiber in the diet and increased fluid intake, contact your doctor.
Diarrhea
Loose, wet stools that occur more than 3 times a day for more than 3 days is not considered normal and may be a symptom of colon or rectal cancer. Diarrhea may be accompanied by dehydration, pain in the abdomen and rectum, or blood in the stool.
Alternating Constipation and Diarrhea
Any change in bowel habits is important to watch. Alternating constipation and diarrhea may be a sign of cancer in the colon or rectum.
Blood in the Stool
Bright red blood or dark red blood may occur in the stool when cancer is present. Routinely look at the stool in the toilet to see if blood is present. Blood in the stool may occur even when bowel habits are regular.
Change in Size of Stool
Ribbon-like or pencil size stools may indicate colon and rectal cancer. When a growth (tumor or cancerous polyp) mechanically blocks the intestine, the stool may be reshaped to move around the blockage.
Abdominal Discomfort
Bloating in the abdomen causes it to feel full and tight. Cramping or excess gas (flatulence) may also cause abdominal discomfort.
Digestive Tract Symptoms
Weight loss, nausea and vomiting may also be symptoms of colon and rectal cancer. These symptoms are more advanced than local symptoms related to changes in bowel habits.
No Symptoms
Some colon and rectal cancers do not have symptoms, so routine screening is important. Talk to your doctor about when screening should begin. Screening includes colonoscopy, fecal occult (hidden) blood tests on the stool, and other tests to determine if signs of colon and rectal cancer are present in the intestine. A family history of colon or rectal cancer should be discussed with your physician.
