Colon and rectal cancers
Description
An in-depth report on the causes, diagnosis, treatment, and prevention of colorectal cancer.
Alternative Names
Colorectal cancer
Symptoms
It is possible to have colon or rectal cancer without symptoms. Many patients are free of symptoms until their tumors are quite advanced.
Weight Loss and Changes in Bowel Movements
Weight loss and changes in bowel movements are general symptoms for colon cancer, but also occur in many other diseases.
Rectal Bleeding
Blood in the stools is a common sign of many intestinal cancers. It may appear red if it is fresh or black if it is old. It should be reported to a doctor immediately, even though it is often caused by conditions other than cancer, including:
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Hemorrhoids
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Minor tears around the rectal or anal areas
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Diverticulosis
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Stools can turn red after eating certain red foods, such as beets or red licorice
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Iron supplements and medications that have bismuth subsalicylate, most commonly Pepto-Bismol, can cause stools to turn black
Nevertheless, blood in the stools is an abnormal finding that should never be ignored. Always report it to your doctor for further advice.
Symptoms of Cancers in Specific Areas of the Colon
Symptoms of colorectal cancer vary widely depending on the location of the cancer within the large intestine.
Tumors in the Cecum and Ascending Colon (Right Colon).
The waste matter in the first portion of the colon is in liquid or semi-liquid form. Tumors that develop here do not change bowel habits or stool formation, but they may cause intermittent or chronic bleeding. Although the stools look normal, patients may develop symptoms of anemia from iron deficiency. Such symptoms include weakness, fatigue, heart palpitations, shortness of breath, and exercise intolerance.
Tumors in the Transverse Colon.
As waste material passes across the upper quadrants of the abdomen (the transverse colon), the intestine absorbs water, and the waste matter becomes more solid. In addition to bleeding, tumors here may cause cramps, gas, partial or complete obstruction, and even perforation of the bowel. Anemia can also occur.
Tumors in the Descending Colon and Rectum (Left Colon).
When tumors partially block the lower intestine, thin, pencil-shaped stools may form. Bowel habits can change. Tumors in the rectum and lowest part of the intestine can cause pain and a feeling of fullness. Defecation may be painful or patients may feel the urge to defecate, but nothing happens. Bleeding from these locations may be brisk and bright red or maroon, but cancer is often detected before symptoms of chronic anemia develop.
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Review Date: 3/6/2007
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Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital (9/1/2006).
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