Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School



Polyps and early colorectal cancer generally don't cause symptoms. As a result, they are usually caught during screening.

More advanced cancer can cause:

  • More or less frequent bowel movements than usual

  • Diarrhea or constipation

  • Blood in the stool (bright red, black or very dark)

  • Narrowed stools (about the thickness of a pencil)

  • Bloating, fullness or stomach cramps

  • Frequent gas pains

  • A feeling that the bowel does not empty completely

  • Weight loss without dieting

  • Continuing fatigue

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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