Colorectal Cancer Signs and Symptoms
Colorectal cancer might not cause symptoms right away, but if it does, it may cause one or more of these symptoms:
- A change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days
- A feeling that you need to have a bowel movement that is not relieved by having one
- Rectal bleeding with bright red blood
- Blood in the stool, which may make the stool look dark
- Cramping or abdominal (belly) pain
- Weakness and fatigue
- Unintended weight loss
Colorectal cancers can often bleed into the digestive tract. Sometimes the blood can be seen in the stool or make it look darker, but often the stool looks normal. But over time, the blood loss can build up and can lead to low red blood cell counts (anemia). Sometimes the first sign of colorectal cancer is a blood test showing a low red blood cell count.
Many of these symptoms can be caused by conditions other than colorectal cancer, such as infection, hemorrhoids, or irritable bowel syndrome. Still, if you have any of these problems, it’s important to see your doctor right away so the cause can be found and treated, if needed.
American Cancer Society. Colorectal Cancer Facts & Figures 2014-2016. Atlanta, Ga: American Cancer Society; 2014.
Libutti SK, Salz LB, Willett CG, Levine RA. Chapter 57: Cancer of the colon. In: DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 10th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2015.
Libutti SK, Willett CG, Salz LB, Levine RA. Chapter 60: Cancer of the rectum. In: DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 10th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2015.
Sigurdson ER, Benson AB, Minsky B. Cancer of the rectum. In: Niederhuber JE, Armitage JO, Dorshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 5th ed. Philadelphia, Pa. Elsevier: 2014: 1336-1359.
Steele SR, Johnson EK, Champagne B et al. Endoscopy and polyps-diagnostic and therapeutic advances in management. World J Gastroenterol 2013; 19(27): 4277-4288.
Van Schaeybroeck S, Lawler M, Johnston B, et al. Colorectal cancer. In: Neiderhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 5th ed. Philadelphia, Pa: Elsevier; 2014: 1278-1335.
Last Medical Review: October 15, 2016 Last Revised: March 2, 2017
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