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Diagnosing Colorectal Cancer

Signs and Symptoms

Often there are no obvious signs of colorectal cancer, but some symptoms can include:

  • Change in bowel frequency, such as alternating episodes of diarrhea and constipation.
  • Bloody bowel movements or rectal bleeding.
  • General abdominal discomfort.
  • Unexplained weight loss.
  • Chronic fatigue.
  • Bloating.
  • Unexplained anemia.

Screening for Colorectal Cancer

The American Cancer Society recommends that, beginning at age 50, both men and women be screened for colorectal cancer according to one of the following schedules:

  • A yearly fecal occult blood test where your stool will be checked for blood.
  • A double-contrast barium enema every five years. During this test, your colon is filled with a fluid containing barium. The barium is then drained out and air is put into the intestine. X-rays of the area are then taken to look for abnormalities.
  • Every 10 years, a colonoscopy where the doctor uses a long, lighted tube to look inside the rectum and the entire colon for polyps or other abnormal areas that may be cancerous.

People who have any of the colorectal cancer risk factors should consult with their doctor about earlier, more frequent screening.

Click here to learn more about Colorectal Cancer Screenings.


Diagnosis Methods

Special tests to evaluate the colon and rectum are used to detect and diagnose colorectal cancer.

  • A physical exam to assess your overall health, including a digital rectal exam (DRE) to evaluate the rectum for abnormal masses.
  • Fecal occult blood test.
  • A sigmoidoscopy to look inside the rectum and sigmoid colon for polyps or other abnormal areas that may be cancerous using a thin, lighted tube.
  • A double-contrast barium enema.
  • A colonoscopy.
  • To determine for sure if you have cancer, some tissue will be removed during sigmoidoscopy or colonoscopy and examined under a microscope. This test is called a biopsy. Your doctor may also request a CT or PET scan to see if other body parts are involved.