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Cancer Treatment Centers of America

Colorectal cancer symptoms

Colorectal cancer symptoms may be minimal or non-existent during the early stages of the disease. The signs and symptoms of colorectal cancer may not arise until the disease has progressed into stage II or beyond. Regular screening tests for colon and rectal cancer, especially with a colonoscopy, is recommended as part of a health plan for anyone over 50 years old or anyone under 50 who are at high risk or have a family history of the disease or other cancers. Talk with your doctor about when you should start regular colorectal cancer screening.

Several tests may be used to diagnose colorectal cancer. These tests may include a colonoscopy, or other endoscopic procedures, stool tests, or other lab tests, or an MRI, CT scan or PET/CT scan. In many cases, a biopsy may be required. These imaging and laboratory tests may also be used to track the size of tumors and monitor response to treatment.

Learn more about diagnostic evaluations for colorectal cancer.

colorectal cancer symptoms

Rectal cancer symptoms

The rectum is the last several inches of the large intestine that attaches the colon to the anus. While colon cancer is more common, tumors can develop in the rectum as well. The symptoms of rectal cancer may be similar to those of other bowel diseases, such as ulcerative colitis or Crohn's disease. But while symptoms of inflammatory bowel disease may subside during periods of remission, rectal cancer symptoms may be more severe and persistent as the cancer develops. Rectal cancer or pre-cancerous growths in the rectum may be found and treated early during regular screenings.

Rectal cancer signs

Tumors in the rectum may change the consistency, shape or the frequency of bowel movements. Symptoms may increase and become more severe as the cancer spreads throughout the rectum or possibly into the colon. Bleeding from the rectum or blood from the tumor may change the color of stools, from a bright red to very dark or tar-like.

Rectal cancer signs related to bowel habits may include:

  • Diarrhea
  • Constipation
  • An inability to completely empty the bowel
  • Bloody stool
  • Change in the size or shape of stools

Local and systemic rectal cancer symptoms

Rectal cancer may show no symptoms in its early stages. However, more systemic changes may result as the tumor grows deeper into the lining the rectum or if the cancer spreads (metastasizes) throughout the body.

Symptoms of rectal cancer may include:

  • Pain in the rectum
  • Abdominal pain or discomfort
  • Frequent gas pains or stomach cramps
  • A bloated or full feeling
  • Change in appetite
  • Unexplained weight loss
  • Fatigue
  • Weakness

If you have any of these symptoms, it is important to consult your doctor or health care provider.


Last Revised: 06/18/2018

Understanding cancer symptoms

These symptoms may be attributed to a number of conditions other than cancer. If you notice any cancer signs or symptoms, it's important to visit your doctor for an accurate diagnosis.

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