Rectal Cancer

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Rectal cancer is cancer in the rectum, the last part of the large intestine. The rectum allows waste to pass through the anal canal and out of the body.


Cancer occurs when cells in the body divide without control or order. Eventually, these uncontrolled cells form a growth or tumor. The term cancer refers to malignant growths. These growths invade nearby tissues and spread to other parts of the body. It is not clear exactly what causes these problems in the cells, but is probably a combination of genetics and the environment.

Risk Factors

Being over 50 years of age increases your chance of rectal cancer. Other factors that may increase your chance of rectal cancer include:

  • Genetics
  • History of colon or rectal cancer, or polyps
  • Family history of colon or rectal cancer, especially a parent, sibling, or child
  • Radiation therapy for prostate cancer
  • Obesity
  • Smoking
  • Diet high in fat and low in fiber
  • Heavy alcohol intake
  • Physical inactivity


In most cases, there are no symptoms with rectal cancer. When symptoms do appear, they may include:

  • A change in bowel habits
  • Blood, either bright red, or black and tarry, in the stool
  • Stools that are narrower than usual
  • Diarrhea, constipation, or feeling that the bowel does not empty completely
  • General abdominal discomfort, such as frequent gas pains, bloating, fullness, and/or cramps
  • Unexplained weight loss
  • Constant feeling of fatigue or tiredness


Your rectum will be checked for lumps or abnormal areas. Your stool may be tested. This can be done with:

  • Blood tests
  • Fecal occult blood test
  • Biopsy

Your bodily structures may need to be viewed using an instrument. This can be done with:

Images may be taken of your bodily structures. This can be done with:

  • Barium enema
  • CT colonography
  • CT scan
  • Positron emission tomography (PET) scan
  • Transrectal ultrasound


Treatment may include one or more of the following options:

  • Surgery
    • Polypectomy and local excision 
    • Local transanal resection 
    • Transanal endoscopic microsurgery (TEM) 
    • Low anterior resection
    • Proctectomy 
    • Abdominoperineal resection 
    • Pelvic exenteration 
  • Radiation Therapy
  • Chemotherapy
  • Targeted Therapy


The causes of most cancers are not known. However, it is possible to prevent many colon and rectal cancers by finding and removing polyps that could become cancerous. Beginning at age 50, both men and women at average risk should follow one of the following screening options:

  • Colonoscopy every 10 years
  • Flexible sigmoidoscopy every 5 years
  • CT colonography every 5 years
  • Double-contrast barium enema every 5 years
  • Stool DNA test every 3 years
  • Annual fecal occult blood test (FOBT)
  • Annual fecal immunochemical test (FIT)

People with any of the following risk factors should begin colon and rectal cancer screening earlier and/or undergo screening more often:

  • African Americans or Native Americans
  • Strong family history of colon or rectal cancer, or polyps
  • Family history of hereditary colon or rectal cancer syndromes
  • History of colon or rectal cancer, or adenomatous polyps
  • History of chronic inflammatory bowel disease

There are also lifestyle changes that may reduce your risk of rectal cancer. These include:

  • Not smoking
  • Drinking alcohol in moderation — no more than 2 drinks a day if you are a man, and no more than 1 drink a day if you are a woman
  • Eating a healthy diet high in fruits, vegetables, and whole grains, and low in red meat
  • Being physically active by exercising at least 30 minutes a day on most days of the week
  • Maintaining a healthy weight


Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.