Rectal Cancer

Rectal cancer occurs when cancerous cells develop in the tissue of the rectum. The rectum is the last part of the large intestine and leads to the anus, which is the opening to the outside of the body. Body waste is stored in the rectum until it is eliminated from the body through the anus.

Although rectal cancer is a life-threatening disease, it is a highly curable form of cancer if found early. Therefore, regular check-ups and screenings are very important.

Although the exact cause of rectal cancer is unknown, certain risk factors have been identified that may increase a person's chance of developing the disease. These include:

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  • Age — The majority of rectal cancers are diagnosed in people aged 50 or older, although the disease affects all ages.
  • Bowel disease — A history of colorectal cancer, intestinal polyps, and diseases such as chronic ulcerative colitis, Crohn's disease and inflammatory bowel disease increase a person's chance of developing rectal cancer.
  • Diet and exercise — A diet high in fat, particularly from animal sources, and an inactive, sedentary lifestyle can increase a person's chance of developing rectal cancer.
  • Ethnic background and race — Jews of Eastern European descent, called Ashkenazi Jews, have a higher rate of rectal cancer. African-Americans and Hispanics have a higher death rate caused by rectal cancer, which may be caused by insufficient screenings, poor diet and lack of exercise.
  • Family history/genetic factors — Specific genes have been identified that significantly increase a person's chance of having rectal cancer. People with a strong family history of colorectal cancer, as defined by cancer or polyps in a first-degree relative younger than 60 or two first-degree relatives of any age, are also at increased risk for developing rectal cancer.
  • Smoking and alcohol — Research suggests that smokers and heavy drinkers have an increased chance of developing rectal cancer.
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Common signs and symptoms of rectal cancer include:

  • A change in bowel habits
  • Diarrhea, constipation, or feeling that the bowel does not empty completely
  • Blood, either bright red or very dark in the stool
  • Stools that are narrower than usual
  • General abdominal discomfort such as frequent gas pains, bloating, fullness or cramps
  • Weight loss with no known reason
  • Constant tiredness
  • Vomiting

In making a diagnosis of rectal cancer, your doctor will first start by recording your medical history, asking about any symptoms you may be experiencing and conducting a thorough physical examination. He or she also may recommend one or more of the following diagnostic tests:

  • Digital Rectal Exam — This exam involves the doctor or nurse inserting a gloved, lubricated finger into the rectum to feel for an abnormalities.
  • Barium Enema — Also known as a lower gastrointestinal series, this test involves taking X-rays of the large intestines.
  • Fecal Occult Blood Test — This is a noninvasive test that detects the presence of hidden, or occult blood in the stool. Such blood may arise from anywhere along the digestive tract. Hidden blood in the stool is often the first, and in many cases the only, warning sign that a person has colorectal cancer.
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Treatment for rectal cancer may include surgery, radiation therapy or chemotherapy, or a combination of these approaches.


Surgery is the main treatment for all stages of rectal cancer, although radiation, chemotherapy, or both are often recommended in combination.

Some patients who undergo surgery for rectal cancer require a permanent colostomy — a surgically created opening in the abdominal wall through which waste is excreted. If you have a colostomy, our specially trained nurses will help you learn how to manage the colostomy and incorporate it into your lifestyle.

Depending on the location, stage and size of your tumor, your doctor will remove your cancer with one of the following methods:

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Reviewed by health care specialists at UCSF Medical Center.