Rectal Cancer is a disease in which malignant (cancer) cells form in the tissues of the rectum.

The rectum is part of the body's digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The first 6 feet of the large intestine are called the large bowel or colon. The last 6 inches are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).

Anatomy of the lower digestive system, showing the colon and other organs.

Age and family history can affect the risk of developing Rectal Cancer.

The following are possible risk factors for Rectal Cancer:

• Age 50 or older.
• A family history of cancer of the colon or rectum.
• A personal history of cancer of the colon, rectum, ovary, endometrium, or breast.
• A personal history of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn disease.
• Certain hereditary conditions, such as familial adenomatous polyposis and hereditary nonpolyposis Colon Cancer (HNPCC; Lynch syndrome).

Possible signs of Rectal Cancer include a change in bowel habits or blood in the stool.

These and other symptoms may be caused by Rectal Cancer. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

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

Tests that examine the rectum and colon are used to detect (find) and diagnose Rectal Cancer.

Tests used in diagnosing Rectal Cancer include the following:

• Fecal occult blood test: A test to check stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing.
  
  Fecal Occult Blood Test (FOBT) kit to check for blood in stool.
• Digital rectal exam: An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual.
• Barium enema: A series of x-rays of the lower gastrointestinal tract. A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the lower gastrointestinal tract and x-rays are taken. This procedure is also called a lower GI series.
  
  Barium enema procedure. The patient lies on an x-ray table. Barium liquid is put into the rectum and flows through the colon. X-rays are taken to look for abnormal areas.
• Sigmoidoscopy: A procedure to look inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer. A sigmoidoscope (a thin, lighted tube) is inserted through the rectum into the sigmoid colon. Polyps or tissue samples may be taken for biopsy.
  
  Sigmoidoscopy. A thin, lighted tube is inserted through the anus and rectum and into the lower part of the colon to look for abnormal areas.
• Colonoscopy: A procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope (a thin, lighted tube) is inserted through the rectum into the colon. Polyps or tissue samples may be taken for biopsy.
  
  Colonoscopy. A thin, lighted tube is inserted through the anus and rectum and into the colon to look for abnormal areas.
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

• The stage of the cancer (whether it affects the inner lining of the rectum only, involves the whole rectum, or has spread to other places in the body).
• The patient's general health.
• Whether the cancer has just been diagnosed or has recurred (come back).