Rectal Cancer Library
Learn about Rectal Cancer
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 takes in 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 colon (large bowel) is the first part of the large intestine and is about 5 feet long. Together, the rectum and anal canal make up the last part of the large intestine and are 6 to 8 inches long. The anal canal ends at the anus (the opening of the large intestine to the
outside of the body).
For more information about rectal cancer, see:
- Childhood Colorectal Cancer Treatment
- Colorectal Cancer Prevention
- Colorectal Cancer Screening
- Gastrointestinal Stromal Tumors Treatment (Adult)
- Genetics of Colorectal Cancer
Health history affects the risk of developing rectal cancer.
Anything that increases a person's chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop colorectal cancer, and it will develop in people who don't have any known risk factors. Talk to your doctor if you think you may be at risk for colorectal cancer.
Risk factors for colorectal cancer include the following:
- Having a family history of colon or rectal cancer in a first-degree relative (parent, sibling, or child).
- Having a personal history of cancer of the colon, rectum, or ovary.
- Having a personal history of high-risk adenomas (colorectal polyps that are 1 centimeter or larger in size or that have cells that look abnormal under a microscope).
- Having inherited changes in certain genes that increase the risk of familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary nonpolyposis colorectal cancer).
- Having a personal history of chronic ulcerative colitis or Crohn disease for 8 years or more.
- Having three or more alcoholic drinks per day.
- Smoking cigarettes.
- Being Black.
- Obesity.
Older age is a main risk factor for most cancers. The chance of getting cancer increases as you get older.
Signs of rectal cancer include a change in bowel habits or blood in the stool.
These and other signs and symptoms may be caused by rectal cancer or by other conditions. Check with your doctor if you have any of the following:
- Blood (either bright red or very dark) in the stool.
- A change in bowel habits.
- Diarrhea.
- Constipation.
- Feeling that the bowel does not empty completely.
- Stools that are narrower or have a different shape than usual.
- General abdominal discomfort (frequent gas pains, bloating, fullness, or cramps).
- Change in appetite.
- Weight loss for no known reason.
- Feeling very tired.
Tests that examine the rectum and colon are used to diagnose rectal cancer.
The following tests and procedures may be used:
- Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Digital rectal exam (DRE): 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. In women, the vagina may also be examined.
- Colonoscopy: A procedure to look inside the rectum and colon for polyps (small pieces of bulging tissue), abnormal areas, or cancer. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.
- Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer. Tumor tissue that is removed during the biopsy may be checked to see if the patient is likely to have the gene mutation that causes HNPCC. This may help to plan treatment.
- Immunohistochemistry: A laboratory test that uses antibodies to check for certain antigens (markers) in a sample of a patient’s tissue. The antibodies are usually linked to an enzyme or a fluorescent dye. After the antibodies bind to a specific antigen in the tissue sample, the enzyme or dye is activated, and the antigen can then be seen under a microscope. This type of test is used to help diagnose cancer and to help tell one type of cancer from another type of cancer.
- Carcinoembryonic antigen (CEA) assay: A test that measures the level of CEA in the blood. CEA is released into the bloodstream from both cancer cells and normal cells. When found in higher than normal amounts, it can be a sign of rectal cancer or other conditions.
- Microsatellite instability (MSI): A laboratory test in which tumor tissue is checked for cells that may have a defect in genes involved in DNA repair. The findings may indicate whether or not the patient has a type of cancer linked to an inherited cancer syndrome such as HNPCC (also known as Lynch syndrome).
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis 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 lymph nodes, nearby organs, or other places in the body).
- Whether the cancer is related to a defect in genes involved in DNA repair.
- Whether the tumor has spread into or through the bowel wall.
- Where the cancer is found in the rectum.
- Whether the bowel is blocked or has a hole in it.
- Whether all of the tumor can be removed by surgery.
- The patient’s general health.
- Whether the cancer has just been diagnosed or has recurred (come back).
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