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General Information About Rectal Cancer
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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). | Enlarge | | | | Anatomy of the lower digestive system, showing the colon and other organs. |
See the following PDQ summaries for more information about rectal cancer:
Age and family history can affect the risk of developing rectal
cancer.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. The following are possible risk
factors for rectal cancer:
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.
- Diarrhea.
- Constipation.
- Feeling that the bowel does not
empty completely.
- Stools that are narrower or have a different shape than usual.
- Blood (either bright red or very dark) in the stool.
- 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 detect (find) and
diagnose rectal cancer.
Tests used to diagnose rectal cancer include the
following:
- Physical exam and 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.
- Proctoscopy: An exam of the rectum using a proctoscope, inserted into the rectum. A proctoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.
- 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.
| Enlarge | | | | 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. 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. The following tests may be used:
- Reverse-transcription polymerase chain reaction (RT-PCR) test: A laboratory test in which cells in a sample of tissue are studied using chemicals to look for certain changes in the structure or function of genes.
- Immunohistochemistry study: A laboratory test in which a substance such as an antibody, dye, or radioisotope is added to a sample of tissue to test for certain antigens. This type of study is used to tell the difference between different types 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
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 lymph nodes, nearby organs, or other places in the body).
- 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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