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).

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:

• Being aged 40 or older.
• Having certain hereditary conditions, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC or Lynch syndrome).

 

Having a personal history of any of the following:

• Colorectal cancer.
• Polyps (small pieces of bulging tissue) in the colon or rectum.
• Cancer of the ovary, endometrium, or breast.
• Having a parent, brother, sister, or child with a history of colorectal cancer or polyps.
• 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.

 

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:

 

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.

 

Virtual Colonoscopy: A procedure that uses a series of x-rays called computed tomography to make a series of pictures of the colon. A computer puts the pictures together to create detailed images that may show polyps and anything else that seems unusual on the inside surface of the colon. This test is also called colonography or CT colonography.