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).
See the following PDQ summaries for more information about rectal cancer:
- Gastrointestinal Stromal Tumors Treatment
- Colorectal Cancer Prevention
- Colorectal Cancer Screening
- Genetics of Colorectal Cancer
- Unusual Cancers of Childhood
Age and family history can affect the risk of 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. Talk with your doctor if you think you may be at risk. The following are possible risk factors for rectal cancer:
- Being aged 40 or older.
- Having a personal history of any of the following:
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:
- 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.
- 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.
- 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:
- 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).