The rectum is part of the colon (large intestine) in the digestive tract. It’s the last 10 inches or so of the colon and ends at the anus, which is the opening to the outside. Rectal cancer is cancer that grows in the rectum. It tends to happen more with older age, especially in men, and usually grows slowly. Most of the time, it starts as a small growth called a polyp.
The cause is unknown.
People may not have symptoms for a long time, especially if the growth is small. Sometimes, people have blood in the stools (bowel movements). The stool may be thinner than usual, because it squeezes past the cancer. People may also feel urges to have bowel movements, but nothing comes out.
The health care provider makes a preliminary diagnosis from a medical history, physical examination, and laboratory tests. The doctor will do a colonoscopy. The doctor puts a small flexible tube into the anus. The tube has a light at the tip, so the doctor can see inside the rectum and colon. It’s long enough to go into the whole colon. It also has a tool at the tip so the doctor can take a small sample of tissue (biopsy) to be checked with a microscope to see if it has cancer cells.
If cancer is found, the health care provider will do other tests to see if the cancer has spread. This is called staging. These tests include computed tomography (CT) of the abdomen (belly) and pelvis, x-rays, and blood tests.
Small polyps and very small rectal cancers may be removed during colonoscopy. Larger cancers will be removed by surgery. The type depends on the size and location of the cancer and how far it has spread. Anticancer medicines (chemotherapy) and radiotherapy may also be used to shrink the cancer. If the cancer is large, the doctor may have to remove the whole rectum and anus. If this happens, the doctor will do a colostomy. In this procedure, a pouch is made from the colon and comes out through the skin. Stool will come out into a small bag.
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