Cancer of the rectum, also called colorectal or colon cancer, is a cancer that develops in the colon or rectum. Your rectum is located in the last few inches of the colon. Colon cancer normally begins as small polyps. Most cases of colon polyps are benign, but some may become cancerous, so all instances of polyps are tested for the presence of cancer cells. Some people experience symptoms of colon cancer, although many people do not.
The exact cause of colon cancer isn’t known; however, doctors have concluded that certain factors increase your risk of developing it, including:
- family history of colorectal cancer
- polyps in the colon
- a diet that is high in fat
- chronic ulcerative colitis
Most people with colon cancer will not know they have the condition until they are screened for it. This is because most cases have no symptoms. However, people who do experience symptoms may have the following:
- bleeding from the anus
- loose stool or diarrhea
- dark patches in the stool
- pencil-shaped stool
- abdominal discomfort
- unexplained fatigue
- loss of appetite
- weight loss
- pelvic pain
The symptoms of colon cancer mimic other conditions, so it’s best to see a physician if you have any concerns.
If colon cancer is suspected, your physician will give you a lower GI (lower gastrointestinal series) with a barium enema. This is an X-ray of your colon and rectum given after an enema containing a barium dye has been administered.
Your doctor might also suggest you have a colonoscopy. A colonoscopy is used to confirm the presence of colon cancer and to locate any polyps or tumors in the colon or rectum.
When a lower GI is performed, any abnormalities found will appear as dark shadows on the X-ray, so a colonoscopy is often used to confirm what abnormalities are present. A colonoscopy is also used to remove polyps.
If cancer is detected it can fall into 5 stages.
Stage 0 is the earliest stage of a cancer diagnosis. Abnormal cells are found in the inner walls of the colon. These cells could become cancerous and spread beyond this point.
Stage I, also called Dukes A colon cancer, is a cancer that’s spread beyond the inner walls of the colon and into the muscle layers in the colon.
At this stage of cancer, the tumor extends past the muscular wall of the colon and into the outer layer of the wall, which is called the serosa.
In stage III, the cancer has spread beyond the serosa and into the lymph nodes. The lymph nodes are small nodules that store and produce cells that fight infection in the body. In this stage, the cancer may also form tissue around or near the lymph node gland.
This is the most advanced stage of colon cancer. At this stage, the cancer has spread into various organs in the body, such as the lungs or brain.
There are four main treatments given to people with colon cancer— surgery, chemotherapy, radiation therapy, and counseling. Depending on what stage of colon cancer you have, you may be given a choice between several treatments or you may be advised to have more than one. Even after treatment, the cancer may return. Currently there aren’t any ways to determine if this will occur.
After being treated for colon cancer, you return to your doctor for follow-up care. During your appointments, your doctor will monitor your symptoms and order an imaging scan and blood tests.
Written by: April Khan and Matthew Solan
Published on Jul 25, 2012
Updated on Feb 15, 2013
Medically reviewed by George Krucik, MD