Rectal cancer often begins as small polyps, or adenomatous cells, in the rectum, which is the last part of the large intestine. Most polyps are benign or premalignant, but if undetected, some can become cancerous over time. Rectal cancer is often detected through age appropriate screening tests or to investigate symptoms such as those listed below.
Although rectal cancer rarely shows any symptoms during its early stages, there are warning signs:
change in bowel habits
blood in the stool
recurring stomach discomfort such as gas, cramping, or pain
weakness or fatigue
unexplained weight loss
Factors that may increase the risk of colon cancer:
inflammatory bowel disease such as ulcerative colitis or Crohn's disease
high-fat, low-fiber diet
family history of colorectal cancer or colon polyps
The risk of colon cancer also increases with age.
Screening and Diagnosis
A colonoscopy uses a colonoscope to visually examine the colon and rectum for polyps and tumors. A colonoscope is a thin, flexible tube, with a tiny fiber-optic video camera and a light inside its tip. It is about the thickness of an adult finger. The tube is flexible and can be maneuvered to investigate the interior surface of the colon. The camera sends magnified images of the colon to a television screen.
The colonoscope can be used to perform treatment as well as viewing the colon. Small surgical instruments, inserted through the colonoscope, can be used to remove small polyps that are discovered during the examination, without having to perform major surgery.
To prepare for a colonoscopy, a patient is usually required to drink a liquid or perform bowel cleansing using laxatives and sometimes enemas. This eliminates all fecal matter (stool) from the colon so that the person conducting the test will have a clear view.
A sigmoidoscopy is similar to a colonoscopy in that it uses a flexible tube with a fiber-optic camera and light, but examines only the last two feet of the intestine, called the sigmoid colon, and rectum.
A proctoscope is an office-based special plastic scope that allows your doctor to examine the lining of the rectum. It may require an enema to clean out the stool at the end of the digestive tract and allow improved visualization to detect problems in the rectum.
Rectal cancer staging tests estimate how far a particular cancer has penetrated into the colon, whether the cancer has spread to nearby lymph nodes or organs, and to determine the best method of treatment. Rectal cancer is most often staged prior to surgery with an ultrasound probe inserted into the rectum or with an MRI. This allows your doctor to make decisions on the potential need for chemotherapy or radiation before or after surgery, to minimize the chance of recurrence and provide the best possible chance of cure.
The most common staging system is called the TNM System (tumors/nodes/metastases). The "T" is for the degree of invasion of the intestinal wall, "N" for degree of lymphatic node involvement, and "M" for the degree of metastasis.
Surgery for Rectal Cancer
Surgery for rectal cancer involves removing all or part of the recutm. Most patients are able to have the digestive tract reconnected after surgery, though some patients may require a temporary or permanent bag for the stool. At USC, our surgeons are skilled in offering minimally invasive approaches to the treatment of rectal cancer and are able to reconnect the bowel in over 90% of cases. Only in the lowest lying tumors where a patient’s continence control would be compromised by removal of the anal sphincter complex will a permanent bag be required. A temporary bag may be needed for low lying tumors while the connection heals. This requires a second, smaller surgery to reverse this and usually occurs within three to six months of the first surgery. We also specialize in recurrent rectal cancer where a tumor may have grown back after an initial surgery requiring further treatment.