Gastrointestinal / Colorectal Cancer & Treatment Options

According to the American Cancer Society, an estimated 153,880 cases of colorectal cancer were diagnosed in 2008. This excludes another 272,170 cases for digestive system organs including the stomach, gall bladder, liver and small intestine. Colorectal cancer is the third leading cause of death among men and women alike.

Colorectal cancer can affect any portion of the colon and/or rectum:

• The colon which extends from the end of the small intestine to the rectum consists of the ascending, transverse and descending sections.
• The sigmoid colon is the lower part of the descending colon and leads into the rectum.
• The rectum makes up approximately the final five inches of the colon.

Risk Factors

Although the majority of colorectal cancers occur after the age of 50, the disease can arise at any age. Knowledge of family history and the following risk factors is important:

• Diet high in fat and red meat and low in fruits and vegetables
• Obesity
• Diabetes
• History of polyps in the colon, ulcerative colitis, Crohn's disease or colon cancer
• Personal or family history of a genetic syndrome known as hereditary non-polyposis colon cancer (HNPCC) or familial adenomatous polyposis (FAP)

Diagnosis

When symptoms occur, further evaluation may be necessary. Some symptoms of colorectal cancer include:

• Rectal bleeding
• Change in bowel habits
• General abdominal discomfort
• Unexplained weight loss
• Bloating
• Persistent tiredness
• Unexplained low blood counts

Special tests may be done to diagnose colorectal cancer. These may include:

• Physical exam with a digital rectal exam to assess the rectum for abnormalities
• Double-contrast barium enema
• Sigmoidoscopy, a thin, lighted tube which looks inside the rectum and sigmoid colon for abnormal areas or polyps that might be cancerous. (Although this test can be used to diagnose a low-lying rectal cancer, this test is most useful as a follow-up exam after treatment)
• Colonoscopy, which uses a longer lighted tube to view the inside of the rectum and entire colon for polyps or other abnormalities
• Virtual colonoscopy examines the entire colon and rectal passages by a CT scan of the abdomen that allows the radiologist to create computer images similar to those seen by a standard colonoscopy. (Although this test is able to visualize the colon, polyps cannot be removed or biopsied using this technique.)

During a sigmoidoscopy or colonoscopy some tissue may be removed and examined under a microscope to determine if cancer is present.

Treatment

The main treatments for colon and rectal cancers are surgery, chemotherapy and radiation therapy. Depending on the location and stage of the cancer two or more of these types of treatment may be recommended. They may be combined and administered at the same time or used one after another.

Surgery

Surgery is the main treatment for colon and rectal cancer. The type, extent and timing of surgery will depend on the location and stage of the tumor.

Chemotherapy

This involves the administration of anticancer drugs for certain stages of colon and rectal cancer. It may be delivered after surgery when there is no evidence of cancer, but a chance it may come back or to help shrink a tumor before surgery. Sometimes it will be given at the same time as radiation therapy.

Radiation Therapy

External beam involves a series of painless, daily (Monday through Friday) outpatient treatments delivered over approximately six weeks. It works by focusing a beam of ionizing radiation to the target area while sparing the surrounding tissue. The two main techniques for delivering external beam radiation are:

• 3-dimensional conformal therapy (3-D conformal) refers to a method of treatment delivery that incorporates 3-dimensional computer planning and treatment systems to produce a high-dose area of radiation that conforms to the shape of the area to be treated. This technique allows the delivery of precise doses of radiation to the targeted area through multiple treatment fields while sparing surrounding tissues.
• Intensity modulated radiation therapy (IMRT)* which utilizes a more sophisticated system of shields within the machine allowing a higher dose of radiation to be delivered to the area to be treated from multiple angles, while minimizing the effects on surrounding tissue. This form of 3-D conformal radiotherapy allows a precise adjustment of radiation beams to the tissue within the target area.          

                  *IMRT is appropriate for specialized circumstances only.

Treatment Side Effects

Side effects from these treatments may include mild skin irritation (similar to sunburn), fatigue, diarrhea, abdominal cramping, rectal and bladder irritation, urinary urgency and frequency. Most of these side effects will lessen after treatment is completed. When radiation therapy is combined with chemotherapy, low blood counts may also occur.