Colorectal Cancer

Colorectal cancer is the third most common cancer in American men and women. This year, the American Cancer Society estimates 146,970 new cases will be diagnosed in the U.S. Roughly 49,920 people will die from it.

The risk for colorectal cancer increases with age, with more than 90 percent of cases diagnosed after 50. Researchers estimate incidence of colorectal cancer is up to 23 percent higher in African-Americans than in whites. Death rates are up to 43 percent higher in blacks. Some other risk factors include: family history of colorectal cancer, personal history of polyps, inflammatory bowel disease, diet high in red and processed meats, lack of physical activity, obesity, smoking, excessive consumption of alcohol and type 2 diabetes.

Polyps and Colorectal Cancer Screening

Polyps are growths of abnormal tissue. Up to two-thirds of all polyps in the colon are a tissue type called adenomas. Adenomas are very common in people after 50 and the majority of them are benign. But a small number of them become cancerous. On average, it takes about 10 to 15 years for a polyp to develop into colorectal cancer. Therefore, health experts recommend screening and removal of polyps while they are still benign.

The main screening method for polyps and colorectal cancer is colonoscopy. In 2003, researchers estimate about 14 million colonoscopies were performed in the U.S. For patients at average risk, a colonoscopy is recommended every ten years, starting at age 50.

Colonoscopy is one of the most common medical procedures performed in the U.S. But it’s not a perfect screening tool. Many patients dislike the bowel cleansing preparation for the exam and/or are embarrassed by the procedure. Researchers estimate colonoscopy can miss 6 to 12 percent of colon polyps and about 5 percent of cancers. Incomplete removal of a polyp is believed to be a cause of up to 25 percent of colorectal cancers. In addition, the procedure is associated with an increased risk for complications, like bleeding, perforation or adverse effects of sedation.

A Vaccine to Prevent Colon Cancer

Most of the cancer vaccines under development are for people who already have cancer. For them, the treatment aims to help them fight the disease or prevent its recurrence. Researchers at the University of Pittsburgh Cancer Institute are testing a vaccine that may help reduce the risk of developing cancer in patients with advanced adenomas, a type of polyp that carries a high risk of becoming cancerous.

The vaccine under study targets a specific protein on polyps, called MUC1 (mucin 1). Although all polyps contain this protein, it’s somewhat altered in polyps that are abnormal and in those that turn into cancer. Gastroenterologist Robert Schoen, M.D., M.P.H., says the study aims to teach the body to recognize abnormal forms of MUC1 and, hopefully, attack those polyps. If it works, the treatment may prevent abnormal polyps from growing and turning into cancer.

Researchers are looking to enroll about 50 to 60 patients in the vaccine study. To qualify, patients must have a confirmed pathology report of an advanced adenoma. Participants will receive a total of three injections in the thigh over a ten week period. Blood samples will be taken at 12 weeks, 28 weeks and one year to measure immune response to the vaccine.

For general information on colorectal cancer:

American Cancer Society

National Cancer Institute