March 2007

Although colorectal cancer is the second leading cause of cancer deaths in the United States, many people still do not consider screening exams for the disease as critical as those for other types of cancer, such as breast or prostate. However, colorectal cancer is one of the most preventable types of cancer if a patient has regular screening exams, and is most treatable when caught in the early stages.

Colorectal cancer most often begins with polyps, which are small growths inside the colon or rectum. Some polyps can become cancerous over a 10- to 20-year period. It is during this period in which gastroenterologists can detect and remove polyps before they become cancerous. PAMF conducts about 6,000 colonoscopies on patients every year, and physicians find polyps in about 20 percent of patients, said Paul Rubinstein, M.D., head of the Department of Gastroenterology at the Palo Alto Clinic.

Colorectal cancer can be particularly deadly because people often do not have symptoms. Individuals with symptoms often are already at a stage of colorectal cancer that is less curable. This illustrates the importance of patients having screening exams to detect polyps before they become cancerous, said Dr. Rubinstein. When symptoms do occur, the most common are pain in the abdominal area, blood in the stool or very dark stool, or a change in bowel habits.

"The risk of colon cancer increases in people 50 years of age or older, and individuals are encouraged to begin having regular screening exams at that time," Dr. Rubinstein said, adding that regular screening exams every 10 years through colonoscopy beginning at age 50 may reduce the risk of colon cancer by about 75 percent. In addition, individuals whose parents, siblings or children have had colorectal cancer are at greater risk and should begin having screening exams earlier, he said.

Beyond family history, the other risk factors for colorectal cancer include a personal history of polyps or inflammatory bowel disease. Cigarette smoking and excessive alcohol consumption may also increase the risk of colon cancer.

Although colonoscopy is the most thorough screening test for colorectal cancer, sigmoidoscopy (an examination of the lower two feet of the colon) and fecal occult blood tests (testing for blood in the stool) are also proven screening methods. Sigmoidoscopy is recommended every five to 10 years, and fecal occult blood tests are most accurate when performed annually.

To increase the number of patients who have regular colon cancer screening exams, PAMF primary care physicians are working with gastroenterologists to raise awareness of colorectal cancer among patients. One way they are doing this is by seeking out high-risk or average-risk patients upon their 50th birthdays to encourage them to have screening exams, said Susan Smith, M.D., chair of PAMF's Quality Improvement Steering Committee.

"Patients can greatly decrease their risk by having early discussions with their physicians about risk factors and screening exams," said Dr. Smith.