March is Colon Cancer Awareness Month, and PAMF encourages patients to talk to their doctors about scheduling a colonoscopy – one of the most effective preventive tests in medicine.

"Periodic colonoscopy may reduce the risk of death from colon cancer by 75 percent," said Paul Rubinstein, M.D., head of the Department of Gastroenterology at the Palo Alto Center. "This is an enormous decrease in risk simply by having preventative screening exams."

During a colonoscopy, a gastroenterologist (a doctor specially trained to care for the digestive tract) uses a thin, flexible tube with a small camera attached to visually check the inside lining of the rectum and colon (large intestine). Colonoscopy can detect nearly all colon and rectal cancers and the polyps (growths) that can lead to such cancers.

A colonoscopy is especially important for patients who have never had the exam. "Patients receive about 90 percent of the benefit of colonoscopy during their first time," said Dr. Rubinstein. "This is because most colon cancers develop slowly over a decade or more, and the first test is typically where doctors find the majority of polyps or cancers."

Because PAMF’s gastroenterologists have been actively screening patients for colorectal cancer for years, the incidence of colorectal cancer among patients has fallen dramatically, said Dr. Rubinstein. "We diagnose colon cancer most often in people who have avoided screening," he added.

An individual’s risk for developing colon cancer depends on many factors, including:

• Age: After age 50, the chance of having a cancer or pre-cancerous polyp in the colon rises. Doctors encourage most people to begin having regular screening tests at this age, but some patients may need to have the test before age 50 because they have other risk factors.
  
• Family history: Having a first-degree relative, such as a parent or sibling, who has had colon cancer makes a person more likely to develop the disease too.
  
• Substance use: People who smoke or consume excessive amounts of alcohol may be at greater risk.
  
• Medical history: If a person has inflammatory bowel disease or if cancers or polyps were found in a previous colonoscopy, doctors will
  recommend more frequent testing.

A patient’s doctor will consider these factors when deciding how frequently that patient should be screened. For the majority of people who have no risk factors and are found to have no polyps, interval colonoscopy is recommended at 10 years, said Dr. Rubinstein.

Colon cancer is particularly dangerous because by the time someone develops symptoms such as abdominal pain, changes in bowel habits and blood in the stool, the cancer may have spread beyond the colon and is less curable. At present, colon cancer is the second leading cause of cancer deaths in the United States.

Colonoscopy is the best and most proven test for colon cancer, especially for detecting the pre-cancerous polyps that are found in about 25 percent of patients, said Dr. Rubinstein. However, sigmoidoscopy (an exam of the lower two feet of the colon) and fecal occult blood tests (testing for blood in the stool) are also proven screening methods for reducing colon cancer death rates. Sigmoidoscopy is recommended every five to 10 years, and fecal occult blood tests are most accurate when performed annually. PAMF’s primary care physicians can help patients evaluate the screening options and decide which will work best for them.

To learn more about colon cancer, including screening guidelines, visit PAMF's Guidelines for Colon Cancer Testing.