Information on colorectal cancer screening

If you’re a man or woman over 50, chances are that you’ve been told about the importance of being checked for cancer of the prostate or breast. Finding some types of cancers at early stages (before they cause symptoms) may increase one’s chances of survival with proper treatment. What you may not know is that one in twenty adults will develop colorectal cancer (cancer of the large intestine) during their lifetimes. Even though this cancer is much more preventable through early detection than breast or prostate cancer, 57,000 people in the U.S. die from it every year.

There are three effective methods of screening for colorectal cancer: fecal occult blood testing (checking for microscopic evidence of blood in stool samples applied to specially treated cards), flexible sigmoidoscopy (visualizing the lower one-third of the large intestine), and colonoscopy (visualizing the entire large intestine, a procedure that is usually performed under anesthesia). The U.S. Preventive Services Task Force (USPSTF) recommends that all men and women undergo some form of periodic screening starting at age 50 and continuing until age 75, regardless of risk factors.

But what if you already know that someone else in your family has had colorectal cancer? In a 2005 article in the Annals of Internal Medicine, Dr. Glenn Eisen from the Oregon Health and Science University in Portland and Dr. David Weinberg from the Fox Chase Cancer Center in Philadelphia reviewed recommendations for screening patients with family histories of colorectal cancer and outlined recent developments in screening technologies.

If possible, your doctor will want to find out your affected relative’s age at diagnosis, location and number of lesions found, medical histories of second-degree and distant relatives, and a history of other family cancers. Most experts recommend beginning colorectal cancer screening at age 40 in patients with affected first-degree relatives, or (if earlier) 10 years before the relative’s age at diagnosis. In contrast to the multiple screening options available to average-risk persons, patients with family histories of colorectal cancer should undergo colonoscopy every 5 years. Newer screening technologies such as computed tomographic colonography (also known as “virtual colonoscopy”) and stool DNA testing have recently demonstrated promise but are not considered ready for “prime time” use, and are not covered by most insurance plans.

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Note: the above posting is adapted from an article I wrote in the March 15, 2006 issue of American Family Physician.