Cancer Screening: Doing More Harm than Good? (page 3 of 3)

Mammograms also offer a smaller benefit than many patients -- and doctors -- assume. Mammography's effectiveness has been hotly debated, but a carefully conducted 2005 analysis suggests it cuts the risk of dying of breast cancer by 15 percent, says the NIH's Kramer. That means a 60-year-old who gets regular mammograms shaves her risk of dying of the disease in the next decade from 7 per 1,000 to 6 per 1,000.

As for colonoscopy: It allows the doctor to remove polyps, growths that can turn into cancer. The best estimates suggest that colonoscopy can cut the risk of death from colon cancer by as much as 60 percent. (We don't know for sure if it reduces the risk of death, because those studies haven't been done.) Sixty percent sounds great, until you realize that the chances of dying of colon cancer aren't all that big to start with. The average woman has a 2.1 percent risk of dying of colorectal cancer. (So of all the things that can kill her, this will be the culprit about 2.1 percent of the time.) The average man's risk is a little higher, about 2.3 percent. Knocking a 2.3 percent risk down by 60 percent means it drops to 0.9 percent -- a benefit, yes, but not necessarily big enough to outweigh all other considerations.

To Screen or Not to Screen

The fact is, there's no single answer. It depends on many factors, including how old you are, what other diseases you have, and what you value most in terms of your health. Dennis Fryback, PhD, is a former member of the U.S. Preventive Services Task Force, a group of experts convened by the federal government to make recommendations about screening. The task force recommends colonoscopy every ten years for people between the ages of 50 and 75, yet the 61-year-old Fryback has concluded it does not make sense for him to get screened.

He came to that decision in part because he has no family history of colon cancer. If he did, his chances of getting it would increase, and so would the odds he'd benefit from the test. He also knows that getting the exam requires at least a day of taking laxatives to clean out the colon and then facing the possibility of a perforation from the procedure, a risk that goes up with age. He balanced the possible reduction in his chances of dying of colon cancer against his other health problems. He had a heart attack last year and suspects he will die of heart disease before a colon polyp has a chance to kill him.

Given his circumstances, Fryback figures, colonoscopy "is like an expensive lottery ticket. I might get some extra time, but chances are much better that I won't get anything. It's like paying, say, $5 to have a very long-shot chance at a few hundred dollars."

When looking at his odds, Fryback has an advantage: He's an expert in medical decision making. Most of us, of course, are much less familiar with medical statistics, but there are tools to help average patients come to a decision that's right for them. Called patient decision aids, these tools come in the form of brochures, videos, and Web-based interactive programs; some include interviews with cancer survivors and people considering getting screened, who discuss their own decisions. Patients can sometimes take them home to study at their own pace.

Decision aids aren't widely available yet, but some insurance companies and a handful of medical centers offer them. Suzanne Bull used a patient decision aid DVD before opting to undergo radiation treatment for her breast cancer. "Watching it was the best thing I did," she says.

Eventually, researchers and doctors hope, better screening tests will be able to distinguish between cancers that need to be treated and those that don't. But until then, many experts believe, the decision to get screened should rest on an individual's values and his or her ability to handle uncertainty. "We have come to fear dying from disease more than dying at the hands of overzealous doctors," says Dartmouth's Dr. Black. The fact is, both are risks when we get screened for cancer.

Check out these books, which help with decisions about testing and treatment:

• Should I Be Tested for Cancer? by H. Gilbert Welch, MD
• Know Your Chances: Understanding Health Statistics by Steven Woloshin, MD, Lisa M. Schwartz, MD, and H. Gilbert Welch, MD

Special for our readers: View video cancer screening decision aids from Health Dialog at healthdialog.com.

Shannon Brownlee is the author of Overtreated: Why Too Much Medicine is Making Us Sicker and Poorer and a senior fellow at the New American Foundation, a nonpartisan think tank.

How to decide: Is screening right for you?
In the pipeline: Advances in cancer screening
Beyond cancer: 3 other ways you could be overtreated
Visit the Living Healthy blog for a guest post by Shannon Brownlee and ask your questions about cancer screening tests in our forum.

From Reader's Digest - April 2009

 

• • National Health Care
• • Colon Cancer
• What Matters to Me
• • Medical Dramas
• Breast Cancer
• Cancer

• In the Pipeline:
  Better Cancer Screening
• Researchers are working to come up with smarter tests to distinguish aggressive cancers from ones that can safely be left alone. Learn how.
• 
• 3 Other Ways You May Be Overtreated
• Screening tests aren't the only medical "miracle" that may be overused.
• 
• Screening Tests:
  Are They Right for You?
• Factors to consider before you schedule a cancer screening test.
• 

• Be Inspired
• 10 Celebrities Who Give Back
• 7 Amazing Stories, $700,000 to Charity
• Virginia Cervasio: Making It Matter
• PLUS:
• Quiz: What's Your Celebrity Cause IQ?