Blog | Wednesday, March 12, 2014

Mammograms under fire in new study: trash the study?

Sometimes, we play a little politics on this blog. I am a student of current events and enjoy following the dysfunction and absurdities in American politics. To paraphrase the legendary former British Prime Minister: never has so little been done by so many to benefit so few.

Which of the following recent events is the most politically charged?
• Speaker of the House John Boehner passed a clean extension of the debt limit without conditions. (Nothing like a colossal failure on this issue months ago to guide the speaker today.)
• Obamacare received its 27th extension, another “tweak”.
• A new study questions the value of mammography.

Readers know how skeptical I am about medical dogma. When I was an intern a quarter century ago, I didn’t grasp why routine measurement of prostate specific antigen (PSA) was standard medical practice since it was true back then that more men were harmed than helped by its use.

A recent study in the prestigious BMJ has concluded that mammography does not save lives. This study will become political dynamite as breast cancer is as much a political issue in this country as it is a medical subject. Remember Mammogate?

I have no agenda here beyond a search for the truth. I favor any reasonable endeavor that will prevent disease, treat illness effectively and deliver comfort. If persuasive scientific information informs us that a medical treatment or test is not effective or is harmful, our reaction should not be to attack the test as flawed. We should also note if the criticizers have a personal stake in the test’s survival. When colonoscopy is supplanted by a better test, which it will be, gastroenterologists will need to separate our own interest from the public interest, in accordance with our professional ethical standards and the oath that we all took.

This new view on the old breast test mammography emerged from a randomized trial, which is a rigorous method of scientific study. Ninety thousand women participated. When there are a large number of subjects in a medical study, it strengthens the conclusions for mathematical reasons. This is why investigators strive to recruit a large number of patients in their studies. The BMJ study concluded that women who underwent mammograms had the same death rate from breast cancer as women who only underwent breast examinations. Additionally, “non-invasive” mammography led to unnecessary invasion on many women. Twenty percent of cancers found were felt not to be a medical threat and yet led to surgery and other unpleasant treatments.

Even when prior mammography data is viewed in its most optimistic light, the benefit to an individual woman is extremely modest. This point is so often misunderstood by even an informed public. When a study performed on a large population shows a 10% benefit, for example, the benefit to an individual participant may be trivial. This is why headlines such as “New Drug Strengthens Bone Density by 20%” are so deceptive. Patients need to know what the benefit of a particular treatment is for them, not for a large study group.

Get ready for the Mammography Zealots to mobilize for their 3-pronged approach: pitchforks, placards and protests!

My question for them is; Do they want to save mammography, or save women?

This post by Michael Kirsch, MD, FACP, appeared at MD Whistleblower. Dr. Kirsch is a full time practicing physician and writer who addresses the joys and challenges of medical practice, including controversies in the doctor-patient relationship, medical ethics and measuring medical quality. When he's not writing, he's performing colonoscopies.