Some experts claim that the widespread use of mammograms has led to many unnecessary—and toxic—treatments.
October 20, 2009You’re used to being admonished to get a mammogram once a year after the age of 40. But a new line of thinking, most evident in an article that appears today in the Journal of the American Medical Association
(and reported on the front page of The New York Times) questions the effectiveness of the screenings.
In the last 20 years, widespread use of mammograms has led to the detection of many early breast cancers, and appears to have saved many lives. But the increased diagnosis and treatment of early cancers has not much reduced the prevalence of advanced breast cancers. That presents a conundrum. If medical treatment really prevents early cancers from developing into advanced cases, we “should be pulling cases out of the future into the present,” Barry Kramer, MD, director of NIH’s Office of Disease Prevention told the National Cancer Institute’s Cancer Bulletin. “In other words,” writes the Cancer Bulletin article, “every breast cancer detected early on by mammography should equal one less cancer detected later on.”
And this, in fact, is pretty much what’s happened with cervical and colon cancers. Screening and the removal of abnormal tissue has led to a precipitous drop in the number of invasive cases occurring in the U.S.
So what's going on with mammograms? A growing number of experts believe that cases of breast cancer are being overdiagnosed; tumors are being treated that will not progress to advanced stages and that may even resolve on their own. A widely disputed Danish study suggests that one in three breast cancers are overdiagnosed. Other studies put the figure at anywhere from 5 percent to 32 percent.
“The current quandary stems from the focus of screening programs on improving test sensitivity, leading to potential tumor overdetection and overtreatment,” write the authors of the JAMA study, Laura Esserman, MD, MBA, Yiwey Shieh, both of the University of California, San Francisco, and Ian Thompson, MD, of the University of Texas Health Center, San Antonio. The authors propose that cancer researchers focus less on improving mammograms and more on finding markers that differentiate high-risk from low-risk tumors. The goal is to give toxic cancer treatments only to patients who really need it.
