Nevertheless, in such cases patients typically undergo invasive procedures such as surgery, radiation therapy, hormonal therapy and chemotherapy, said H. Gilbert Welch, a coauthor of the study and a professor at the Geisel School of Medicine at Dartmouth College. “These are major medical interventions and they’re certainly not something you would want to undergo if you didn’t need to,” he said.
The researchers also concluded that today’s sharply lower death rate for breast cancer is mainly due to factors such as improved treatments rather than early detection through mammograms.
The new study immediately fueled the already fierce debate over how often women should get mammograms, a controversy that has embroiled policymakers, politicians and physicians, as well as their female patients.
The American Cancer Society warned that the study “must be viewed with caution.” The American College of Radiology attacked the validity of the study, charging that it was spreading “misinformation” and “the cost may be lost lives.”
The report is the latest study to undermine the once-strong consensus that regular screenings are crucial to safeguarding women’s health. Just in the past two years, a major study of Norwegian breast cancer patients found that routine mammograms reduced the risk of dying from breast cancer by less than 10 percent. Another study found no effect on death rates when comparing European nations where screening became prevalent in the 1990s with those where it became widespread in the 2000s.
Even before those findings, in November 2009, a key federal panel revised its guidelines on mammograms to say that women should begin regular screenings at age 50 rather than age 40, and then get the exam every other year rather than annually.
However, that revision by the U.S. Preventive Services Task Force, made as Congress was crafting the new health-care law, was assailed not only by groups such as the American Cancer Society and the American College of Radiology but also by the Obama administration.
In 2010, lawmakers tweaked a mandate in the health-care law requiring insurers to cover preventive services recommended by the task force free of charge. The law specifies that when it comes to mammograms, insurers must follow the task force’s old guidelines.
Wednesday’s study analyzed changes in the rates of early- and late-stage breast cancer in the United States over time.
The authors’ premise was that if screening were effective, its growing use would result in greater detection of early-stage breast cancers and a corresponding drop in the prevalence of late-stage cancers.