A recent Harvard study has rekindled fiery medical debate and has left many women confused about when to have mammograms. The researchers report that the vast majority of American women who die from breast cancer are unscreened—and half of these fatalities occur in women under 50.
To reduce this grim toll, the team urges that medical guidelines be changed to recommend annual screening, starting at 40. This strategy, they conclude, is “the best method for women to avoid death from breast cancer,” which claims the lives of about 40,000 American women every year. Over a lifetime, the disease strikes one in eight women.
In a scientific controversy that’s been dubbed the “a new salvo in [the] mammogram wars,” some experts have attacked the study as flawed, contending that it could leave women in their 40s needlessly anxious, worried or bewildered.
One criticism that’s been raised is that the study didn’t account for possible differences between women who opted for screening and those who skipped the test. For example, earlier research suggests that women who get mammograms tend to have higher incomes, better education and overall health, and greater access to care.
Therefore, they may be more likely to consult a doctor as soon as they felt a lump, leading to better outcomes, while their poorer, less educated sisters might be at greater risk for fatal disease simply because they delayed getting medical care.
Screening younger women for breast cancer has long been a contentious topic. Witness the firestorm of controversy ignited when the US Preventive Services Task Force (USPSTF) issued guidelines in 2009 that recommend against routine screening for women in their 40s. The task force recommends mammograms every two years for women ages 50 to 74.
“The USPSTF recommendations have created a lot of confusion, because women in their 40s don’t know if it’s safe to skip mammograms or not,” says Katherine Lee, MD, a breast specialist at the Cleveland Clinic’s Breast Center.
In earlier guidelines, the USPSTF had previously recommended that younger women be screened every one to two years. Screening guidelines from other medical groups, including American College of Obstetricians and Gynecologists and the American Cancer Society, recommend annual mammograms for women in their 40s, as does Dr. Lee.
The USPSTF guidelines are based on research showing that a much larger number of women in their 40s must be screened to prevent one breast cancer death, compared to women in their 50s or 60s.
Because younger women’s breast X-rays are harder to interpret, they are more likely to suffer such harms as anxiety-inducing callbacks for additional imaging or even biopsies when they don’t have cancer. And it’s also possible for mammograms to miss some cancers.
The task force concluded that the harms outweigh the benefits for younger women, but also stated that in the end, the decision whether to have mammograms should be made by women in consultation with their doctors.
In the new study, the Harvard Medical School team used “failure analysis” to analyze the value of mammograms, using the cases of 7,301 women diagnosed with breast cancer between 1990 and 1999 at Partners Healthcare hospitals in Boston. The women were tracked until 2007.
Of the 609 confirmed breast cancer deaths, 71 percent occurred in women who had not been screened. The women’s median age at diagnosis was 49. For women who died from any other cause during the study, the median age was 72.
“In premenopausal women, breast cancer tends to be biologically more aggressive, so it has sometimes spread to other parts of the body by the time it’s diagnosed,” Dr. Lee reports. The rapid progression of the disease in younger women may explain why 50 percent of the breast cancer deaths analyzed by the Harvard team occurred in women under 50.
Conversely, in older women, the disease often progresses relatively slowly, adds Dr. Lee.
The study reported a dramatic improvement in breast cancer survival associated with screening. In 1969, half of women diagnosed with the disease were dead 12.5 years later, compared with only 9.3 percent of women in the study, who were diagnosed in the 1990s.
"This is a remarkable achievement, and the fact that 71 percent of the women who died were women who were not participating in screening clearly supports the importance of early detection," said co-author Daniel Kopans, MD, of Harvard Medical School and Massachusetts General Hospital, in a statement.
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