Value of mammography questioned in large new study

A large new study suggests that mammograms may not save more women’s lives than physical breast exams alone, and in fact may lead to unnecessary treatment of small breast cancers that would likely pose no harm.

The Canadian study, published February 11, 2014 in British Medical Journal (BMJ), looked at 90,000 women over a period of 25 years. Researchers found the same breast cancer death rates both in women who had mammograms and physical breast exams and in women who had only the latter. The study also found that one in five cancers found by mammograms—and biopsied or treated with surgery, radiation, or chemotherapy—would not have posed a threat to the woman’s health.

Although previous studies had found a benefit to mammography, Mette Kalager, visiting scientist at Harvard School of Public Health (HSPH) and an epidemiologist and screening researcher at the University of Oslo—who co-authored an editorial in BMJ accompanying the study—told the New York Times that a reason for the new study’s findings could be that modern-day treatments like tamoxifen make it less important to find cancers early. She also said that women are now more aware of the dangers of breast cancer and thus more likely to detect lumps and seek treatment.

“It might be possible that mammography screening would work if you don’t have any awareness of the disease,” she said.

Kalager and her HSPH co-authors—Hans-Olov Adami, adjunct professor of epidemiology, and Michael Bretthauer, visiting scientist—wrote in BMJ that they agree with the authors of the Canadian study “that ‘the rationale for screening by mammography be urgently reassessed by policy makers.’ ”

Kalager spoke on the mammography controversy as part of a Forum at HSPH panel in March 2011. Watch the video.

Read the New York Times article

Read the BMJ editorial

Learn more

Routine mammograms may result in significant overdiagnosis of invasive breast cancer (HSPH release)