“I used to believe a mammogram saved my life.” So begins a remarkable article in this Sunday’s New York Times Magazine (“Our Feel Good War on Breast Cancer“), which asks provocative questions about the battle against breast cancer, questioning awareness efforts and saying mammography has not been as effective at reducing mortality as claimed.
We asked Otis W. Brawley, M.D., the Society’s chief medical officer for his thoughts.
“This is a powerful and important article, one I believe every breast cancer advocate, and frankly even advocates for prostate and other cancers, should read. It lays out the challenge that lies before us in reducing death and suffering from breast cancer, while demonstrating the challenge that we in public health face in how to accurately and truthfully administer information.
“In her article, Ms. Orenstein asks a stunning question: whether the mammogram she had even mattered, or whether her outcome would have been the same had she detected the cancer herself years later. She, like millions of American women who have been diagnosed with breast cancer, will never know the answer to that question.
“Many experts agree that not every breast cancer detected early will go on to cause serious disease and even death. But we do not yet have the means to predict whether a small localized tumor will grow or spread, or whether it will potentially remain small and never cause harm.
“There is considerable disagreement as to how many breast cancers actually are what we call ‘over-diagnosed.’ Studies have come up with estimates ranging anywhere from none of them to more than one in three. The most credible evidence suggests the rate of over-diagnosis is somewhere between ten and 20 percent.
“While the rate of over-diagnosis is unsettled, we do have a number of clinical studies that consistently show that appropriate treatment of early-stage breast cancer saves lives. Observation, what in prostate cancer has been termed ‘watchful waiting,’ is not appropriate for breast cancer. A woman who is diagnosed with breast cancer should always receive treatment.
“There is little question that over time we will continue to refine and improve our ability to determine which women are more or less likely to benefit from different approaches to screening and treatment. Genomic research has already proven valuable in identifying which women in certain groups are more or less likely to benefit from intensive chemotherapy, and it holds our best hope moving forward. This problem is due to the fact that our definitions of cancer are based on microscopic description from the 1850’s. It is only through additional research and clinical trials that we can develop a 21st century definition of breast cancer.
“Meanwhile, the view that mammography has only marginally reduced the rate at which women present with advanced cancer must be viewed with caution. Reductions in deaths from breast cancer are due to a number of factors, including increased awareness, the rise of mammographic screening, and better treatment. However, we do not and cannot know with precision today how much these contribute to decreasing deaths and at what proportion.
“There has been a 35% decline in the female breast cancer death rate since 1991. This decline is due to several factors: increased awareness; an increased openness that allows us to talk about breast cancer; and improvements in diagnosis and treatment. One can argue about the proportions contributing to the decline, but we can say mammography has clearly contributed to the decline in death rate.
“The Society believes existing evidence shows that the benefits of screening mammography every year beginning at age 40 outweigh the risks and harms, which are an unavoidable part of breast cancer screening. The Society also recommends that women have careful and thorough discussions with a health care professional as they consider screening, including the benefits, limitations, and potential for adverse events such as false positive findings and the possibility of over-treatment.
“Women should understand that breast cancer screening is imperfect, and does have limitations. Nonetheless, one can be ‘pro-screening’ without resorting to exaggeration or over promising its effectiveness. This is our challenge. We must be able to give women a choice regarding screening without condescension. And while clinical studies consistently show that breast cancer screening has significant limitations, including some over-diagnosis, we also know that mammography screening does save lives.”