On February 11, The New York Times published a provocative article entitled “Vast Study Casts Doubts on Value of Mammograms” detailing that “one of the largest and most meticulous studies of mammography ever done, involving 90,000 women and lasting a quarter-century, has added powerful new doubts about the value of the screening test for women of any age.” This study, published in the British Medical Journal, was summarizing a 25-year follow-up of the Canadian National Breast Screening Study, one of eight randomized controlled trials (RCTs) of screening mammography conducted in the 1970s and 80s.
This study data is certainly not new; it is no different from the data published at the six- and 11-year follow-up periods. Data from this trial have been widely criticized and differs significantly from other RCT’s of screening mammography in that it has shown no mortality reduction from population mammography screening. Discordant results obtained by this trial compared to others prompted multiple critical reviews of the data and revealed significant flaws in study methodology including lack of appropriate randomization procedures and significantly substandard mammography, even by the standards of the time. Proponents of screening mammography have convincingly argued that this data is so compromised that it should have no weight in determining policy as regards to screening mammography practice; our breast care experts at Huntsman Cancer Institute/University of Utah concur. Despite the controversy and the fact that the data from this disputed study effectively “waters down” the proven mortality reduction from breast cancer of mammography seen in other RCT’s, the data from this trial have been incorporated into all meta-analyses of screening mammography that currently inform policy.
Ultimately, challenges to the status quo of current practice are beneficial. Mammography screening is an effective public health initiative that has resulted in significant and reproducibly proven benefit to morality reduction from breast cancer. Marked improvements in technology and practice in the 30 to 40 years since the RCTs were conducted have resulted in lower false positive rates (so fewer women are called back for re-imaging and possible biopsy for benign findings), fewer false negative rates (so fewer cancers are missed), and lower radiation dose. Screening mammography is still not a perfect test by any measure, but it is the best we currently have. The Breast Care team at Huntsman Cancer Institute/University of Utah do not recommend any change from the current screening guidelines and practices because of this recent report. Nevertheless, this controversy is welcome as it will fuel the necessary innovation and scientific discovery that will improve breast cancer screening practices and ultimately benefit us all.
About the author:
Saundra Buys, M.D., is the Medical Director of High Risk Cancer Research at Huntsman Cancer Institute at the University of Utah Matthew A. Stein is the Section Chief of Breast Imaging in the Department of Radiology at the University of Utah School of Medicinecomments powered by Disqus