Contributed by Sentara
Recently, conclusions from the Canadian National Breast Screening Study (Miller, et al), published in the British Medical Journal, have drawn national attention. Unfortunately, the study offers misleading conclusions based on the analysis of a historically flawed study that has been widely discredited by experts in radiology and breast health.
As a fellowship-trained diagnostic breast radiologist, I have been invited to comment on and review a variety of research and a multitude of data demonstrating the benefits of annual mammograms for women over the age of 40. In addition, I have over 20 years of first-hand experience, seeing my patients benefit from earlier detection through screening mammography. I, along with my colleagues at the Sentara Northern Virginia Comprehensive Breast Center (SNVCBC), agree that such a study should not be considered for any breast cancer screening policies and should be viewed with skepticism by women across the globe.
Why disregard the study?
The short answer is that the study was flawed when it was first conducted. At least seven other contemporary studies demonstrated a significant decrease in breast cancer deaths for women screened with mammography.
Why didn’t the study cited in the British Medical Journal show the same benefits as other studies?
There are several reasons, but the two major flaws of the study include are as follows:
- The mammograms were poor, disturbingly poor, even for the day. Many radiologists invited to participate in this study withdrew – citing quality concerns. In spite of these concerns, the study went on. The mammography units were second hand, and there was no use of “grids” while taking the images, which are essential in mammography to reduce blurriness. The positioning (1 view only versus standard 2 views) and technique were considered inadequate by the standards at that time. Technologists and interpreting radiologists were untrained. Even the physicist for the study agreed that the quality was “far below the state of the art.” The study revealed that only around 30% of cancers were detected by mammography, a statistic that is indicative of the poor quality equipment and technique. Quality mammography should detect at least twice that amount.
- The study was not randomized, as is required for legitimate results. Remarkably, symptomatic patients were allowed to be assigned to the mammography screening arm, invalidating the results.
Today, mammography has further evolved from high quality film screen to digital mammography aided by tomosynthesis (3D mammography). Dedicated breast imagers and fellowship training in breast imaging, along with quality standardization by federal law (the Mammography Quality Standards Act) have improved care and strengthened mammographic effectiveness. The Canadian study, needless to say, would not have passed standard quality testing. These modern techniques are revealing more cancers during the early stages, thus helping to reduce the number of breast cancer deaths by over 30%. These results apply to all age groups screened – including women in their 40s. Twenty-five percent of breast cancers occur in women in their 40s. Women who get breast cancer in their 40s also represent the greatest number of breast cancer deaths and the most years of life lost to breast cancer, which is why the American College of Radiology continues to support its recommendation of annual mammograms for all women over the age of 40. I steadfastly agree. Mammography’s demonstrated positive outcomes from the 1990s to today cannot be overstated, and women need to be properly informed about mammography and its benefits. A frightening proposition would be for women today to delay getting annual mammograms at age 40 because of a flawed study.
Mortality questions aside, what about morbidity? This study is callously silent on the issue of the worsened impact on treatment options – morbidity – for women who did not get mammograms but were found to have breast cancer by physical examination.
My colleague, Dr. Negar Golesorkhi, a fellowship-trained board certified breast surgeon with SNVCBC, further emphasizes the implications, noting the higher morbidity of women who do not get mammograms. While breast cancer treatment has improved over the years, survivorship increases substantially when cancers are detected earlier allowing for less extensive treatment. Additionally, earlier detection of breast cancer permits the multidisciplinary cancer team to offer women more options in surgical and radiation therapies. Women who do not get mammograms are often faced with advanced breast cancer, requiring chemotherapy, mastectomies and likely radiation therapy.
My colleagues and I have chosen to spend years researching, training and working in the field of women’s health because we care about the health of women and the quality of their lives. We want to make sure that we clarify misleading information and dispel myths around women’s health so women are properly equipped to make informed decisions about their health.
Rebecca A. Zuurbier, MD
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