New Study Reveals Risks of Mammograms May Outweigh Benefits for Some

Results of a new study published by the Journal of the American Medical Association (JAMA) about the efficacy of discovering breast cancer through mammography screening were surprising given the widespread adoption of such screening in woman at earlier ages and more often intervals in the recent years. While breast cancer is the second leading cause of cancer death and the most common non-cutaneous cancer, the idea of reducing mammograms may seem counterintuitive. Yet, this study’s authors assert that because the risks of performing such screening could outweigh the benefits for some age groups, more nuanced determinations as to whether to screen for the cancer through the use of a mammogram is necessary. This is not the only recent analysis of mammography screenings that has yielded unanticipated findings about the results of these attempts at discovering breast cancer in women. A report that was published earlier in the year by the British Medical Journal (BMJ) also found that annual screenings in women of certain ages do not reduce the rate of mortality caused by breast cancer.

JAMA Study

The JAMA study examined mammography screening and the related mortality benefits and chief harms. Ultimately, the report concluded that because in some cases the harms of the screenings could outweigh the benefits, the decision to undergo that type of cancer screening should be based on an individualized analysis of each patient’s risk profiles and preferences. This recommendation was based on a finding that for certain age groups there were high recorded incidences of false-positive results. In particular, although the study found that mammography screening was associated with a 19 percent reduction of breast cancer mortality, for women between the ages of 40 and 50 who undergo screening for 10 years annually, the chance of a false-positive is 61 percent.

In 2009, the U.S. Preventative Services Task Force (USPSTF) reversed its previous recommendation of mammography screening once every one to two years for women beginning at the age of 40 and instead endorsed routine screenings once every two years for women 50 years of age and older. According to the JAMA study, the USPSTF enacted this change in their official position on the subject stating “the decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take into account patient context, including the patient’s values regarding specific benefits and harms.” The JAMA authors found that despite this changed recommendation in 2009, which was supported by several European studies’ results, many U.S. sources published reports that contradicted these findings and, since 2009, the U.S. practice of recommending consistent screenings for women beginning at age 40 has not been affected.

The JAMA study characterizes the incidence of false-positives as a risk that may outweigh the benefits of such screening partly due to the fact that it has been reported to cause increased anxiety and distress. However, the authors admit that such the significance of such a result is “debated and likely varies substantially by patient.” Another reported potential risk is over-diagnosis, which is described in the report as “the detection of a tumor by screening that would not have become clinically evident in the absence of screening” and which exposes the patient to the harms of treatment without the benefits.

BMJ Study

The February report released in the BMJ and authored by Canandian researchers compared breast cancer incidence and mortality rates in groups of women who received mammography screening with groups that did not undergo the same and revealed results similar to the JAMA analysis. That is, the BMJ study found that “annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available.” While some sources have called this study “controversial” not only have these results been confirmed by the JAMA study, the findings are also supported by the USPSTF 2009 paradigm shift. For further discussion of the February study, see this report.