A group of health experts (US Preventive Services Task Force or USPSTF) revised the screening guidelines for breast cancer last year. Based on a systematic review of published evidence, women were recommended to have screening mammograms every two years rather than annually at an average risk in age group 50 to 74. They left it to the woman and her doctor to determine screening on the basis of their risk factors and harm vs. benefit preferences for women in the age group 40 to 49. This change sparked a firestorm fuelled by annual mammograms proponents and those concerned that insurance companies would need co-payments.
Recent simulation studies funded by the National Institutes of Health (NIH) have confirmed that screening mammograms in age group 50 to 74 is most efficient once every two years for average risk women. Screening would provide the same benefit for these women annually, but would increase the rates of false positives, benign biopsies, and over-diagnosis. This also applied to younger women, even though they were at an increased risk of 2 to 4 fold. So the question becomes, what should an annual screening option for women do? Every other year, one strategy could be to consider additional and alternative tests.
While additional tests such as ultrasound have high false positive rates resulting in benign biopsies, due to lack of radiation exposure, it may be a safer option for the "off" years. A recent modelling study (funded by the National Cancer Institute) has shown that while 100,000 women avert 968 deaths from annual mammogram screening, it can induce 125 cases of breast cancer that lead to 16 deaths. For women with large breasts, this number doubles which requires additional views resulting in increased exposure to radiation. For women with dense breast tissue, an additional test strategy would definitely be better as ultrasound was known to detect cancers missed by mammography.
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