The notion of preventing breast cancer is exciting, but individual postmenopausal women should proceed cautiously when considering taking aromatase inhibitors, or “AIs” for this purpose. #buzzkill
Widely reported during the past week was a finding that “exemestane” --one of a class of drugs known as aromatase inhibitors, or “AIs” – “should be considered a new option for primary prevention of breast cancer.” The data were presented at the annual ASCO Conference and published simultaneously in the NEJM (available free).
Exemestane is the generic name of a medication made by Pfizer and marketed as Aromasin. It is one of three formulations of AIs currently available. They work by blocking the body’s ability to convert androgens into estrogen.
As it exists today the cost/benefit equation is flawed at both ends. We have an inadequate grasp of the true human cost of chemoprevention of breast cancer and in many cases an exaggerated (and unwarranted ) fear of breast cancer.
We cannot know with much accuracy who will benefit from exemestane and without accurate, specific determinants of high risk we may end up medicating too many people. The editorial accompanying the study’s publication in the NEJM was only slightly less giddy than the mainstream media coverage, noting “Key issues are the identification of high-risk cohorts and biomarkers that can predict response to a particular intervention.” However, NEJM failed to also call for research into identification and biomarkers that can predict, prior to treatment, which women are more likely to suffer adverse events.
I understand that quality of life was measured and found unaffected in the study. But breast cancer researcher Dr Susan Love reminded us:
Side effects, such as arthritis and joint pain, hot flashes, sexual problems, fatigue, and insomnia… were dismissed as not serious, but it should be noted that one-third of the women on exemestane stopped taking it during the three years of the study. (emphasis mine)
Before we “ask our doctors about” this pill, women need a more robust understanding of the potential health and lifestyle consequences of exemestane therapy. Doctors need to fully consider quality of life issues. Together, women and their doctors should make decision about chemoprevention that – like every therapy decision – are individualized to the greatest extent possible.