Impact of obesity on clinical outcomes in hormone receptor-positive breast cancer: a systematic review.

Abstract

The relationship between obesity and prognosis of early breast cancer is complex. Increased levels of aromatase present in adipose tissue of obese postmenopausal women may lead to suboptimal suppression of systemic estrogens. However, studies have been mixed with respect to the association between use of aromatase inhibitors (AIs) and clinical outcomes in obese women with early breast cancer. We conducted a systematic literature review following PRISMA guidelines to examine the impact of obesity on the efficacy of AIs in early-stage hormone receptor-positive breast cancer. Primary outcome measures included disease-free survival, relapse-free survival, distant recurrence-free survival, breast cancer-free survival, and overall survival. Of 491 studies identified, eight studies met criteria for inclusion: three retrospective cohort studies, one prospective cohort study and four randomized controlled trials. Four studies limited eligibility to postmenopausal women. Percentage of obese patients in studies ranged from 10 to 30%. Two studies examined use of AIs alone while the remainder included patients treated with either AIs or tamoxifen. Five out of seven studies suggested a negative impact of obesity on AI efficacy. The results of our systematic review highlight a need for further research exploring the optimal endocrine therapies for obese women. There is insufficient evidence at present to recommend tailoring adjuvant endocrine therapy with use of specific AIs or for dosing modifications of AIs in this patient population.