Bariatric Surgery Reduces Breast Cancer Incidence in a Prospective Trial

Abstract

In this issue of JAMA Surgery, Kristensson et al 1 build on their previous research using participants from the Swedish Obese Subjects Study (SOS), a prospective, controlled trial comparing bariatric surgery to usual care. The SOS investigators initially reported a decrease in cancer incidence after bariatric surgery in women, but not in men. 2 Subsequently, in the cohort of women participants, they reported that bariatric surgery reduced the incidence of female-specific cancers, particularly in those women who had hyperinsulinemia at baseline. 3 In this current study, women were followed up for a median of 23.9 years after bariatric surgery or usual care. The authors found a significantly lower incidence of breast cancer in the surgery group compared to the usual care group in premenopausal women and in women with elevated median insulin levels and insulin resistance at the time of enrollment. 1 This study is the first prospective study with long-term follow-up to report an association between bariatric surgery and a reduction in breast cancer incidence. While cancer incidence was not a prespecified end point and the SOS study was not randomized, a significant strength of the study is that both the surgery and usual care arm patients were eligible for bariatric surgery, which allowed for a more unbiased comparison of the 2 groups.