Butter me up.
The Study: A pooled analysis of several randomized trials evaluated the association between BMI and survival specifically among patients with metastatic melanoma, and we're here to give you the skinny. Most of these patients received either targeted therapy (BRAF inhibitors), immunotherapy (CTLA-4 and/or PD-1 inhibitors), or cytotoxic chemotherapy (dacarbazine). About 60% were classified as overweight or obese, but it was unclear how many were just big boned. To everyone’s surprise, obese patients who received targeted or immunotherapy—but not chemotherapy—had much better overall and progression free survival than patients with normal BMIs. When analyzed as a continuous variable among men—but not women—higher BMI halved(!) the risk of death. The study obviously couldn’t investigate potential mechanisms, but several are offered up in the discussion. Ultimately, we have a long way to go in our understanding of the complex influences of hormonal, metabolic, and immunologic phenotypes on the efficacy of novel cancer therapies. Turns out the skinny here is to not be skinny.
Bottom Line: Among men with metastatic melanoma treated with targeted or immunotherapy, higher BMI (in a continuous fashion!) was paradoxically associated with improved survival.