Obesity linked to improved survival in male melanoma patients

Obese patients with metastatic melanoma live significantly longer than those with normal body mass indexes (BMI), according to a new study published in Lancet Oncology. The surprising association was mainly seen in male patients who were treated with targeted or immune therapy.

Jeffrey Sosman, MD, professor of Medicine in the Division of Hematology and Oncology, was a co-author of the study. Sosman is also head of the Melanoma Program and co-leader of the Transitional Research in Solid Tumors Program at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University.

Melanoma, a serious form of skin cancer, accounts for the vast majority of skin cancer deaths in the United States. Over the past decade, significant progress has been made in the treatment of metastatic melanoma—especially with the approval of novel targeted therapies and immunotherapies—but patient survival outcomes still vary widely.

In the current study, investigators wanted to better understand what factors might influence clinical outcomes. Obesity is a known risk factor for many diseases and has been linked to worse outcomes in several cancers. But the association between BMI and survival outcomes in patients with metastatic melanoma—particularly those treated with new targeted and immune therapies—was unknown.

The authors hypothesized that obesity would be linked to worse outcomes in patients with metastatic melanoma, given a number of associations between obesity and cancer-promoting pathways and therapy resistance.

In the study, investigators analyzed six independent clinical cohorts of 1,918 metastatic melanoma patients who had been treated with targeted therapy, immunotherapy or chemotherapy.

They discovered that, in fact, obesity was associated with improved outcomes, particularly in male patients who had been treated with targeted or immunotherapies. Obesity was linked to an almost doubling in overall survival in these men—although no such association was seen in female patients, nor in those treated with chemotherapy.

According to the authors, the findings support the idea of an "obesity paradox" in melanoma: a phenomenon seen in some cancers where obesity is associated with an increased risk of disease but also a survival advantage in some patients with established disease.

Further investigation is needed to better understand the biological mechanisms that might be behind this association, as well as the role of gender in the outcome differences, the authors note. Understanding the underlying mechanism may offer insight to develop better treatments.