Influence of body mass index on survival in indolent and mantle cell lymphomas: analysis of the StiL NHL1 trial.

Obesity is a well-known risk factor for the development of cancer, but its influence on the course of disease is still controversial. We investigated the influence of body mass index (BMI) on overall survival (OS) in 502 patients with indolent non-Hodgkin's lymphoma or mantle cell lymphoma in a subgroup analysis of the StiL (Study Group Indolent Lymphomas) NHL1 trial. We defined a cut-off of 22.55 kg/m(2) by ROC calculation and Youden Index analysis and stratified patients into "low BMI" and "high BMI". Five-year OS was significantly longer in the high BMI group (82.2%) when compared to that of the low BMI group (66.2%) (HR 0.597; 95%CI 0.370-0.963; p = 0.034). BMI was also an independent prognostic factor for OS in multivariate analysis (HR 0.541; 95%CI 0.332-0.883; p = 0.014). Of note, patients had a significantly lower BMI in the presence than patients in the absence of B-symptoms (p = 0.025). BMI significantly impacts on OS in indolent non-Hodgkin's lymphoma and mantle cell lymphoma, which may be influenced by the effect of B-symptoms on BMI.