Subcutaneous Fat Distribution is a Prognostic Biomarker for Men with Castration Resistant Prostate Cancer

Purpose: The relationship between body fat distribution and survival remains unclear in patients with castration resistant prostate cancer treated with docetaxel and androgen receptor axis targeted agents. We investigated whether body composition parameters could predict radiographic progression-free and cancer specific survival in patients with castration resistant prostate cancer. Materials and Methods: In this multicenter retrospective study we evaluated data on 282 consecutive patients diagnosed with castration resistant prostate cancer between September 2009 and March 2017. The subcutaneous fat index, the visceral fat index and the skeletal muscle index at the diagnosis of castration resistant prostate cancer were determined by computerized tomography data. Survival analyses were performed using the subcutaneous fat, visceral fat and skeletal muscle indexes dichotomized at 39.9, 58 and 52.4 cm(2)/m(2), respectively. Results: At the diagnosis of castration resistant prostate cancer, cancer specific survival was independently predicted using prostate specific antigen levels, Gleason score 8 or greater, performance status, a shorter interval from androgen deprivation therapy to castration resistant prostate cancer and a subcutaneous fat index of less than 39.9 cm(2)/m(2). During the median followup of 16.0 months patients with a subcutaneous fat index of 39.9 cm(2)/m(2) or greater received more docetaxel cycles than patients with a subcutaneous fat index of less than 39.9 cm(2)/m(2). Compared to patients with a subcutaneous fat index of less than 39.9 cm(2)/m(2) those with an index of 39.9 cm(2)/m(2) or greater had better 1-year progression-free and 2-year cancer specific survival (p = 0.009 and 0.021, respectively). Conclusions: Patients with a subcutaneous fat index of 39.9 cm(2)/m(2) or greater at the diagnosis of castration resistant prostate cancer showed higher progression-free and cancer specific survival rates than those with a subcutaneous fat index of less 39.9 cm(2)/m(2) at diagnosis. The subcutaneous fat index determined by computerized tomography data could serve as a useful objective prognostic factor to discuss patient therapeutic options. Further studies are needed to define the roles of each body composition parameter in relation to pharmacokinetics and oncologic outcome.