Obesity paradox in prostate cancer: increased body mass index was associated with decreased risk of metastases after surgery in 13,667 patients

INTRODUCTION: Obesity might negatively affect prostate cancer (PCa) outcomes. However, evidence according to the associations between obesity and metastases-free survival after radical prostatectomy (RP) is still inconsistent.

METHODS: We relied on PCa patients treated with RP at the Martini-Klinik Prostate Cancer Center between 2004 and 2015. First, multivariable Cox regression analyses examined the impact of obesity on metastases after RP. Last, in a propensity score matched cohort, Kaplan-Meier analyses assessed metastases-free survival according to body mass index (kg/m2) (BMI) strata (≥ 30 vs. < 25).

RESULTS: Of 13,667 individuals, 1990 (14.6%) men were obese (BMI ≥ 30). Median follow-up was 36.4 month (IQR 13.3-60.8). Obese patients were less likely to exhibit metastases after RP (HR 0.7, 95% CI 0.5-0.97, p = 0.03). Similarly, after propensity score adjustment, obesity was associated with increased metastases-free survival (log rank p = 0.001).

CONCLUSION: We recorded the obesity paradox phenomenon in PCa patients. In particular, high BMI (≥ 30) was associated with decreased risk of metastases after RP, despite an increased risk being anticipated. Whether statin use might have affected the results was not assessed. Further research is needed to unravel the controversially debated association between obesity and PCa.