This article addresses whether obesity impacts prostate cancer outcomes after radical prostatectomy. Previous studies reported inconclusive results on the relationship between BMI and biochemical recurrence, prostate cancer–specific mortality, and overall mortality after primary treatment, mainly due to limitations of short follow-up time. An advantage of the study by Chalfin and colleagues is that it analyzed a large sample of men (N = 11,152) treated in a single center who were followed for a median of 5 years. A higher BMI was associated with worse pathology and a higher risk for biochemical recurrence. Moreover, both overweight (HR, 1.36; P = .045) and moderate obesity (HR, 1.51; P = .04) were associated with prostate cancer–specific mortality. While moderate-to-severe obesity was not linked (HR, 1.58; P = .356)—which led the authors to conclude that BMI was not an independent predictor of prostate cancer–specific mortality—we view it differently. Specifically, as the moderate-to-severe obesity group only included 255 men, of whom only 4 died from prostate cancer, we submit that the lack of statistical significance is most likely the result of low power and not due to lack of true association. Thus, these data support that obesity is linked to prostate cancer–specific mortality after radical prostatectomy. Whether extreme levels of obesity carry similar (or greater) risks should be tested in even larger cohorts with longer follow-up.
Obesity is a modifiable risk factor associated with worse outcomes for many cancers, yet implications for prostate cancer are not well understood. Notably the impact of body mass index on long-term survival after treatment is unclear. We performed a retrospective cohort study on a large series of men who underwent radical prostatectomy to assess the impact of obesity on long-term biochemical recurrence-free survival, prostate cancer specific survival and overall survival.
MATERIALS AND METHODS
Between 1982 and 2012, 11,152 men underwent radical prostatectomy at a single tertiary referral center. Patients were stratified according to body mass index as normal weight (body mass index less than 25 kg/m(2)), overweight (body mass index 25 to less than 30 kg/m(2)), mild obesity (body mass index 30 to less than 35 kg/m(2)) and moderate/severe obesity (body mass index 35 kg/m(2) or greater), comprising 27.6%, 56.0%, 14.1% and 2.3% of the cohort, respectively. Covariates included age, preoperative prostate specific antigen, surgery year, Gleason score, pathological stage, surgical margin and race. Predictors of biochemical recurrence-free survival, prostate cancer specific survival and overall survival were identified using Cox proportional hazard models.
Median followup was 5 years (range 1 to 27). Actuarial 20-year biochemical recurrence-free survival for mild and moderate/severe obesity was 65% and 51%, respectively, compared to 76% for normal weight men (p ≤0.001). In a multivariate model obesity was a significant predictor of biochemical recurrence-free survival (mild HR 1.30, p = 0.002; moderate/severe HR 1.45, p = 0.028) and overall survival (mild HR 1.41, p = 0.003; moderate/severe HR 1.81, p = 0.033). However, only mild obesity was significantly associated with prostate cancer specific survival (HR 1.51, p = 0.040), whereas moderate/severe obesity was not (HR 1.58, p = 0.356).
Obese men have higher rates of biochemical recurrence than normal weight patients during long-term followup. Obesity at the time of surgery independently predicts overall survival and biochemical recurrence-free survival but not prostate cancer specific survival.
The Journal of Urology
Obesity and Long-Term Survival After Radical Prostatectomy
J Urol 2014 Oct 01;192(4)1100-1104, HJ Chalfin, SB Lee, BC Jeong, SJ Freedland, H Alai, Z Feng, BJ Trock, AW Partin, E Humphreys, PC Walsh, M Han