The interaction of body mass index and race in predicting biochemical failure after radical prostatectomy

Therapy (case series).

4

To examine the interaction of body mass index (BMI) and race in predicting biochemical failure (BCF) after radical prostatectomy (RP). The relative contribution of BMI and race to BCF after RP has not been well characterized.

From 1988 to 2008, 969 white and black men underwent RP and BMI data were available. In all, 168 (17.3%) were black and 801 (82.7%) were white men. BCF was defined as a post-surgery PSA level≥0.2 ng/mL on ≥2 measurements. Cox regression methods were used to model the relationship between race, BMI and BCF.

The 969 men had a mean age of 59.8±7.2 years. There was no significant difference in BMI between black and white men (P=0.32). The 5-year disease-free survival for black obese men was the lowest at 48%, compared with non-obese black (73%), obese white (82%) and non-obese white men (83%, P<0.001). BMI did not have a significant impact on BCF. In a multivariate analysis, black race remained an independent predictor of BCF [hazard ratio (HR)=1.76, P=0.01]. BMI does not affect the risk of BCF in black men differently than white men (P value for interaction 0.93).

Black race is an independent predictor of biochemical failure after adjusting for pathological factors. The impact of BMI on BCF did not vary among different races. These findings suggest that elevated BMI does not affect the BCF rates of black men more than in other races, and that other factors may influence the racial variability in disease-free survival and BCF risk.