Body mass index was associated with upstaging and upgrading in patients with low-risk prostate cancer who met the inclusion criteria for active surveillance.

BACKGROUND: Obesity is associated with an increased risk of high-grade prostate cancer (PCa). The effect of body mass index (BMI) as a predictor of progression in men with low-risk PCa has been only poorly assessed. In this study, we evaluated the association of BMI with progression in patients with low-risk PCa who met the inclusion criteria for the active surveillance (AS) protocol.
METHODS: We assessed 311 patients who underwent radical prostatectomy and were eligible for AS according to the following criteria: clinical stage T2a or less, prostate-specific antigen level < 10 ng/ml, 2 or fewer cores involved with cancer, Gleason score ≤ 6 grade, and prostate-specific antigen density < 0.2 ng/ml/cc. Reclassification was defined as upstaged (pathological stage > pT2) and upgraded (Gleason score ≥ 7; primary Gleason pattern 4) disease. Seminal vesicle invasion, positive lymph nodes, and tumor volume ≥ 0.5 ml were also recorded.
RESULTS: We found that high BMI was significantly associated with upgrading, upstaging, and seminal vesicle invasion, whereas it was not associated with positive lymph nodes or large tumor volume. At multivariate analysis, 1 unit increase of BMI significantly increased the risk of upgrading, upstaging, seminal vesicle invasion, and any outcome by 21%, 23%, 27%, and 20%, respectively. The differences between areas under the receiver operating characteristics curves comparing models with and without BMI were statistically significant for upgrading (P = 0.0002), upstaging (P = 0.0007), and any outcome (P = 0.0001).
CONCLUSIONS: BMI should be a selection criterion for inclusion of patients with low-risk PCa in AS programs. Our results support the idea that obesity is associated with worse prognosis and suggest that a close AS program is an appropriate treatment option for obese subjects.