Biomarkers and obesity in surgically treated patients with prostate cancer

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Background: Obesity is associated with poor outcomes in prostate cancer (PC). We explored if biomarkers for proliferation and estrogen signaling relate to obesity and surgical outcomes in PC patients (pts) treated by radical prostatectomy (RP). Methods: Pts with RP at a single institution between 1993 and 2002 were reviewed (1156 pts). The analysis subset included pts with full preoperative staging and anthropometric variables (541 pts). Clinical variables examined included: age, PSA, pre-operative hemoglobin (Hgb), ethnicity, and body mass index (BMI). Surgical outcomes included: estimated blood loss (EBL), Gleason score ≥ 7 (GS >7), extra-capsular extension (ECE), positive margins (MR+), and pathologic stage (pT2 vs. pT3/T4). Biomarkers examined in a convenience subset (n = 61) included proliferation index (Ki67% in cancer cells) and ERα positivity (nuclei staining ≥5% in cancer or peri-tumoral stromal cells). Obesity was defined as BMI ≥ 30 kg/m2. A step-wise logistic regression analysis was used to determine odds ratio (OR) in relation to obesity. Results: Mean ± standard deviation for pre-operative data included: age 62.7 ± 7.5 yrs; PSA 8.4 ± 6.8 ng/dl; Hgb 13.6 ± 1.8 g/dl; and BMI 26.5 ± 3.8 kg/m2. Pt reported ethnicities included: white (432 pts), Black/African-American (69 pts), Asian/Pacific Islander (20 pts), Hispanic (16 pts). BMI correlated highly with race (Kruskal-Wallis p = 0.002) and weakly with EBL (Spearman 0.11, p = 0.009) and Hgb (Spearman 0.15, p = 0.002). No correlation was observed between obesity and Gleason score. Regression models showed obesity was independently associated with ECE (OR 2.5, 95% CI 1.2–5.3) and pT3/T4 (OR 1.9, 95% CI 1.0–3.3). Biomarker analysis showed Ki67% correlated with GS >7, (Spearman 0.25, p = 0.048), but not BMI. No ERα positivity was noted in cancer cells. Stromal ERα positivity was noted in 21/30=70% of non-obese and 15/31=48% of obese pts (Fisher’s exact test p = 0.12). Conclusion: We confirm the association between obesity, ethnicity, and poor surgical outcomes. Biomarker analysis shows that obesity has no effect on proliferation index or tumor grade. However, we observe a trend towards down-regulation of stromal ERα expression in obese patients.

No significant financial relationships to disclose.