Correlation between serum prostate-specific antigen and cancer volume in prostate glands of different sizes

Objectives: To further evaluate the relationship of prostate-specific antigen (PSA) with prostate size and tumor volume in a contemporary surgical series. Although early studies showed a strong correlation between PSA and tumor volume, it has been suggested that PSA is no longer a valid marker for prostate cancer and only correlates with prostate size. Methods: From 2003 to 2009, 1234 men with data on prostate weight and total tumor volume underwent radical prostatectomy by a single surgeon. Prostate size was classified into tertiles: small (≤41.2 g), medium (41.3-54.5 g), and large (≥54.6 g). Pearson correlation coefficients were used to examine the relationship of PSA with prostate size and tumor volume across different prostate sizes. Results: Median preoperative PSA was 4.9 ng/mL (standard deviation ± 4.6), mean prostate size was 51.7 g, and mean tumor volume was 5.6 cm³. PSA had a significant correlation with prostate size only at a prostate weight ≥54.6 g (P = .02). Regardless of prostate size, PSA had a more robust significant correlation with tumor volume than with prostate size (all P <.0001). Conclusions: PSA was significantly correlated with prostate size only in the largest prostate glands, but was significantly associated with tumor volume in small, medium, or large prostates. Thus, PSA continues to be a better marker for tumor volume than for prostate size.