Comparison of tumor volume parameters on prostate cancer biopsies

Context.-Prostate biopsy reports require an indication of prostate cancer volume. No consensus exists on the methodology of tumor volume reporting. Objective.-To compare the prognostic value of different biopsy prostate cancer volume parameters. Design.-Prostate biopsies of the European Randomized Study of Screening for Prostate Cancer were reviewed (n= 1031). Tumor volume was quantified in 6 ways: Average estimated tumor percentage, measured total tumor length, average calculated tumor percentage, greatest tumor length, greatest tumor percentage, and average tumor percentage of all biopsies. Their prognostic value was determined by using either logistic regression for extraprostatic expansion (EPE) and surgical margin status after radical prostatectomy (RP), or Cox regression for biochemical recurrence-free survival (BCRFS) and diseasespecific survival (DSS) after RP (n = 406) and radiation therapy (RT) (n = 508). Results.-All tumor volume parameters were significantly mutually correlated (R2 . 0.500, P <.001). None were predictive for EPE, surgical margin, or BCRFS after RP in multivariable analysis, including age, prostate-specific antigen, number of positive biopsies, and grade group. In contrast, all tumor volume parameters were significant predictors for BCRFS (all P <.05) and DSS (all P <.05) after RT, except greatest tumor length. In multivariable analysis including only all tumor volume parameters as covariates, calculated tumor length was the only predictor for EPE after RP (P = .02) and DSS after RT (P = .02). Conclusions.-All tumor volume parameters had comparable prognostic value and could be used in clinical practice. If tumor volume quantification is a threshold for treatment decision, calculated tumor length seems preferential, slightly outperforming the other parameters.

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