Percentage of positive prostate biopsies independently predicts biochemical outcome following radiation therapy for prostate cancer

BACKGROUND: This work aims to deinitely show the ability of percentage of positive biopsy cores (%PC) to independently predict biochemical outcome beyond traditional pretreatment risk-factors in prostate cancer (Pca) patients treated with radiotherapy. METHODS: A cohort of 2493 men belonging to the eUreKa-2 retrospective multicentric database on (Pca) and treated with external-beam radiation therapy (EBRT) as primary treatment comprised the study population (median follow-up 50 months). a COX regression time to prostatespecific antigen (PSA) failure analysis was performed to evaluate the predictive power of %PC, both in univariate and multivariate settings, with age, pretreatment PSA, clinical-radiological staging, bioptic Gleason Score (BGS), RT dose and RT adT as covariates. RESULTS: P statistics for %Pc is lower than 0.001 both in univariate and multivariate models. %Pc as a continuous variable yields an AUC of 69% in ROC curve analysis for biochemical relapse. Four classes of %Pc (1-20%, 21-50%, 51-80% and 81-100%) distinctly split patients for risk of biochemical relapse (overall log-rank test P<0.0001), with biochemical progression free survival (BPFS) at 5-years ranging from 88% to 58% and 10-years bPFS ranging from 80% to 38%. CONCLUSIONS: We strongly afirm the usefulness of %PC information beyond main risk factors (PSA, staging and BGS) in predicting biochemical recurrence after EBRT for PCa. The stratiication of patients according to %PC may be valuable to further discriminate cases with favourable or adverse prognosis.