Prostate-specific antigen percentage: An early predictive tool after iodine-125 interstitial brachytherapy for prostate cancer.

BACKGROUND: After interstitial prostate iodine-125 brachytherapy (BT), prostate-specific antigen (PSA) evolution in time could predict overall biochemical relapse, but, considering the single patient, it is influenced by the presentation PSA amount and by the prostatic volume. It is also challenging to differentiate a PSA bounce from a biochemical relapse. PURPOSE: To determine the usefulness of PSA percentage (PP) defined as the rate between PSA presented by a patient at time "t" and the PSA that the same patient had presented at the time of diagnosis (t0) assumed as 100% in predicting biochemical relapse and in differentiating them from PSA Bounces. METHODS AND MATERIALS: We included 721 patients from Milan S. Raffaele Turro (399) and Lucca Campo di Marte (then S. Luca) Hospital (322). The mean age of patients was 66.5 years (range, 50-79). Mean followup was 150 months (range, 24-180). For each patient, PSA was recorded before and after iodine-125 BT, and PPs were calculated. Cox regression model, relative operating characteristic curves, and Kaplan-Meier regression model were elaborated, and a cutoff of 20% was defined. RESULTS: We observed that PP >20% is an independent variable highly associated with relapse risk (p < 0.0001) with a sensitivity of 79.7%, a specificity of 82%, and an hazard ratio of 12.1, since the 6 months of followup. A PSA increase above the nadir should be because of bounce (sensitivity and specificity of 81.4%, p < 0.0001) if patient had experienced at 6 months a PP <20%. CONCLUSIONS: PP might represent an early and useful tool, predictive of clinical outcome in patients after BT for prostate cancer.

Low dose rate brachytherapy (LDR-BT) as monotherapy for early stage prostate cancer in Italy: practice and outcome analysis in a series of 2237 patients from 11 institutions.

OBJECTIVE: Low-dose-rate brachytherapy (LDR-BT) in localized prostate cancer is available since 15 years in Italy. We realized the first national multicentre and multidisciplinary data collection to evaluate LDR-BT practice, given as monotherapy, and outcome in terms of biochemical failure. METHODS: Between May 1998 and December 2011, 2237 patients with early-stage prostate cancer from 11 Italian community and academic hospitals were treated with iodine-125 ((125)I) or palladium-103 LDR-BT as monotherapy and followed up for at least 2 years. (125)I seeds were implanted in 97.7% of the patients: the mean dose received by 90% of target volume was 145 Gy; the mean target volume receiving 100% of prescribed dose (V100) was 91.1%. Biochemical failure-free survival (BFFS), disease-specific survival (DSS) and overall survival (OS) were estimated using Kaplan-Meier method. Log-rank test and multivariable Cox regression were used to evaluate the relationship of covariates with outcomes. RESULTS: Median follow-up time was 65 months. 5- and 7-year DSS, OS and BFFS were 99 and 98%, 94 and 89%, and 92 and 88%, respectively. At multivariate analysis, the National Comprehensive Cancer Network score (p < 0.0001) and V100 (p = 0.09) were correlated with BFFS, with V100 effect significantly different between patients at low risk and those at intermediate/high risk (p = 0.04). Short follow-up and lack of toxicity data represent the main limitations for a global evaluation of LDR-BT. CONCLUSION: This first multicentre Italian report confirms LDR-BT as an excellent curative modality for low-/intermediate-risk prostate cancer. ADVANCES IN KNOWLEDGE: Multidisciplinary teams may help to select adequately patients to be treated with brachytherapy, with a direct impact on the implant quality and, possibly, on outcome.

Is prostate-specific antigen percentage decrease predictive of clinical outcome after permanent iodine-125 interstitial brachytherapy for prostate cancer?

OBJECTIVE: To determine the usefulness of prostate-specific antigen (PSA) percentage (vs. pretreatment value assumed as 100%) in prediction of biochemical relapse, after iodine-125 ((125)I) permanent brachytherapy for prostate cancer, to employ a parameter independent by the initial PSA amount and by the individual prostatic volume. METHODS AND MATERIALS: Our study included 133 patients, 102 still disease free (Group A) and 31 who experienced proven biochemical recurrence (Group B). PSA levels before and after (125)I brachytherapy were recorded, and PSA percentage vs. pretreatment values were calculated. Cox regression model, receiver operating characteristic curves, and Kaplan-Meier regression model with log-rank test were calculated. RESULTS: We observed that, in patients submitted to brachytherapy for prostate cancer, a PSA percentage >20% of pretreatment value is highly associated with relapse risk (p<0.0001) and that this association is strongly present since t=6 months of followup (p<0.0001), with a hazard ratio near to five times (4.965), a sensitivity of 72.4%, and specificity of 79.8% related to the chosen cutoff. DISCUSSION: Despite the amount of PSA is the only parameter that the clinicians can deploy to monitor patient's followup after permanent interstitial brachytherapy for prostate cancer, its evolution in time seems unable to predict early biochemical relapse as it is influenced by prostatic volume and initial PSA amount. CONCLUSIONS: Our data suggest that a PSA percentage >20% of pretreatment value at 6 months might represent an early, inexpensive, and useful predictive tool of bad outcome in patients after permanent brachytherapy.