External Beam Radiotherapy with a Brachytherapy Boost vs. Radical Prostatectomy in Gleason Pattern 5 Prostate Cancer: A Population-Based Cohort Study

Publication date: Available online 31 March 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Chenyang Wang, Amar U. Kishan, Mitchell Kamrava, Michael L. Steinberg, Christopher R. King
PurposePatients with prostate cancer (PCa) containing Gleason pattern (GP) 5 disease have a higher and earlier incidence of prostate cancer-specific mortality (PCSM) than general PCa patients. This affords the statistical power to compare PCSM outcomes between different treatment modalities even when restricting analysis only to patients treated in the modern era. The purpose of this work was to compare survival outcomes among patients with GP 5 PCa on needle core biopsy or transurethral resection of prostate (TURP) treated with extremely dose-escalated radiotherapy (exemplified by external beam radiotherapy with a brachytherapy boost [EBRT+BT]) versus radical prostatectomy (RP) in the modern era.Materials/Methods7,669 men diagnosed with GP 5 PCa from 2004-2013 who received EBRT+BT or RP were identified using the Surveillance, Epidemiology, and End Results (SEER) database. After propensity score matching to balance patient characteristic variables, PCSM was compared between modalities using a multivariate Fine and Gray competing risk model that accounted for other-cause mortality (OCM), with adjustment for age, race, GP, and clinical T-stage.ResultsPatients treated with RP were younger, had lower burden of GP 5, lower T-stage, and lower OCM than patients treated with EBRT+BT. After propensity score matching, there was no difference in PCSM between patients treated with RP and EBRT+BT (adjusted hazard ratio [AHR] 1.018, p=0.910). The cumulative 5-year PCSM incidence rates were 5.6% and 6.1% for patients treated with RP and EBRT+BT, respectively. Patients with primary GP 5 had significantly higher PCSM than those with secondary GP 5, regardless of treatment modality.ConclusionsFor patients with GP 5 PCa based on needle core biopsy or TURP, RP and EBRT+BT offer equivalent PCSM in a competing risk model after propensity score matching to balance differences in patient characteristics.

Teaser

Comparisons of outcomes for prostate cancer patients treated with radical prostatectomy (RP) versus dose-escalated radiotherapy exemplified by external beam radiotherapy with a brachytherapy boost (EBRT+BT) are limited by patient selection bias. Restricting analysis to patients with Gleason pattern 5 disease treated in the modern era, and after propensity score matching in addition to accounting for other-cause mortality via a competing-risk model, prostate cancer specific mortality is equal for patients treated with EBRT+BT and RP.


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