Use of combined androgen deprivation therapy with postoperative radiation treatment for prostate cancer: Impact of randomized trials on clinical practice

Abstract

Purpose: To assess the impact of RTOG-9601 and GETUG-AFU-16 on the routine use of combination androgen deprivation therapy (ADT) with postoperative radiotherapy (PORT) for prostate cancer (CaP).

Material and methods: Patients with localized CaP treated with radical prostatectomy (RP) and PORT with or without ADT at a comprehensive cancer center from January 2006 to June 2007 (Period 1 = P1), July 2011 to December 2012 (Period 2 = P2), and January 2017 to June 2018 (Period 3 = P3) were included. Clinicopathologic features and treatment characteristics were analyzed and compared. Multivariable logistic regression was used to assess prognostic factors and association with ADT use. Statistical tests were two-sided and a P value <0.05 was considered significant. To validate the findings, United States National Cancer Database (NCDB) and Surveillance, Epidemiology, and End Results (SEER) data were collected to assess rates of combined ADT and PORT from 2004 to 2015.

Results: Five hundred and two patients were included: 152 (P1), 185 (P2), and 165 (P3). PORT was most commonly delivered as early SRT (delivered >1 year post-RP with undetectable PSA or PSA >0.05 and ≤0.5 ng/ml) in all periods. The use of combination PORT and ADT increased over time: 14.5% (P1), 32% (P2), and 41% (P3) (P < 0.001). The proportion of patients that met eligibility criteria for either GETUG-AFU-16 or RTOG-9601 decreased from 47% (P1) to 35% (P3) (P = 0.04). International Society of Urological Pathology grade ≥4 (P < 0.002) and pre-PORT PSA >0.5 ng/ml (P < 0.001) were associated with use of ADT. Positive surgical margin status had a negative association (RR 0.5, P < 0.002). The NCDB demonstrated similar trends for use of combined ADT with PORT, increasing from 37% to 49% from 2004 to 2015.

Conclusion: The use of combined ADT with PORT increased over time. However, only a third of contemporary patients undergoing PORT are represented in the major trials supporting the evidence for combination treatment, highlighting the need to characterize the modern impact of this intensification strategy.

Keywords: Androgen deprivation therapy; Postoperative radiation; Prostate cancer.