Salvage Radiotherapy for Recurrent Prostate Cancer: Can the Prognostic Grade Group System Inform Treatment Timing?

Kae Jack Tay, Thomas J. Polascik, Lauren E. Howard, Joseph K. Salama, Ariel A. Schulman, Zinan Chen, Christopher Amling, William J. Aronson, Matthew R. Cooperberg, Christopher J. Kane, Martha K. Terris, Stephen J. Freedland

Research output: Contribution to journalArticle

Abstract

Purpose: In order to better time salvage radiotherapy (SRT) for post–radical prostatectomy biochemical failure, we examined the association between pre-SRT prostate-specific antigen (PSA) and PSA control as a function of the new prognostic grade group (PGG) system. Patients and Methods: Using the Shared Equal Access Regional Cancer Hospital database, we identified men after radical prostatectomy with PSA > 0.2 ng/mL and without cancer involvement of lymph nodes who underwent SRT alone. SRT failure was defined as post-SRT PSA nadir + 0.2 ng/mL or receipt of post-SRT hormone therapy. Men were stratified by pre-SRT PSA (0.2-0.49, 0.5-0.99, and ≥ 1.0 ng/mL). Multivariable Cox models were used to test the association between pre-SRT PSA and SRT failure, stratified by PGG. Results: A total of 358 men met the inclusion criteria and comprised our study cohort. Median post-SRT follow-up was 78 months. A total of 174 men (49%) had pre-SRT PSA 0.2-0.49 ng/mL, 97 (27%) PSA 0.5-0.99 ng/mL, and 87 (24%) PSA ≥ 1.0 ng/mL. On multivariable analysis among men with PGG 1-2, pre-SRT PSA 0.2-0.49 ng/mL had similar outcomes as PSA 0.5-0.99 ng/mL; those with PSA ≥ 1.0 ng/mL had higher recurrence risks (hazard ratio = 2.78, P < .001). Among PGG 3-5, PSA 0.5-0.99 ng/mL or ≥ 1.0 ng/mL had a higher recurrence risk (hazard ratio = 2.15, P = .021; and hazard ratio = 2.49, P = .010, respectively) versus PSA 0.2-0.49 ng/mL. Conclusion: In men with higher-grade prostate cancer (PGG 3-5), SRT should be provided earlier (PSA < 0.5 ng/mL), while among men with lower-grade disease (PGG 1-2), SRT results in equal PSA control up to PSA 1.0 ng/mL. Prior studies suggest that the timing of salvage radiotherapy (SRT) for recurrence after radical prostatectomy is grade dependent. We validated this finding using the prognostic grade group (PGG) system, which indicated that men with higher PGG (3-5) at diagnosis should receive earlier SRT (before prostate-specific antigen [PSA] reaches 0.5 ng/mL), whereas men with lower PGG (1-2) had no adverse impact when SRT was delayed until PSA was > 1 ng/mL.

Original languageEnglish (US)
JournalClinical Genitourinary Cancer
DOIs
StatePublished - Jan 1 2019

Keywords

  • Biochemical recurrence
  • Gleason
  • Radical prostatectomy
  • Sequence
  • Survival

ASJC Scopus subject areas

  • Oncology
  • Urology

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    Tay, K. J., Polascik, T. J., Howard, L. E., Salama, J. K., Schulman, A. A., Chen, Z., Amling, C., Aronson, W. J., Cooperberg, M. R., Kane, C. J., Terris, M. K., & Freedland, S. J. (2019). Salvage Radiotherapy for Recurrent Prostate Cancer: Can the Prognostic Grade Group System Inform Treatment Timing? Clinical Genitourinary Cancer. https://doi.org/10.1016/j.clgc.2019.05.007