Session: MP29: Prostate Cancer: Advanced (including Drug Therapy) II
MP29-03: Multi-Institutional Analysis of Metastasis Directed Therapy With or Without Androgen Deprivation Therapy in Oligometastatic Castration Sensitive Prostate Cancer
Introduction: Several prospective trials in oligometastatic castration sensitive prostate cancer (omCSPC) have shown metastasis-directed therapy (MDT) can delay time to progression and initiation of androgen deprivation therapy (ADT) compared to observation. However, its use with ADT remains poorly studied. Here we report a multi-national, multi-institutional retrospective cohort of omCSPC treated with MDT to understanding the long-term outcomes of patients treated with MDT alone or in combination with ADT. Methods: Patients from 13 institutions with omCSPC ( < 5 lesions) were included. Patients treated with MDT with or without a defined course of ADT were included. Time to biochemical progression (ttBP) (nadir + 2 ng/dl for patients treated with radiation or increase above 0.2 ng/dl for surgery) was calculated using Kaplan-Meier method and stratified by treatment group (MDT alone vs MDT + ADT). Multivariable Cox regression was performed adjusted for variables found to be prognostic on univariate analysis. Results: A total of 263 patients were included (105 with ADT and 158 without ADT) treated between 2003 and 2018 with a median follow-up of 49.5 months with ADT and 54.5 months without ADT. The majority were metachronous (90%) and had bone lesions (60%). Median length of ADT use was 21.3 months (IQR 12.0-31.9). Patients who received ADT vs. no ADT had poorer prognostic features including 23% vs. 1% synchronous, and 55% vs 40% Gleason 8-10. ADT use was associated with a better 5-year rate of freedom from biochemical progression (51% (95% CI, 41%-61%) vs 11% (95% CI, 6% - 17%); p<0.0001). On multivariable analysis the use of ADT remained significantly associated with ttBP (HR 0.23 [95% CI 0.16 – 0.33], p <0.001). Other factors associated with longer ttBP were original diagnosis year (HR 1.11, p = 0.004), disease free years (HR 1.09, p = 0.02), and post-MDT PSA nadir (HR 1.1, p <0.0001). Conclusions: In this large multi-institutional cohort of patients with oligometastatic prostate cancer treated with MDT, the addition of concurrent ADT appears to be associated with a greater rate of freedom from BP, though a small group of patients will have sustained biochemical response with MDT alone. Future prospective trials are needed to identify the optimal way to integrate hormonal therapy (testosterone suppression and/or potent antiandrogens) with MDT. SOURCE OF Funding: Movember
