Metastasis-directed Therapy Prolongs Efficacy of Systemic Therapy and Improves Clinical Outcomes in Oligoprogressive Castration-resistant Prostate Cancer

Abstract

Background: Available therapies for castrate-resistant prostate cancer (CRPC) confer minimal survival advantage; thus, there is interest in metastasis-directed therapy (MDT) for oligometastatic or oligoprogressive disease to improve outcomes. Here, we describe outcomes of oligoprogressive CRPC treated with stereotactic ablative radiotherapy (SABR).

Objective: To report outcomes of oligoprogressive CRPC treated with MDT using SABR.

Design, setting, and participants: Patients with oligoprogressive CRPC were retrospectively evaluated, and outcomes following MDT were reported. Outcomes were additionally compared with oligoprogressive CRPC treated with change in systemic therapy alone.

Intervention: SABR to oligoprogressive lesions.

Outcome measurements and statistical analysis: Outcomes of interest were time to prostate-specific antigen (PSA) failure, time to next intervention (TTNI), distant metastasis-free survival (DMFS), and overall survival. Survival analysis was performed using the Kaplan-Meier method, and univariable analysis and multivariable analysis (MVA) were performed.

Results and limitations: A total of 68 patients were included. After MDT, median time to PSA recurrence, TTNI, and DMFS were 9.7, 15.6, and 10.8 months, respectively. A total of 112 lesions were treated, and the cumulative incidences of local failure at 12 and 24 months were 2.1% and 13.8%, respectively. Factors associated with the risk of local recurrence on univariable analysis were age (hazard ratio [HR] 1.07, p = 0.03) and Gleason grade group (HR 2.20, p = 0.07). Compared with change in systemic therapy alone (n = 52), MDT (n = 31) was associated with improved median time to PSA failure (9.7 vs 4.2 months, p = 0.066)), TTNI (14.9 vs 8.8 months, p = 0.025), and DMFS (12.7 vs 8.9 months, p = 0.045), and remained associated with improved outcomes on MVA.

Conclusions: In a retrospective cohort of oligoprogressive CRPC patients, MDT was associated with favorable outcomes and improved cancer control as compared with change in systemic treatment alone. Future prospective trials are needed to confirm these findings.

Patient summary: In this report, we retrospectively analyzed outcomes of patients with oligoprogressive castrate-resistant prostate cancer treated with radiation therapy to progressing lesions. Our results suggest that treatment of these lesions with radiation therapy can result in sustained periods of disease-free survival and might add benefit in addition to systemic therapy at the time of progression. These results need to be verified in a prospective trial to identify the optimal integration of radiation therapy into metastatic castrate-resistant prostate cancer.

Keywords: Castrate-resistant prostate cancer; Metastasis-directed therapy; Oligoprogressive.

Fig. 1 –

Waterfall plot of PSA change following radiation therapy. PSA = prostate-specific antigen.

Fig. 2 –

(A) PSA failure, (B) time to next intervention, (C) distant metastasis-free survival, and (D) overall survival, for the whole population. MDT = metastasis-directed therapy; Mets = metastasis; PSA = prostate-specific antigen.

Fig. 3 –

(A) PSA failure, (B) time to next intervention, (C) distant metastasis-free survival, and (D) overall survival, stratified by the use of metastasis-directed therapy. MDT = metastasis-directed therapy; Mets = metastasis; PSA = prostate-specific antigen.