Stereotactic ablative radiotherapy in castration-resistant prostate cancer patients with oligoprogression during androgen receptor-targeted therapy

Objectives To report outcomes of stereotactic body radiotherapy (SBRT) in metastatic castration-resistant prostate cancer (mCRPC) patients with oligoprogression (<= 5 metastases) during first-line treatment with androgen receptor-targeted therapy (ARTT). Patients and methods Retrospective multi-institutional analysis of mCRPC patients treated with SBRT to oligoprogressive lesions during ARTT. End-points were time to next-line systemic treatment (NEST), radiological progression-free survival (r-PFS) and overall survival (OS). Toxicity was registered according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Survival analysis was performed using the Kaplan-Meier method, univariate and multivariate analysis (MVA) were performed. Results Data from 34 patients were analyzed. Median NEST-free survival, r-PFS, and OS were 16.97, 13.47, and 38.3 months, respectively. At MVA, factors associated with worse NEST-free survival and r-PFS were polymetastatic burden at diagnosis of metastatic hormone-sensitive disease (hazard ratio [HR] 3.66, p = 0.009; HR 3.03, p = 0.034), PSA <= 7 ng/ml at mCRPC diagnosis (HR 0.23, p = 0.017; HR 0.19, p = 0.006) and PSADT <= 3 months at mCRPC diagnosis (HR 3.39, p = 0.026; HR 2.79, p = 0.037). Polymetastatic state at mHSPC diagnosis was associated with a decreased OS (HR 4.68, p = 0.029). No patient developed acute or late grade >= 2 toxicity. Conclusion Our results suggest that SBRT in oligoprogressive mCPRC is safe, effective and seems to prolong the efficacy of the ongoing systemic treatment positively affecting disease progression. Prospective trials are needed.

Automated summary

A retrospective multi-institutional analysis of 34 mCRPC patients treated with SBRT during ARTT showed that SBRT for oligoprogressive lesions was safe and effective, prolonging NEST-free survival, r-PFS, and OS without significant toxicity. Further prospective trials are warranted.