Oligoprogressive castration-resistant prostate cancer treated with metastases-directed stereotactic body radiation therapy: predictive factors for patients' selection.

Oligoprogression is defined as limited metastatic clone resistant to on-going systemic treatment that grows in a background of stable or responding systemic disease. Aim of the present study was to analyze oligoprogressive prostate cancer (PC) patients treated with stereotactic body radiation therapy (SBRT) during systemic treatment to identify predictive factors and improve patients' selection. We included PC patients treated with SBRT on a maximum of 3 sites of oligoprogression during systemic therapy.