The optimal treatment approach for men with hormone-sensitive prostate cancer (HSPC) who develop oligometastatic disease is not well defined. While many of these patients receive androgen deprivation therapy (ADT) or observation, some studies have suggested that localized treatment with radiotherapy may be a beneficial alternative. In the phase II ORIOLE trial, stereotactic ablative radiotherapy (SABR) was compared to observation in 54 men with recurrent HSPC with 1 to 3 metastases who had not received ADT within 6 months of enrollment.
SABR was significantly more effective than observation in delaying further disease progression. At 6 months, 19% of patients treated with SABR had progressed, compared to 61% of patients undergoing observation (P = .005). The median progression-free survival (PFS) was not reached in the SABR group and 5.8 months in the observation group (HR 0.3, P = .002). A total of 16 patients treated with SABR had lesions outside the treatment field. The rate of progression at 6 months was higher in patients with lesions outside the target field compared to patients where all lesions were treated (38% vs 5%; P = .03). Rates of adverse events (AEs) were low in the SABR group and there were no AEs of grade 3 or higher.
The authors concluded that treating oligometastatic HSPC with SABR improves outcomes, including time to progression, compared to observation alone. While these results need to be confirmed in a larger trial, SABR may offer an alternative treatment for patients with oligometastatic disease who wish to delay initiation of systemic therapy.
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