Radiotherapy as metastasis-directed therapy for oligometastatic prostate cancer

To summarize the available literature regarding radiotherapy as a metastasis-directed therapy (MDT) in the treatment of oligometastatic prostate cancer (PCa).

Three different clinical scenarios of oligometastatic PCa exist in which MDT can be applied: de novo oligometastatic PCa, oligorecurrent PCa, and oligoprogressive PCa. A cut off of three to five metastatic lesions is most often used in these settings. Data from retrospective studies, treating over 1000 patients in total, have been reported. The median progression-free survival ranges between 1 and 3 years, but is influenced by a heterogeneous use of androgen deprivation therapy. For lymph node metastases, a propensity scored matched analysis suggests that cancer specific and overall survival is improved with MDT over standard of care. MDT treatment regimens vary with different radiotherapy techniques, doses, and volumes. Adverse events are limited to grade 1-2 and only rarely grade 3 events are reported.

Based on data from retrospective studies, progression-free survival following MDT for oligometastatic PCa is promising with few adverse events. Comparative prospective studies are under way and will shed light on the future of MDT.