Oligometastatic Prostate Cancer: Definition and Treatment Considerations: A Review of the Literature

Background: Oligometastatic disease state is a recent concept of metastatic cancer defined as an intermediate of spread between localized and widely spread metastases. Oligometastatic prostate cancer (PCa) is being diagnosed with a greater frequency during the last decade. Multiple modalities of management of oligometastatic PCa are proposed from targeting all sites of metastases to the treatment of the primary. Objective: To review the literature regarding management of oligometastatic PCa. Method: PubMed and ScienceDirect electronic databases were queried for English and French language from 2014 to 2021. Keywords use included "cancer de prostate, oligométastases, oligometastasis and prostate cancer". Preclinical, prospective and retrospective studies were included. Result & discussion: There were rare published randomized controlled trials evaluating the treatment of oligometastatic PCa. Prospective and retrospective data suggest benefit of primary tumor treatment and Metastasis-directed therapy (MDT), especially using stereotactic body radiotherapy (SBRT). Oligometastatic PCa was defined by number of metastatic lesions clinically evident or radiographically detected (3 to 5). Treatment of the primary (radical prostatectomy or radiotherapy) was associated to a better local control, cancer specific survival, and longer median time to castration resistant PCa. MDT using SBRT has improved distant progression-free survival (DPFS), local progression-free survival (LPFS) in many studies. Conclusions: Available data suggest that local therapies such as prostatectomy and radiotherapy can be performed safely and might prevent the need for future palliative treatments. Similarly, MDT such as SBRT carry a low risk of toxic effects and provides excellent local control. Further trials are necessary and should aim to report outcomes in a consistent and systematic manner.