Treatment paradigms for oligometastatic pediatric cancers: a narrative review with a focus on radiotherapy approaches

There is a growing body of prospective evidence describing an oligometastatic phenotype in adults for whom local metastasis-directed therapy can improve outcomes in select patients. However, a relative paucity of data for pediatric patients with oligometastatic disease creates challenges in choosing optimal treatment. The purpose of this review is to evaluate the literature surrounding pediatric oligometastatic disease and treatment, specifically focusing on the role of radiotherapy. A review of studies ranging from 2008 to 2020 was performed. The radiotherapy techniques evaluated included conventionally fractionated radiotherapy, stereotactic body radiotherapy (SBRT), and stereotactic radiosurgery (SRS). Our search yielded 6 studies evaluating conventionally fractionated radiotherapy, 9 studies of SBRT, and 3 studies of spine SRS. Metastasis-directed therapy for treatment of pediatric oligometastasis is generally well-tolerated, is associated with favorable local control, and is shown to improve event-free survival and progression-free survival (PFS) outcomes in select pediatric patients. Pediatric patients with oligometastatic disease may benefit from aggressive local therapy to metastatic sites in conjunction with a comprehensive treatment paradigm. Retrospective data have led to promising prospective trials that will further clarify patient selection and management. Additional data are needed to elucidate long term oncologic and toxicity outcomes.