Abscopal effect and interventional oncology: state of art and future perspectives

The concept of abscopal effect is currently gaining importance in modern oncology, as the link between localized irradiation and triggering of immuno-mediated systemic antitumor effects is getting clearer. An increasing number of reports documented abscopal effect mainly after external beam irradiation. Interventional radiotherapy (IR) may be used with sealed radioactive sources as brachytherapy (BT) or with unsealed radioactive sources as transarterial radioembolization (TARE). The aim of this paper is to review the existing clinical IR data and discuss the mechanisms of the abscopal effect.

A systematic research of the main bibliographic databases (PubMed, WOS, Scopus, and Google Scholar) from the earliest possible date through August 2019 was performed. The search strategy was based on the terms "abscopal effect", "interventional radiotherapy", "brachytherapy" and "TARE".

Thirteen titles were identified. Three papers met inclusion criteria and were included in the review. All of them were case reports.

Even though there are still scarce data in literature regarding the association of locoregional interventional treatments with the abscopal effect, this review demonstrates that the immunomodulatory theories, which have been widely used so far for external beam radiotherapy (EBRT), may be actually considered valid also in the contest of IR.