Evolving role of salvage reirradiation: Is global harmonization required before treatment guidelines can be developed?

Abstract

Up to 90% of patients initially treated with curative-intent radiotherapy (RT) will experience locoregional failure. Historically, reirradiation (ReRT) was offered purely with palliative intent, if considered at all, due to concerns surrounding toxicity, tolerance of normal tissues, and choice of appropriate dose schedule. With technological advancements in RT delivery, coupled with longer survival in many malignancies secondary to improvements in systemic therapy, a small subset of patients presenting with localized recurrence is increasingly being offered salvage ReRT. However, this is largely on an ad hoc basis, guided mainly by small retrospective, single-institution reports. The patient population retreated, RT modality, dose received, degree of attrition and follow-up are extremely variable. The opportunity presently exists to apply lessons learned from the harmonization of the research efforts within the bone metastases community to the salvage ReRT situation: the adoption of common endpoints, minimum features to be incorporated into clinical trial design, and methods of data analysis and reporting. The ReRT data available must be harmonized so that valid, clinically applicable conclusions can be drawn. Collaboration in the form of an international registry of prospectively collected outcomes of patients reirradiated for cure for a variety of tumour sites would further support the evolution of Radiation Oncology towards personalized medicine, and away from the current “one-dose-fits-all” approach.

Keywords: Reirradiation, Salvage, Treatment planning, Toxicity, Registry, Dose, Radiotherapy

Core tip: Given the heterogeneity of the available reirradiation evidence, an international registry would provide a foundation on which to base consensus recommendations regarding many of the outstanding questions surrounding patient selection and treatment planning. Inter-centre collaboration will be required to build a critical mass of data sufficient for robust statistical analysis; however, in order to achieve this, global harmonization is needed. Standardized nomenclature would facilitate consistent coding of treated volumes, doses, toxicity rates, and quality of life outcomes. A registry would also assist in determining the feasibility of both phase II prospective studies and meta-analysis of currently available data.