Systematic Review of Hypofractionated Radiation Therapy for the Treatment of Oesophageal Squamous Cell Carcinoma and Oesophageal Adenocarcinoma

Background and aim: There has been limited progress made in improving the suboptimal outcomes delivered by conventionally fractionated radiotherapy (RT) for oesophageal adenocarcinoma (OAC) and squamous cell carcinoma (OSCC). A greater biological effect may be achieved using hypofractionated RT (HFRT), though the toxicity, tolerability and efficacy of this approach in OAC and OSCC is uncertain. Methods: A systematic literature review was carried out in accordance with Preferred Reporting Items for Systematic Reviews guidance. Medline, EMBASE, PubMed, Cochrane, CINAHL, Scopus and Web of Science databases were searched for terms relating to HFRT (>2.4Gy per fraction) for OAC or OSCC. All relevant clinical studies published between January 2000 and April 2023 were included. Study quality was assessed using predefined criteria. Results: Ninety-six studies were screened and 20 subsequently included, together incorporating 1208 patients. Fourteen studies focussed on neoadjuvant or definitive treatment. These were predominantly retrospective (n = 10, 71%) though two (n = 2, 14%) early phase trials were identified. Most focussed on OSCC (n = 7, 47%) or mixed OSCC/OAC (n = 6, 43%) populations. Four (28.6%) included a conventionally fractionated chemoradiotherapy (CRT) comparator, against which median overall (mOS) and progression free survival outcomes from HFRT did not differ. Reported mOS for HFRT ranged between 29-36 months at 2.5-3.125Gy per fraction (total dose 50-60Gy) for OAC and OSCC combined. Toxicity and tolerability with HFRT was comparable with conventionally fractionated CRT up to, but not exceeding, 5Gy. Three (50%) of the six palliative-intent studies were early phase trials and most (n = 4, 67%) focussed on OAC and OSCC. Response rates with HFRT in the palliative setting were 63.6-88.0%. Conclusion: These data provide evidence in OAC/OSCC for promising efficacy and an acceptable toxicity profile for moderately HFRT, alone or with concurrent chemotherapy. These data should prompt prospective, randomised comparisons of HFRT and conventionally fractionated CRT and single-modality RT schedules. Registration details: PROSPERO; CRD42023457791. (c) 2024 The Author(s). Published by Elsevier Ltd on behalf of The Royal College of Radiologists. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).