S897
Clinical - Mixed sites & palliation
ESTRO 2026
versus low-dose radiotherapy in lung (dose threshold: above or below/equal to 66Gy) or oesophageal cancer (dose threshold: above or below/equal to 50.4Gy). Searches included MEDLINE, EMBASE, Cochrane, and ESMO databases review (through June 2025). Statistical analyses were tailored to data availability: odds ratios with random-effects pooling for oesophageal cancer studies reporting time-point survival proportions, and meta-regression with beta coefficients for lung cancer studies reporting median survival times. EQD2-based meta-regression assessed continuous dose–response. Heterogeneity was evaluated with I ² and risk of bias with Cochrane criteria. Results: Among 18,787 screened records, 11 studies met inclusion criteria for quantitative synthesis. In oesophageal cancer (n=6 studies/n=1,123 patients), higher-dose improved PFS compared with lower-dose radiotherapy (pooled OR=0.81; 95% CI 0.68–0.97; p=0.02; Figure1a). Benefits were seen at 1-year (OR=0.62; p=0.02) and 2-years (OR=0.77; p=0.05), but not at 3-years (OR=1.04, p=0.79). Restriction to randomized trials (n=4 studies/n=943 patients) removed the PFS advantage (OR=0.94; p=0.56). No OS benefit was observed across all time points (pooled OR=0.87; 95% CI 0.72–1.05; p=0.14; I ² =0%; Figure1b).
(10%). Adenocarcinoma was the most common histology (70%). Median GTV size was 1.3 cm (range, 1.0-7.4 cm). ReRT was delivered after a median 13.3 months (range: 6.0-63.4 months) from the first RT course, which was prescribed to a median 50 Gy (range: 40-70 Gy) in a median 5 fractions (range: 5-30 fractions). Median GTV reRT mean, minimum, and maximum, and doses were 58.9 Gy, 36.0 Gy, and 69.5 Gy, respectively. Median GTV reRT D95% and V120% were 51.3 Gy and 43.6%, respectively. Cumulative maximum OAR EQD2 of the stomach, duodenum, small bowel, and large bowel were 129.4 Gy3, 127.6 Gy3, 131.4 Gy3, and 79.0 Gy3, respectively. Median follow-up was 7.3 months (range, 2.8-12.4 months). No acute/late grade 3+ AEs and no statistically significant change in FACT-G scores was observed within 3 months. 1-year FFLP and 1-year OS were both 100%. Conclusion: This is the first prospective trial to evaluate ablative 5- fraction reRT for abdominal/pelvic tumors. We demonstrate early feasibility and safety with promising efficacy despite the unfavorable proximity of GI OARs to target lesions. Keywords: reirradiation Impact of radiotherapy dose escalation on survival in lung and oesophageal cancers: a PROSPERO- registered systematic review and meta-analysis Ahmed Salem 1 , Louai Alsaloumi 2 , Hebah Alderbashi 3 , Talal Twal 3 , Yousef Alsabatien 3 1 Department of Anatomy, Physiology and Biochemistry, Faculty of Medicine, The Hashemite University, Zarqa, Jordan. 2 Department of Applied Pharmaceutical Sciences and Clinical Pharmacy, Faculty of Pharmacy, Isra University, Amman, Jordan. 3 Faculty of Medicine, The Hashemite University, Zarqa, Jordan Purpose/Objective: Dose escalation in thoracic radiotherapy remains clinically debated, particularly for lung and oesophageal cancers where side-effects limit radiotherapy intensification. This meta-analysis Mini-Oral 3405 evaluated the effect of higher versus lower radiotherapy doses on overall survival (OS), progression-free survival (PFS), dose–response patterns, and adverse-events in lung and oesophageal cancers. Material/Methods: This is a PROSPERO-registered systematic review and meta-analysis. We identified studies comparing high-
EQD2 meta-regression showed no dose–response relationship for either PFS ( β =0.0097; p=0.736) or OS ( β =0.0099; p=0.774); Figure2a. In lung cancer (n=5 studies/n=1,327 patients), meta-regression analysis revealed no significant associations between radiotherapy dose and survival outcomes. For PFS, EQD2 was not a significant predictor ( β =-0.13; 95% CI: - 0.35 to 0.08; p=0.23), indicating that dose escalation was not associated with improved PFS; Figure2b Similarly, no OS benefit was demonstrated with higher radiotherapy doses ( β =-0.51; 95% CI: -1.41 to 0.39; p=0.27); Figure2c. Adverse-event reporting was inconsistent, precluding pooled analysis.
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