ESTRO 2025 - Abstract Book

S1315

Clinical - Lung

ESTRO 2025

1117

Digital Poster Association between Tumor Regression during Radiotherapy and Survival in Lung Cancer: A Systematic Review and Meta-Analysis Haiyan Peng, Fu Jin, Jianfeng Li, Xiaojiao Wang, Xuechun Wang Department of Radiation Oncology, Chongqing University Cancer Hospital, Chongqing, China Purpose/Objective: To investigate the relationship between tumor regression during radiotherapy and survival outcomes in lung cancer patients, using a systematic review and meta-analysis. Material/Methods: Relevant studies were systematically identified from databases including PubMed, Web of Science, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov, covering publications from 1975 to October 2023. The search utilized MeSH terms such as Lung Neoplasms, radiotherapy, tumor regression, survival, and survival analysis. Studies were included if they reported adequate prognostic factors and adjusted for confounders in their analysis. Hazard ratios (HRs) for overall survival (OS) were extracted and converted to regression coefficients (β) to model the continuous relationship with tumor regression volume (TRV) during radiotherapy. Both fixed-effects and random-effects models were applied, with inverse variance (1/SE²) used to weight individual studies. Publication bias was assessed via the trim-and-fill method. Results: Thirty-two cohort studies involving 3543 patients were included in the meta-analysis. Patients were stratified into high and low TRV groups based on predefined cut-off values. Six studies focused on OS following radiotherapy, while 26 examined OS after chemoradiotherapy. The meta-analysis showed that an increase in TRV was significantly associated with improved OS after chemoradiotherapy (HR, 0.79; 95% CI, 0.64-0.98, p < 0.01; I² = 75%). Subgroup analyses by age and stage revealed no significant heterogeneity for patients aged ≤60 (HR, 0.61; 95% CI, 0.50–0.75; I² = 32%) and those with Stage ≥III (HR, 0.66; 95% CI, 0.51–0.87; I² = 23%). These findings remained robust after adjusting for publication bias and excluding studies with the largest weight. Patients with high tumor regression had a 21% lower risk of death and a 29% lower risk of disease progression compared to those with low tumor regression during chemoradiotherapy. Furthermore, a 20% reduction in tumor volume was associated with an 18% increase in relative OS rate. These results were consistent across progression-free survival (PFS) and cancer-specific survival analyses, showing a 20% increase in relative PFS rate. Conclusion: This meta-analysis demonstrates that greater tumor regression during radiotherapy is associated with improved survival outcomes in lung cancer patients. High TRV correlates with reduced mortality and disease progression risks, suggesting tumor regression as a valuable prognostic indicator in the treatment of lung cancer.

Keywords: tumor regression, survival outcomes