ESTRO 2025 - Abstract Book

S1423

Clinical - Lung

ESTRO 2025

Material/Methods: Patients with stage I-III non-small cell lung cancer (NSCLC) referred for curative-intent (chemo)radiotherapy between June 2016- June 2023, and either a formal ILD diagnosis or radiological descriptors suggestive of ILD or ILA on pre radiotherapy CT imaging reports were included. Specialist ILD radiologists reviewed the CT imaging and classified patients into four groups: ILD, possible ILD, ILA, or no conclusive features. Data were collected on demographics, lung function tests, (chemo)radiotherapy treatment, dosimetry, gender-age-physiology (GAP) score, toxicity (CTCAE V5.0) and survival (overall (OS) and progression-free survival (PFS). Statistical analyses included Kaplan-Meier survival curves with log-rank tests for survival comparisons and fisher’s exact test for categorical data. Results: 170 patients were identified.(Table 1) Median follow up was 32.5 months. Radiology review classified patients as ILD/possible ILD (n=53), ILA (n=53) or no features (n=57).(Table 2) The median OS for patients with ILD/possible ILD and ILA was 13.5 months(95% CI=9.4-17.0 months), and PFS was 9.59 months(95% CI=7.7-13.2). There was a significant difference in OS (p=0.01) between those with ILD/possible ILD vs ILA vs no features (9.59, 14.7 and 22.5 months, respectively). No difference in OS (p=0.89) was identified according to GAP stage score 1-3. There was a significant difference (p=0.04) in PFS between those with ILD/possible ILD, vs ILA vs no features (9.6, 12.8 and 13.1 months). Grade ≥three toxicity occurred in 18.8%(n=10) of patients with ILD/possible ILD, 11.3%(n=6) in patients with ILA, and 5.2%(n=3) in patients with no features (p=0.09). Grade five pneumonitis occurred in 13.2%(7/53) patients with ILD/possible ILD, 5.6%(3/53) patients with ILA and no events occurred in those without features of ILD or ILA (p=0.008). https://nhs my.sharepoint.com/:w:/r/personal/sarah_bowenjones_nhs_net/Documents/Desktop/Table%201+2.docx?d=wb97d4c a8acff4427a8e313b326c12d05&csf=1&web=1&e=Yyxboc Conclusion: NSCLC patients with baseline ILD or ILA features are associated with significantly worse outcomes following radiotherapy. ILD is associated with a significantly higher risk of fatal lung toxicity. This study adds valuable insights to the limited evidence for this rare patient group. Further studies are needed to develop prognostic tools and guidelines that support joint decision-making. Digital Poster Influence of Prophylactic Cranial Irradiation in the First-Line Treatment of Limited-Stage Small Cell Lung Cancer (LS-SCLC) Sukran Senyurek 1 , Merve Duman 1 , Sena Birsen Guclu 2 , Nulifer Kilic Durankus 1 , Duygu Sezen 1 , Saliha Ezgi Oymak 3 , Nil Molinas Mandel 4 , Fatih Selcukbiricik 4 , Yasemin Bolukbasi 1 , Ugur Selek 1 1 Department of Radiation Oncology, Koc University, Istanbul, Turkey. 2 School of Medicine, Koc University, Istanbul, Turkey. 3 Department of Radiation Oncology, Amerikan Hospital, Istanbul, Turkey. 4 Department of Medical Oncology, Koc University, Istanbul, Turkey Purpose/Objective: Concurrent chemoradiation (cCRT) followed by prophylactic cranial irradiation (PCI) has remained the standard treatment for LS- SCLC. The survival advantage of PCI is based on data that do not reflect the new era of immunotherapy and MRI. The underlying reason for its benefit in this patient group is still a matter of debate. In our study, we aimed to investigate the incidence of brain metastases and overall survival among patient groups treated with and without PCI. Keywords: NSCLC, radiotherapy, interstitial lung disease 4058