ESTRO 2025 - Abstract Book

S1424

Clinical - Lung

ESTRO 2025

Material/Methods: A total of 73 patients with LS-SCLC who had response to cCRT in our hospital from March 2010 to December 2023 were retrospectively analyzed. The treatment schedule was administered as dose escalated Twice-Daily-RT (54Gy in 30fr) or Twice-Daily-RT (45Gy in 30fr) or conventional scheme (60Gy/30fr). Patients were divided into PCI and non PCI groups based on administration of PCI. The reason of omission was patients’ treatment refusal. The MRI brain surveillance was performed to these patients. Categorical variables were compared using the Chi-squared test or Fisher’s exact test. Overall survival (OS) was calculated by using the Kaplan-Meier method, with comparisons by the log-rank test. Results: The PCI group had 38 and non-PCI group had 35 patients. The median age (63 year in PCI vs. 66-year in non-PCI group), tobacco usage and chemotherapy cycles distribution were similar in both groups. The median follow-up time was 41 vs 18 months for PCI and non-PCI group, respectively. The number of patients treated with dose escalated Twice-Daily RT was significantly higher in the non-PCI group (25 vs 33; p: 0.003). Additionally, the number of patients who received first-line immunotherapy was significantly higher in the non-PCI group (5 vs 13; p:0.01). There was no significant difference in CNS recurrence in both groups (10 in PCI vs 8 in non-PCI group; p:0.73), but median time-to-failure was significantly higher in the PCI group (28 months ve 7 months; p:0.13). Conclusion: This retrospective study indicated that PCI did not reduce the incidence of metastasis in patients with LS-SCLC but prolonged the time to metastasis. However, when interpreting this result, we would note that the use of immunotherapy and dose escalation in these groups were significantly higher in the group that did not receive PCI, and the follow-up period was shorter in the group that received PCI.

Keywords: Brain recurrence, MRI surveillance

4080

Digital Poster risk of atrial fibrillation after radiotherapy for lung cancer : should we consider pulmonary veins as an organ at risk ? Mouna Ben Rejeb, Siwar Abdessaied, Selma Ghorbel, Ghada Abdessatar, Abir Boubaker, Roua Toumi, Raja Oueslati, Ghada Bouguerra, Rihab Haddad, Awatef Hamdoun, Lilia Ghorbal, Lotfi Kochbati Radiotherapy, Abderrahman Mami Hospital, Ariana, Tunisia Purpose/Objective: Atrial fibrillation (AF) is a recognised potential adverse effect of thoracic radiotherapy (RT). Data suggested that the pathological cardiac tissue responsible for AF is commonly located in the pulmonary veins (PV). However, these vessels are not currently considered organs at risk during RT planning. The aim of this study was to assess radiation dose distribution to PV among three dimensional conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT) and to investigate the feasability of VP sparing.

Material/Methods: Thirty-one patients previously treated with 3DCRT for lung cancer were retrospectively re-planned using VMAT with VP sparing. Median prescribed dose was 58,8 Gy [44-66 Gy]. The PV were retrospectively delineated using the M. Walls’ pulmonary vein atlas.

VMAT and 3DCRT plans were compared in terms of mean (Dmean), maximum doses (Dmax), V20Gy, V30Gy, V46Gy, V55Gy and V60Gy. The Wilcoxon signed-rank test was used for statistical analysis, a p value less than 0.05 was considered statistically significant.