ESTRO 2024 - Abstract Book

S1639

Clinical - Lung

ESTRO 2024

1011

Digital Poster

Thoracic radiotherapy and PCI in extensive stage small cell lung cancer following chemoimmunotherapy

Lily Sibley 1 , Clara Chan 2 , Isabella Fornacon-Wood 3 , Danya Abdulwahid 2 , Claire Barker 2 , Neil Bayman 2 , Fiona Blackhall 3,4 , Raffaele Califano 4,3 , Joanna Coote 2 , Laura Cove-Smith 4 , Fabio Gomes 4 , Emma Halkyard 4 , Margaret Harris 2 , Sarah Hughes 4 , Jenny King 2 , Colin Lindsay 3,4 , Laura Pemberton 2 , Hamid Sheikh 2 , Yvonne Summers 4 , Paul Taylor 4 , David Woolf 2 , Corinne Faivre-Finn 3,2 1 University of Manchester, School of Medicine, Manchester, United Kingdom. 2 The Christie NHS Foundation Trust, Department of Clinical Oncology, Manchester, United Kingdom. 3 University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom. 4 The Christie NHS Foundation Trust, Department of Medical Oncology, Manchester, United Kingdom

Purpose/Objective:

Extensive stage small cell lung cancer (ES-SCLC) is an aggressive cancer associated with poor outcomes. The practice-changing Impower133 trial demonstrated that the addition of immunotherapy to chemotherapy in PS 0-1 patients improved overall survival 1 . However, only a minority of patients included in Impower133 received prophylactic cranial irradiation (PCI) and no patients received thoracic radiotherapy (TRT). In the era of chemoimmunotherapy, there is uncertainty amongst clinicians regarding the role of PCI and/or TRT. We aimed to investigate referral patterns for PCI and TRT, explore decision making, and ascertain patient outcomes for ES-SCLC patients treated with chemoimmunotherapy.

Material/Methods:

This was a single centre study. Patients with ES-SCLC who received chemoimmunotherapy from 01/01/2020 to 09/03/2023 were retrospectively identified, and patients not eligible for PCI or TRT based on international guidelines were then excluded. All patients received Carboplatin (AUC 5 D1), Etoposide (100mg/m2 D1, 200mg/m2 D2-3) and Atezolizumab (1200mg D1). Data was gathered from a structured form filled in prospectively in the patient electronic record, including baseline demographics including performance status (PS) pre and post chemotherapy, proportion of eligible patients referred for and who eventually received PCI or TRT, toxicity of treatment (according to CTCAE v 5.0), patterns of progression, progression free and overall survival. Qualitative data on the decision-making process not to refer or deliver PCI/TRT and inter-clinician variability were also collected. Chi-squared tests were used to ascertain the statistical significance of the differences between groups. Kaplan Meier curves were generated for progression free and overall survival using R software and the log-rank test used to compare groups.

Results: