ESTRO 2024 - Abstract Book

S5054

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2024

References:

1. De Ruysscher D, Faivre-Finn C, Le Pechoux C, Peeters S, Belderbos J. High-dose re-irradiation following radical radiotherapy for non-small-cell lung cancer. Lancet Oncol 2014;15:e620-e4.

2. Rulach R, Ball D, Chua KLM, et al. An International Expert Survey on the Indications and Practice of Radical Thoracic Reirradiation for Non-Small Cell Lung Cancer. Adv Radiat Oncol 2021;6:100653.

1482

Proffered Paper

Re-irradiation in non-small cell lung cancer: overall survival longer with higher retreatment dose

Robert Rulach 1,2 , Stephen Harrow 3 , Anthony Chalmers 2 , John Fenwick 4

1 Oxford University Hospitals NHS Trust, Oncology, Oxford, United Kingdom. 2 University of Glasgow, Oncology, Glasgow, United Kingdom. 3 NHS Lothian, Oncology, Edinburgh, United Kingdom. 4 University College London, Oncology, London, United Kingdom

Purpose/Objective:

Radical thoracic re-irradiation (re-RT) is associated with long-term disease control in selected patients. 2-year overall survival (OS 2yr ) rates for re-RT range between 11-64% with conventionally fractionated radiotherapy, and 37 -79% with stereotactic ablative body radiotherapy (SABR). Several retrospective reviews have suggested that the higher the re irradiation dose, the better the OS observed 1,2 . These findings contrast with results from the RTOG 0617 study of first line chemo-radiotherapy treatment, which demonstrated worse OS in patients treated with a higher dose 3 . We aimed to develop a dose/tumour control probability model of re-irradiation for non-small cell lung cancer (NSCLC). This would allow better counselling of patients undergoing re-irradiation of the likely benefit of treatment and indicate whether gains might be achieved via dose escalation in the re-irradiation setting.

Material/Methods:

We performed a MEDLINE literature search for studies published between 01/01/1970 and 01/10/2018 that reported the initial and re-irradiation maximum dose to the PTV and the OS 2yr rate. We also collected data on the inter treatment interval and the reported tumour volume. In studies where the duration of follow up was less than 2 years, the effective number of patients (N eff ) statistically contributing to the estimate of OS 2yr was estimated using two methods depending on the data available. If the 95% confidence interval (CI) of the OS 2yr rate was reported, the effective number of patients was calculated by the following equation: