Citation: Lung Cancer. 2020, 139
Author: Rulach R.; Harrow S.; Fenwick J.
Abstract: Introduction: Radical re-irradiation for lung cancer is indicated for local recurrence after radical radiotherapy or the development of a new lung primary. We estimate approximately 900 patients annually in the UK may be eligible for re-irradiation. Retrospective studies have shown the expected overall survival from re-treatment is 17 months, but a grade 3 or above toxicity rate of 5-20% and a mortality rate of 3%. There is no high level evidence regarding cumulative dose constraints for thoracic re-irradiation. The aim of this project is to generate putative re-irradiation dose constraints using published data. Method(s): A literature search was conducted using MEDLINE and the Glasgow University search engine, identifying any English language studies from 01/01/1970 to 01/10/2018 which included adult humans who had two courses of radiotherapy for malignancy, where both the dose given to a given organ/tumour and the toxicity encountered were published. Animal models were excluded. Data were collected for the following organs at risk (OARs): aorta, oesophagus, spinal cord, bronchial tree, lungs, heart, skin and brachial plexus. The cumulative doses to the OARs were calculated as the equivalent dose in 2-Gray fractions (EQD2) using the alpha/beta ratios in Table 1. Result(s): 244 studies were screened and 90 papers had sufficient data for analysis. Data from 2400 patients were included. The cumulative EQD2 listed in Table 1 represents the cumulative maximum dose (Dmax) received by each OAR before toxicity was first observed. There was inadequate dose/volume information in the literature to create dose/volume constraints. Conclusion(s): These are crude estimates of the maximum cumulative doses thorax OARs can tolerate at re-irradiation. This Dmax data is relevant to serial OARs, but not useful for parallel organs. There is no data regarding cardiac re-irradiation. Further research is ongoing to model dose/volume constraints and better quantify the risk of toxicity at a given dose. Disclosure: All authors have declared no conflicts of interest. Table Presented Copyright © 2020 Elsevier B.V.
