RT Journal Article SR Electronic T1 Treatment complication rates in continued smokers vs quitters after a diagnosis of lung cancer: a cohort study JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 4383 DO 10.1183/13993003.congress-2020.4383 VO 56 IS suppl 64 A1 Kirsty Lanyon A1 Rachel Gemine A1 Gareth Davies A1 Keir Lewis YR 2020 UL http://erj.ersjournals.com/content/56/suppl_64/4383.abstract AB Introduction: We have recently shown that quitting smoking AFTER a diagnosis of lung cancer is associated with a reduction in mortality by 17% at 1 year(1). Our multi-site study (NCT01192256) now reports treatment complication rates in Continued Smokers versus Quitters.Methods: Prospective, observational cohort study of 1134 UK patients with newly diagnosed non-small cell lung cancer (NSCLC). We recorded self-reported smoking status, validated with eCO(ppm) readings, at baseline and at each follow-up visit until death for up to 2 years.Treatment complications were noted by free text, if reported by the patient (e.g. diarrhoea, vomiting) or by the clinical team (e.g post-op wound infection, chemotherapy induced neutropenia, radiation pneumonitis etc). They were reviewed by a study clinician blinded to smoking status but were not graded according to severity. Data was recorded on study case report forms and confirmed from hospital databases. Missing data was removed and analysed with STATA.Results: 290 (25.6%) were smokers at baseline and 84 (29%) of these quit .At 1month, Quitters had fewer treatment complications than those who continued to smoke (p=0.03). At 6months (p=0.76) & 12months (p=1.00) there were no differences in complication rates between quitters and continued smokers.Conclusions: Quitting smoking after a diagnosis is associated with fewer complications at month 1. We are following outcomes with larger numbers and grouping treatment-related-complications into ‘mild, ‘moderate’ or ‘severe’ according to standard definitions as well as noting whether these complications necessitated treatment delays or treatment changes.1. Lung Cancer, 2019, Vol.129, p.1FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 4383.This abstract was presented at the 2020 ERS International Congress, in session “Respiratory viruses in the "pre COVID-19" era”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).