2457 - Impact of Smoking Status on Survival and Radiation-Induced Toxicity in Lung Cancer Patients Receiving Radiotherapy: A Retrospective Cohort Study
Presenter(s)
J. S. Pavão1, M. L. T. Bento1, T. R. Dias1, R. A. B. Aguiar1, L. B. Assuncao1, G. L. F. Cunha1, L. Oliveira2, R. Ferrari3, G. Barbosa4, E. Fuks5, P. Canary6, C. Almeida7, J. Melo8, and D. Przybysz6; 11. RadioSerra Radiation Therapy 2. Petropolis Medical School - FMP, Petrópolis, Brazil, 21. RadioSerra Radiation Therapy, Petrópolis, Brazil, 3RadioSerra, Petrópolis, Rio de Jan, Brazil, 4Radioserra Radiation Therapy, Petrópolis, Brazil, 5Radioserra Radiation Therapy, Petrópolis, RJ, Brazil, 6RadioSerra Radiation Therapy, Sao Paulo, Sao Paulo, Brazil, 7Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil, 81.CTO e 2.RadioSerra Radiation Therapy, Petrópolis, Brazil
Purpose/Objective(s): Although smoking is well-established as a significant risk factor for lung cancer, its specific impact on radiotherapy efficacy and toxicity remains insufficiently characterized. This study aimed to evaluate the association between smoking status and overall survival (OS), radiation-induced pulmonary toxicity, and lung dosimetric parameters in lung cancer patients receiving radiotherapy, to inform personalized treatment approaches.
Materials/Methods: We retrospectively analyzed 207 lung cancer patients treated with radiotherapy between 2020 and 2024. Patients were stratified by smoking status into active smokers (11%), ex-smokers (50%), and non-smokers (39%). Radiotherapy was administered with curative or palliative intent. Dosimetric parameters including lung volumes receiving =5% (V5%) and =20% (V20%) prescribed dose, as well as mean lung dose (MLD), were evaluated. Primary endpoints were OS and incidence of grade =2 radiation pneumonitis. OS was assessed using Kaplan-Meier survival analyses and Cox proportional hazards regression models; pulmonary toxicity was evaluated via chi-square testing.
Results: Active smokers had significantly reduced OS compared to non-smokers (median OS: 12 vs. 20 months, p=0.004). Ex-smokers demonstrated intermediate survival outcomes, indicating residual harm from previous tobacco exposure (2-year OS range: 68.1%–78.9%). Grade =2 radiation pneumonitis was significantly more frequent in active smokers than non-smokers (22% vs. 12%, p=0.03). Active smokers also exhibited higher rates of pulmonary fibrosis. Dosimetric analysis revealed significantly higher lung V20% among smokers, reflecting increased lung exposure. Differences in MLD and V5% did not reach statistical significance. The findings highlight active smoking’s detrimental effects on survival and radiotherapy-associated pulmonary toxicity. Higher V20% values observed in active smokers are likely to contribute to increased pulmonary toxicity, underscoring the necessity for smoking cessation programs integrated within clinical care. Personalized adaptive radiotherapy planning could potentially reduce toxicity in smoking populations. The biological mechanisms driving these effects, possibly involving tumor hypoxia and inflammatory responses, warrant further exploration.
Conclusion: Active smoking significantly reduces survival and increases pulmonary toxicity in lung cancer patients undergoing radiotherapy. Smoking cessation programs and tailored treatment strategies are essential to improve outcomes for smokers receiving radiotherapy.