Effect of tobacco use on response to immunotherapy in patients with cancer.

e14537 Background: Evidence from existing literature suggests that it remains unclear if tobacco usage affects the efficacy of immune checkpoint inhibitors (ICI). This research aims to evaluate the connection between smoking and the effectiveness of immune checkpoint inhibitor (ICI) therapy in specific cancer types treated at our institution. Methods: This is a retrospective cohort study where cancer patients >18 years old who received immunotherapy from 2017 to 2023 were identified through our center’s Cancer Registry. This study focuses on three major cancer types: lung, head and neck, and melanoma. 458 patients with their demographics, staging, duration of treatment and last contact have been assessed. SAS 9.4 was used for analysis with Chi-square/Fisher’s Exact testing, Student’s T-test, life tests and the Cox proportional hazards model to discern the effects of tobacco use and overall survival. Results: Among 458 patients, 48 (10.48%) are never-smokers, and 410 (89.52%) are smokers (current or former). Overall, 211 (46.06%) have stage 0-IIIA, while 247 (53.93%) have IIIB-IVB tumors. The mean age is 66.08 years. Additionally, 330 patients (72.05%) received chemotherapy as part of their treatment regimen in addition to immunotherapy. Non-tobacco users exhibit a higher survival probability compared to tobacco users. At five years, non-tobacco users showed a survival rate of 41%, whereas tobacco users had a survival rate of 28% (p=0.01) and hazard ratio HR of 1.55 (95% confidence interval, 1.00–2.39). The median survival for all patients is 40 months among non-tobacco users and 19 months among tobacco users. Moreover, there is no difference in the survival rates between current and former smokers. Conclusions: The study demonstrates that immunotherapy has better outcomes and increases survival probability in non-tobacco users. Also, there is no difference in survival between current or former tobacco users. However, these findings warrant future prospective studies.