ImportanceProtracted wars, which disproportionately affect low-resource countries, exacerbate the challenges faced by cancer care systems, with lung cancer being the most affected as the most fatal oncological condition.ObjectiveTo characterize the presentation and survival of patients with lung cancer during the decade-long Syrian war.Design, Setting, and ParticipantsThis cohort study included patients at a large oncology center in Syria during the first 8 years of the Syrian armed conflict (2011-2018). All patients with a new diagnosis of lung cancer were included. Variables investigated included histological subtypes, TNM classification (tumor, lymph nodes, and metastasis), and staging at diagnosis as well as the yearly follow-ups up to 5 years after presentation.ExposureThe Syrian war divided the country into temporary regions with different political influences and heterogeneously impacted health care accessibility among these regions.Main Outcomes and MeasuresChange in prevalence of advanced lung cancer cases at presentation; change in overall survival odds.ResultsThe study included 5160 patients from all Syrian governorates (mean [SD] age, 59.6 [10.8] years; 4399 men [85.3%]). New diagnoses sharply declined during the first 3 years of the war, with partial recovery afterward. Regardless of their tempo-geographical regions, 60% to 80% of the yearly diagnoses presented with metastases. The 1-year and 5-year survival rates were 13.1% (423 of 3238 patients with follow-up results) and 0.1% (2 of 1853 patients), respectively. Patients who presented from regions more involved in the armed conflicts showed poorer survival rates with odds ranging between 0.51 (95% CI, 0.44-0.59) and 0.61 (95% CI, 0.49-0.74) across follow-ups for up to 2 years in comparison with patients presenting from safer regions. War-related health care inaccessibility explained a greater percentage of the variability in survival (Nagelkerke R2 = 7.5%; P < .001) than both patients’ age and the stage of the disease combined (Nagelkerke R2 = 3.9%; P < .001).Conclusions and RelevanceThe Syrian war has been associated with a marked decline in the management of patients with lung cancer, with limited access to specialized care, delayed diagnoses, and substantial decrease in survival rates correlating with the intensity of armed conflict in the respective regions. The profound repercussions of the prolonged armed conflict on patients with lung cancer in Syria necessitates urgent comprehensive strategies to improve the accessibility and quality of health care services, especially in conflict-ridden zones.