Clinical characteristics and survival analysis of non-smoking small cell lung cancer

Despite the general belief that smoking is the primary cause of small cell lung cancer (SCLC), a significant number of SCLC cases do not have a history of smoking. Research on the clinical characteristics and prognosis of non-smoking SCLC is essential. This study aimed to analysis of the clinical characteristics, prognosis, and the impact of treatment changes on survival of patients with non-smoking SCLC.

We conducted a retrospective analysis of non-smoking SCLC at a single cancer center from January 1, 2013, to March 31, 2025. Descriptive statistics were used to summarize the baseline characteristics of the study population. The Kaplan-Meier method was used for survival analysis. Differences in survival distributions between these groups were compared using the log-rank test.

A total of 1,607 patients were non-smokers, with a higher proportion of females (58.6%). The median age was 59 years. Among them, 980 patients had limited-stage SCLC (LS-SCLC). For LS-SCLC, the median overall survival (OS) was 34.27 months [95% confidence interval (CI): 30.17-38.37 months], while it was 18.37 months (95% CI: 16.76-19.78 months) for extensive-stage SCLC (ES-SCLC). The OS of LS-SCLC patients between the two periods varied significantly according to a temporal trend analysis, stratified by 2019 (P<0.001). The median OS of patients with ES-SCLC diagnosed after 2019 was significantly improved compared to that of patients diagnosed before 2019 (P=0.004).

A distinct subgroup of SCLC with unique characteristics is non-smoking SCLC. The prognosis for patients with non-smoking SCLC is also improving due to treatment advancements.