Distinct clinicopathologic features, genomic characteristics and survival of central and peripheral pulmonary large cell neuroendocrine carcinoma: From different origin cells?

Background: Pulmonary large cell neuroendocrine carcinoma (LCNEC) represents a rare entity in lung cancer with dismal prognosis. In the present study, we investigated whether there are significant differences between central and peripheral tumors of LCNEC, in terms of clinicopathologic features, genomic profiles, and survival. Methods and materials: A total of 126 cases of LCNEC were included. The tumors with invasion of the segmental and/or lobar bronchus were classified as central LCNEC and those without as peripheral LCNEC. EGFR/BRAF/Kras mutations and ALK/ROS1 translocations were detected. Overall survival (OS) was evaluated by the Kaplan-Meier plots. Results: The majority of LCNEC proved to be of the peripheral type (64.3%, 81/126). Central tumors were associated with smoking habit (p = 0.047), higher TNM-stage (p = 0.014) and larger tumor size (p < 0.001). Expression of neuroendocrine markers (CD56, CGA, and SYN) was not significantly different by tumor location but central tumors had higher serum levels of NSE (p = 0.004). Peripheral tumors had a higher incidence of EGFR mutations (18.8% vs. 0%, p = 0.023). ROS1 translocation was detected in 1 patient with peripheral LCNEC. RB1 protein was more frequently expressed in peripheral tumor than central tumor. The median OS was 3.71 years in the entire cohort. Peripheral tumors had better survival compared with central tumors (median OS: 4.04 vs. 1.51 years, p < 0.001). Multivariate analyses demonstrated tumor location (hazard ratio [HR], 6.07, 95% confidence interval [CI], 1.57-23.44, p = 0.009), resection status (HR, 6.58, 95% CI, 1.92-22.51, p = 0.003) and EGFR mutational status (HR, 0.18, 95% CI, 0.04-0.75, p = 0.018) were independent prognostic factors for OS. Conclusion: Primary tumor location of LCNEC, divided into central and peripheral type, has distinct clinicopathologic features, genomic characteristics and survival. These differences are likely due to differences in the origin cells and pathogenesis of these tumors.