Clinical Behavior of Combined Versus Pure High-Grade Neuroendocrine Carcinoma

The aim of this study was to investigate and compare the clinical behaviors of combined and pure high-grade neuroendocrine carcinoma (large-cell neuroendocrine carcinoma [LCNEC] and small-cell lung carcinoma [SCLC]).

Data of 132 patients who underwent complete resection for combined or pure high-grade neuroendocrine carcinoma (combined group, 67; pure group, 65) between January 2001 and December 2015 were retrospectively reviewed. The clinicopathological features were analyzed and compared, and the prognoses were assessed by performing the Kaplan-Meier method and Cox regression analysis.

The combined and pure groups had nearly equivalent clinicopathological characteristics, specifically, older males with smoking history, almost the same percentage of pleural/lymphatic/vascular invasion, and nearly the same recurrence rates and relapse patterns. The combined group had prognosis equivalent to that of the pure group (5-year overall survival [OS] rates: 61.8% vs. 52.2%, respectively; P = .82 and 5-year recurrence-free survival [RFS] rates: 42.4% vs. 43.9%, respectively; P = .96), and this trend was identified in sub-analyses only for patients with LCNEC, SCLC, and the same pathological stage. Multivariable Cox regression analysis in patients with high-grade neuroendocrine carcinoma revealed that vascular invasion and pathological stage were independent prognostic factors for OS; more importantly, combined and pure histologies were proven to have nearly equivalent associations with prognosis (hazard ratio, 0.96; 95% confidence interval, 0.22to 1.66; P = .96).

Combined high-grade neuroendocrine carcinoma had clinical behavior equivalent to those of pure high-grade neuroendocrine carcinoma, with similar clinicopathological characteristics.