DLL3 and large cell neuroendocrine carcinoma: A multivariate analysis for RFS revealed that adjuvant chemotherapy was a significant independent prognostic factor among patients with DLL3 expression‐negative LCNEC (HR: 0.05, 95% CI: 0.01–0.41, P < 0.01), although it was not a significant independent prognostic factor among patients with DLL3 expression‐positive LCNEC (HR: 0.73, 95% CI: 0.23–2.27, P = 0.58) (Table 4).