A clinicopathological study of peripheral, small-sized high-grade neuroendocrine tumours of the lung: differences between small-cell lung carcinoma and large-cell neuroendocrine carcinoma

Small-cell lung carcinoma (SCLC) and large-cell neuroendocrine carcinoma (LCNEC) are categorized as high-grade neuroendocrine tumours because of their poor prognosis compared with those of other neuroendocrine tumours of the lung. There have been no clinicopathological studies focusing on small-sized high-grade neuroendocrine tumours. We analysed clinicopathological features of peripheral, small-sized high-grade neuroendocrine tumours of the lung retrospectively. A total of 28 patients with peripheral, small-sized tumours (maximum diameter of 3.0 cm) of SCLC and LCNEC underwent surgical resection in our hospital and were enrolled in this study. Of 28 tumours, 18 were SCLC and 10 were LCNEC. In terms of serum tumour marker levels, carcinoembryonic antigen was elevated in 50% of both types of tumour, and progastrin-releasing peptide was elevated in 28% of SCLC and 10% of LCNEC. With regard to preoperative diagnosis, only seven SCLC cases were correctly diagnosed as SCLC, but no LCNEC case was correctly diagnosed before surgery. Lymphatic involvement was significantly more frequent in SCLC than in LCNEC (P = 0.013). Although adjuvant chemotherapy was carried out more frequently in the patients with SCLC than LCNEC, the recurrence rate after the standard surgery was significantly higher in the patients with SCLC than LCNEC (P = 0.0037). There was a significant difference between SCLC and LCNEC in terms of overall survival in clinical-stage IA small-sized tumours (P = 0.029). In peripheral, small-sized high-grade neuroendocrine tumours, there are several clinicopathological differences between SCLC and LCNEC. This study suggested that the prognosis of patients with LCNEC tended to be better than for those with SCLC in small-sized tumours.