Combined large cell neuroendocrine carcinoma: clinical characteristics, prognosis and postoperative management

OBJECTIVES: Combined large cell neuroendocrine carcinoma (C-LCNEC) is pulmonary large cell neuroendocrine carcinoma (LCNEC) mixed with other components, such as adenocarcinoma (AD) and squamous cell carcinoma (SCC). This study aimed to describe the distinct features between C-LCNEC with different components and explore the treatment strategy. METHODS: We retrospectively collected data of 96 C-LCNEC patients who underwent surgical resection. Propensity score matching was used to balance baseline characteristics of LCNEC combined with AD (LCNEC/AD) and LCNEC combined with SCC (LCNEC/SCC). RESULTS: In our final cohort, 71 (74%) were LCNEC/AD, while 25 (26%) were LCNEC/SCC. LCNEC/AD was more likely to occur in female, younger adults, with visceral pleural invasion and with driver gene expression. However, there was no significant difference in disease-free survival and overall survival between the 2 groups (before matching: P = 0.79 and P = 0.85; after matching: P = 0.87 and P = 0.48), while adjuvant chemotherapy (P = 0.019 and P = 0.043) was an independent predictor. C-LCNEC patients of stage II or III receiving adjuvant chemotherapy had longer disease-free survival and overall survival (P = 0.054 and P = 0.025), and the benefit of etoposide-based chemotherapy was greater than the other regimens (P = 0.010 and P = 0.030). EGFR and ALK mutations were present in 28% (17/60) and 7% (4/60) of C-LCNEC patients, respectively, and they responded well to targeted therapy. CONCLUSIONS: LCNEC/AD was the most common type of C-LCNEC, and there were many differences between different combined components. Adjuvant chemotherapy, especially etoposide-based chemotherapy, was a beneficial option for resected C-LCNEC.