Abstract
Large cell neuroendocrine carcinoma (LCNEC) is a rare and enigmatic tumor, characterized by neuroendocrine features and a poor prognosis similar to small cell lung cancer (SCLC). The present report details the case of a 45-year-old male with oligometastatic stage IV LCNEC who achieved clinical cure after undergoing perioperative immunochemotherapy. Despite the typical non-recommendation of surgery for stage IV cases, based on the insistence of the patient, the present study initiated three cycles of neoadjuvant therapy combining serplulimab (a programmed cell death protein 1 inhibitor) with chemotherapy, resulting in the radiological disappearance of the tumor. Pathological complete response was confirmed following resection of the primary tumor. The treatment continued with three cycles of adjuvant therapy using serplulimab and chemotherapy, followed by maintenance therapy with serplulimab alone. After 17 cycles of maintenance therapy, a positron emission tomography-computed tomography scan revealed a complete metabolic response of the metastasis, and radiological scans revealed no visible tumor or distant metastasis, indicating a clinical cure. Event-free survival has exceeded 11 months, and overall survival has exceeded 14 months. The present case highlights the efficacy of immunochemotherapy in treating advanced LCNEC.