Clinical Analysis of Extrapulmonary Neuroendocrine Carcinoma: A Retrospective and Single Institution Experience

Introduction: Extrapulmonary neuroendocrine carcinoma (EPNEC) is a clinicopathological entity distinct from neuroendocrine carcinoma of the lung. Here, we reviewed the clinical features, treatment modalities, and prognosis of EPNEC patients in a single-institution series. Methods: We retrospectively reviewed the medical records of EPNEC patients and examined the clinical profiles and treatment outcomes at our hospital between 2013 and 2021. Results: Thirty-one EPNEC patients (21 men and 10 women) with a median age of 65 years were included. The primary sites were as follows: stomach (n = 7); rectum and bladder (n = 3 each); prostate, esophagus, cervix, and pancreas (n = 2 each); maxillary sinus, parotid gland, gallbladder, anal canal, larynx, uterine body, ovary, appendix, anterior mediastinum, and unknown primary lesion (n = 1 each). Thirteen patients had locally advanced stage and 18 cases had distant metastases. Chemotherapy using platinum-combined CPT-11 or VP-16 was mainly performed. Various therapeutic modalities were used, especially in locally advanced cases. Ten patients underwent surgery, including initial surgery in 5 and conversion in 5 after chemotherapy. The response rate to initial chemotherapy was 56.5%, and the median overall survival in all patients was 12.8 (95% CI: 9.6–34.5) months. Survival was significantly longer in patients with locally advanced stage (80.3 months) and receiving surgery (not reached) than in those with metastatic disease (9.9 months) and without surgery (9.6 months). Conclusion: EPNEC occurs in various organs and has poor prognosis. Long-term survival may be possible with surgical resection in cases with early-stage disease or tumor shrinkage due to chemotherapy.