Impact of adjuvant chemotherapy on the overall survival of patients with resectable bulky small cell neuroendocrine cervical cancer: a JSGO-JSOG joint study

OBJECTIVE: The aim of this study was to review the clinicopathological characteristics of small cell neuroendocrine cervical cancer (SCNEC) and to identify the optimal treatment. METHODS: The Japanese Society of Gynecologic Oncology conducted a retrospective cohort study of SCNECs enrolled in the Gynecological Tumor Registry of the Japan Society of Obstetrics and Gynecology between 2004 and 2015. All cases were modified and unified by International Federation of Gynecology and Obstetrics 2008 (Union for International Cancer Control 7th edition). RESULTS: There were 822 registered patients diagnosed with SCNEC from 2004 to 2015 which comprised 1.1% (822/73,698) of all uterine cervical cancer cases. Rates of lymph-node and distant metastasis were significantly higher in T1b2 (38.9% and 13.7%, respectively) than T1b1 (14.2% and 4.4%, respectively) (p<0.01). In IB2 and T1bN1M0 SCNEC, the 5-year survival rate with surgery followed by chemotherapy was significantly higher than that with surgery followed by radiation therapy/concurrent chemoradiation therapy (p<0.01). CONCLUSION: SNCEC tumors >4 cm in size had greater rates of lymph-node and distant metastasis when compared with tumors ≤4 cm. Adjuvant chemotherapy, rather than radiotherapy, may improve prognosis after surgery in T1bN1M0 SCNEC.