Small Cell Carcinoma as an Independent Prognostic Factor for Cervical Cancer Patients: A Population-Based Analysis

Abstract Background: Small cell carcinoma (SmCC) of cervix was a rare neoplasm with little recognition. Population-based study describing difference in characteristics and outcomes between SmCC and squamous cell carcinoma (SCC), usual type, was limited. Here, we used the Surveillance, Epidemiology, and End Results (SEER) database to compare SmCC with SCC and investigated the prognostic values of the clinicopathological characteristics and survival outcomes in SmCC of cervix.Methods: Patients diagnosed with cervical SmCC and SCC in SEER database from 2004-2015 were enrolled in analysis. Propensity-score matching analysis (PSM) was used to balance baseline characteristics between patients who were cervical SmCC and those who were cervical SCC. Cox regression models and Kaplan-Meier methods were conducted to analyze survival data before and after PSM. Stratified analyses were performed to investigate the risk of mortality at different stage. Results: In total, 25345 patients including 287 cervical SmCC patients and 25058 cervical SCC patients were enrolled our analysis. Both histological subtypes were more common in unmarried women and in white populations. Compared with cervical SCC patients, cervical SmCC patients showed a higher rate of larger tumor size (tumor size ≥4 cm, 33.8% vs 51.9%, P<0.001), higher grade disease (grade III-IV, 32.2% vs 58.9%, P<0.001), regional lymph node involvement (22.5% vs 49.5%, P<0.001) and distant metastasis (10.3% vs 32.4%, P<0.001). Before PSM, multivariate regression model revealed that SmCC histology (P<0.001) and advanced FIGO stages (P<0.001) were principal prognostic factors of poor survival for cervical patients. After PSM, 1060 patients in SCC group were 4:1 matched with 278 patients in SmCC group. Multivariate regression model in PSM cohort showed histology and FIGO stage were crucial prognostic factors for survival. Kaplan-Meier survival curves clearly showed that cervical SmCC patients had worse survival than that of patients with SCC in all stages, stage I-II, III, IV before and after PSM analysis.Conclusion: Compared to patients with cervical SCC, those with cervical SmCC showed a worse survival before and after adjustment baseline characteristic in all stages. SmCC was an independent poor prognostic factor in cervical cancer patients.