Clinical characteristics and survival of extrapulmonary small cell carcinoma in 11 different primary tumor sites in the United States, 1975-2016.

OBJECTIVE: Few studies have investigated extrapulmonary small cell carcinoma (EPSCC) in a systematic way. This study is to analyze EPSCC in 11 tumor sites from different aspects in the United States (1975-2016).

METHODS: In total 4397 patients diagnosed with EPSCC in 11 primary tumor locations were selected from the Surveillance, Epidemiology and End Results (SEER) database. The incidence of EPSCC in the last decade, and the 1, 3 and 5 year survival rates of each tumor site were also roughly calculated. Prognostic factors of EPSCC were investigated by Cox regression analysis.

RESULTS: Statistically, the incidence of EPSCC was on the rise over the past 30 years. Of its 11 primary tumor sites, bladder was the most frequently affected while the stomach and kidney were rarely affected. Males were more susceptible to EPSCC than females. Married patients were more commonly afflicted by EPSCC, but had longer survival. Cases were most intensive in California and an increased trend had been observed. The 5 year overall survival (OS) rate ranged from 2.0% to 42.5% in patients with EPSCC in 11 tumor sites ( p  < .001). The OS was better for EPSCC in the breast and cervix. However, tumor sites in the colon, esophagus, pancreas, rectum and stomach were all associated with worse survival. Characteristics and prognosis of EPSCC in different tumor sites were statistically significant ( p  < .001). Age, gender, marital status, stage, surgery, radiotherapy and chemotherapy were equally significant factors of survival of EPSCC patients ( p  < .05).

CONCLUSION: There was an increasing trend of EPSCC incidence. The survival of EPSCC in different tumor sites was significantly different. Tumor locations, age, gender, marital status, stage, surgery, radiotherapy and chemotherapy were all important factors of survival. This study has implications for EPSCC prevention and treatment.