Prognostic factors, and survival difference in gastrointestinal extrapulmonary small cell carcinoma using SEER database.

Abstract

e16170 Background: Gastrointestinal extrapulmonary small cell carcinoma (GI EPSCCa) is a rare and aggressive tumor. Current treatment guidelines are extrapolated from small cell lung cancer. Factors affecting survival, and the role of primary tumor location are currently unknown. Methods: Using the SEER database to identify patients diagnosed from 2000 to 2018, we used Cox proportional hazard models to assess prognostic factors based on primary tumor location. Results: Of the 1,687 patients included in the analysis, 79.7% were White and 56.9% male. Distribution of the primary location were 31.5% colorectal (CRC), 22.1% Esophagus, 20.6% pancreas, 13.3% hepatobiliary (HB), 10.6% stomach, and 1.8% small intestine (SI). Patients ≥65 years were more likely to have esophago-gastric, SI, HB and pancreatic EPSCCa (P<0.001). Males were more likely to have esophago-gastric, CRC and pancreatic EPSCCa (P<0.001). While Blacks were more likely to have esophago-gastric and SI EPSCCa, Whites were more likely to have CRC, HB and pancreas EPSCCa (P=0.012). There were no racial differences in overall survival (OS) for GI EPSCCa. Male gender (adjusted Hazard Ratio(aHR)=1.12, 95%CI:1.00-1.24, P=0.042), and age ≥65 (aHR)=1.21, 95%CI:1.09-1.35, P=0.001) were associated with inferior OS. Advanced stage at presentation, or not receiving radiation therapy/ chemotherapy were also associated with worse OS. Surgical intervention, and treatment period after 2006 were associated with superior OS (Table) Regarding GI site, HB EPSCCa was associated with inferior OS compared with esophageal EPSCCa (aHR)=1.21, 95%CI:1.00-1.46, P=0.048). SI EPSCCa had a trend toward improved OS (compared to esophageal EPSCCa) (P= 0.237). Conclusions: Chemotherapy, surgery, radiation therapy, female gender, younger age were associated with superior OS for GI EPSCCa, while advanced stage, HB sites (compared to esophageal EPSCCa) were associated with poorer outcome. OS for GI EPSCCa has improved over time. Prospective studies are needed to guide therapy for this aggressive tumor. [Table: see text]