Chemotherapy in the management of olfactory neuroblastoma/esthesioneuroblastoma: An analysis of the surveillance, epidemiology, and end results (SEER) 1973-2015 database.

e17573 Background: Olfactory neuroblastoma (ON) is a malignant tumor of nasal cavity arising in sensory neuroectodermal olfactory cells. Chemotherapy (CT) has been proposed as an adjunct to primary local therapy. Here, we investigated the role of CT in primary ON treatment. Methods: SEER was searched for ON (ICD-3 9522). Inclusion criteria were (1) unique cases; (2) primary nasal cavity tumor; (3) staging information; and (4) ability to derive Kadish stage. Abstracted covariates included sex, age, tumor grade, nodal status, year of diagnosis, derived Kadish stage, and treatment (surgery, radiotherapy (RT), CT). Outcomes included disease-specific (DSS) and overall (OS) survival. In SEER, CT and RT are classified as Yes vs No/Unknown. Uni- and multi-variable Cox analyses assessed CT treatment on DSS and OS, controlling for covariates noted above. To account for proportional hazards violations, such variables were either stratified or time-varying. Multiple imputation addressed missing data. A p < 0.05 was designated for statistical significance. Analyses were conducted using Stata ver 12. Results: 797 ON cases were included. In univariable analysis, CT treatment (yes vs no/unknown) was associated with inferior DSS (HR 2.81, 95% CI 2.11 3.74, p < 0.001) and OS (HR 2.03, 95% CI 1.63 2.54, p < 0.001). In multivariable analyses, CT was again associated with inferior DSS (HR 1.74, 95% CI 1.21, 2.51, p = 0.003) and OS (HR 1.71, 95% CI 1.26, 2.32, p = 0.001). Limiting analysis to those with local/regional disease treated with local therapy (surgery and/or radiation), CT remained associated with inferior outcomes [DSS (HR 2.78, 95% CI 1.63, 4.74, p < 0.001) and OS (HR 2.17, 95% CI 1.45, 3.27, p < 0.001)]. Sensitivity analyses ruled out chemotherapy misclassification as an explanation for our results. Conclusions: Our analysis does not support the use of chemotherapy to improve either DSS or OS in primary ON treatment. We controlled for known ON prognostic factors available from SEER. Other prognostic and treatment selection factors could exist for which we did not control. Chemotherapy may also beneficially affect outcomes other than DSS or OS. While concerns have been expressed regarding CT treatment misclassification in SEER, our analyses did not identify such misclassification as an explanation.