Abstract 664: Surgery plus adjuvant radiation as a valid treatment option for primary central nervous system lymphoma (PCSNL)

Background: Recent studies of primary central nervous system lymphoma (PCNSL) have found an association between cytoreductive surgery and survival, challenging the traditional notion that surgery is not beneficial and potentially harmful. However, no studies have examined outcomes after surgery plus adjuvant treatment. We investigated treatment-related outcomes for surgery plus radiation using data from the Surveillance, Epidemiology, and End Results (SEER) Program. Methods: The SEER database was queried to collect cases of histologically confirmed non-Hodgkin's lymphoma within the CNS diagnosed between 1995-2014. Median survival times were determined by the Kaplan-Meier method and compared using the log-rank test. Predictors of overall survival and cause-specific survival were determined using the Cox proportional hazards regression model. Treatment modalities were categorized as biopsy alone, biopsy plus radiation therapy (RT), surgery alone, and surgery + RT. Biopsy alone was used as the reference category. Subgroup analysis stratified patients by extent of surgical resection and recursive partition analysis (RPA) risk group. Results: We identified 5,417 cases that met search criteria, 39% of which received surgical resection. Median survival times for biopsy alone (n=1,824, 34%), biopsy + RT (n=1,460, 27%), surgery alone (n=1,222, 23%), and surgery + RT (n=911, 17%) were 7, 8, 20, and 27 months, respectively (p