EPID-02. HISTORY OF ALLERGY OR ATOPY DECREASES RISK OF BRAIN METASTASIS IN LUNG CANCER AND MELANOMA

Abstract

Abstract Both allergy/atopy and autoimmune disease (AD) are associated with decreased prevalence of glioma. We leveraged cancer registry data combined with Medicare claims to investigate the effect of prior atopy/AD on incidence, and overall survival, of brain metastasis (BrM) in lung cancer (LC) and melanoma. Surveillance, Epidemiology and End. RESULTS: data linked to Medicare claims were obtained, containing cases of melanoma and LC diagnosed from 2008-2017. Patients < 65 years of age, enrolled in Medicare Advantage, with prior/subsequent cancer diagnosis, or missing variables were excluded. History of allergy/atopy/ or AD (≥6 months prior to primary cancer diagnosis) and BrM status were identified by ICD-9/ICD-10 codes and SEER variables. Treatment pattern was determined using ICD-9/ICD-10 and HCPCS/CPT codes. Time to BrM and overall survival among individuals diagnosed with BrM were estimated via Cox proportional hazards regression adjusted for age, sex, race/ethnicity, stage at diagnosis, treatment, and Charlson comorbidity score. Of the 154,203 and 66,593 cases of LC and melanoma, 18.6% and 2.5% developed BrM at any point, respectively. Among LC with BrM, 27% and 16% had atopy and/or AD (compared to 33% and 20% in LC without BrM), while there were 26% and 16% of cases with atopy and/or AD among melanoma with BrM (compared to 33% and 18% in melanoma without BrM). History of atopy was associated with decreased hazard of BrM in melanoma and LC (HR=0.73, p-value< 0.001 and HR=0.90, p=0.024, respectively). Among those with a BrM, both history of atopy and AD were associated with improved survival in LC (HR=0.90, p< 0.001 and HR=0.95, p< 0.001) but not melanoma. History of AD is associated with a moderate survival benefit in LC with BrM, while history of allergy/atopy decreased incidence of BrM in LC and melanoma. Further research is necessary to identify potential causes of this association.