Survival Outcomes in Older Adults with Axial Spondyloarthritis and Concomitant Cancer

OBJECTIVE: The objective of this study was to determine survival outcomes in older adults with axial spondyloarthritis (axSpA) and concomitant cancer. METHODS: We conducted a population-based study using Medicare claims data linked to Surveillance, Epidemiology, and End Results data to determine overall survival (OS) and cancer-specific survival (CSS) in patients aged ≥66 years with in situ, localized, regional, or distant breast cancer (BC), prostate cancer (PCa), lung cancer (LC), or colorectal cancer (CRC), with and without axSpA, diagnosed January 2006 to December 2019 using ICD-O-3 site and histology codes. Patients with axSpA were matched to 2-5 controls without axSpA using cancer type, age at cancer diagnosis, sex, stage, and year of cancer diagnosis. We censored OS and CSS at 5 years and estimated rates using Kaplan-Meier analyses with log-rank tests. Stratified Cox proportional hazard regression models were performed for each cancer type, with CSS analyzed under the competing risks framework. RESULTS: We included 6,095 patients (2,061 BC, 1,988 PCa, 1,229 LC, 817 CRC) with axSpA and 30,386 controls. Mean ages ranged from 74 (BC, PCa, LC) to 77 (CRC). No statistically significant differences in OS or CSS rates were observed between BC, PCa, or LC patients with axSpA compared to controls. CRC patients with axSpA had higher 5-year OS (adjusted hazard ratio (aHR): 0.78 (95% CI: 0.67-0.91, P=0.002)) and CSS (aHR: 0.76 (95% CI: 0.59-0.99, P= 0.04)) compared to controls. CONCLUSIONS: Older patients with axSpA and BC, PCa, and LC had similar OS and CSS compared to controls. Among patients with CRC, axSpA was associated with higher OS and CSS.