Survival in patients with rheumatoid arthritis and early breast cancer treated with tumor necrosis factor inhibitors.

Background: There have been concerns about the use of tumor necrosis factor inhibitors (TNFi) for autoimmune disease in patients with recently diagnosed cancer. We assessed the survival of patients with rheumatoid arthritis (RA) and newly diagnosed early breast cancer (BC) treated with TNFi in the first two years after BC diagnosis.

Methods: We identified patients in two datasets: (1) Optum's de-identified Clinformatics^® Data Mart Database (CDM), (2) Surveillance, Epidemiology, and End Results program (SEER) and Texas Cancer Registry (TCR) Medicare-linked cohort. We grouped patients according to whether they received TNFi, conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) only, or no DMARDs within 2 years after BC. Outcomes were overall survival (OS) and BC-specific survival (BCSS). We conducted landmark analyses at years 1 and 2, with multivariable Cox regressions using propensity scores for adjustment.

Results: In the first year after BC, 165/970 (17.0%) and 201/1246 (16.1%) patients received TNFi in CDM and SEER/TCR-Medicare respectively. In the 1 year landmark, no significant differences in OS were observed between patients treated with TNFi and patients treated with csDMARDs only in CDM (hazard ratio [HR] = 0.77, 95% confidence interval [CI] 0.42-1.40) or SEER/TCR-Medicare (HR = 0.84, 95% CI 0.54-1.31). BCSS (SEER/TCR-Medicare) was better in patients receiving TNFi than in those receiving csDMARDs only (HR = 0.28, 95% CI 0.08-0.98). In CDM, glucocorticoid therapy had worse OS than those without glucocorticoids (HR = 2.18, 95% CI 1.13-4.18). This was also observed in SEER/TCR-Medicare (not statistically significant). Similar results were observed for the 2 year landmark.

Conclusions: TNFi treatment during the first two years after early BC was not associated with worse survival.