Background Tumor necrosis factor inhibitors (TNFi) have become a mainstay treatment for chronic inflammatory diseases such as Rheumatoid Arthritis (RA). Based on concerns that TNFi might increase the risk of cancer recurrence, in combination with limited evidence, most clinical guidelines advice against the use of this therapy in patients with a history of cancer during the last five or ten years.
Objectives To investigate the risk of breast cancer recurrence in female patients with RA and a history of breast cancer starting treatment with TNFi, taking RA, breast cancer and comorbidity-related factors into account.
Methods Nationwide, population-based matched cohort study based on prospectively recorded data in Sweden.120 TNFi-treated (1999-2010) and 120 matched biologics-naïve individuals with RA and a history of equally recent/distant breast cancer were identified through register linkages. Through register linkages and chart review, individuals were followed for first recurrence of breast cancer through 2011. Hazard ratios (HRs) for recurrence were calculated using Cox regression.
Results The median time from breast cancer diagnosis until TNFi treatment/start of follow-up was 9.4 years. Modest differences in breast cancer characteristics and/or treatment among TNFi-treated and biologics-naive were noted at time of breast cancer diagnosis. Median follow-up was 4.9 years from TNFi start (4.6 years among biologics-naïve).
Among the TNFi-treated, 9 developed a breast cancer recurrence (crude incidence rate 15/1000 person-years) during follow-up, compared to 9 among the matched biologics-naïve (16/1000 person-years). The corresponding HR was 0.8 (95% CI 0.3-2.1). Adjusting for the observed differences in breast cancer characteristics, the HR was 1.1 (95% CI 0.4-2.8).
The HR for recurrence was 1.4 (95% CI 0.2-8.6) among patients who started TNFi within five years from their breast cancer diagnosis, and 0.8 (95% CI 0.3-2.4) among patients who started TNFi more than five years after their breast cancer.
Conclusions Among patients with RA and a history of breast cancer, those who started TNFi treatment did not experience more breast cancer recurrences than RA patients treated otherwise. The generalizability of our findings to women with a very recent or a poor prognosis breast cancer remains unknown.
Acknowledgements We thank Mattias Lundström for assisting in the collection of data
Disclosure of Interest None declared