title: TNF inhibitor therapy and risk of breast cancer recurrence in patients with rheumatoid arthritis: a nationwide cohort study.
abstract: OBJECTIVE
  To investigate the risk of breast cancer recurrence in rheumatoid arthritis (RA)-patients with tumour necrosis factor inhibitor (TNFi) treatment and a history of breast cancer, taking several breast cancer, comorbidity and RA-related prognostic factors into account.
  
  
  METHODS
  143 female TNFi-treated patients (1999-2010) with RA and a history of breast cancer before start of TNFi were identified through register linkages, and matched 1:1 from a cohort of 1598 comparable biologics-naive individuals. 120 TNFi-treated and 120 matched biologics-naive individuals with a history of equally recent/distant breast cancer met the eligibility criteria and comprised the final study population. The primary outcome was first recurrence of breast cancer. Through register-linkages and chart review, individuals were followed until 2011. 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 individuals were noted at time of breast cancer diagnosis. Median follow-up from TNFi start was 4.9 years (4.6 years among biologics-naive). Among the TNFi-treated, 9 developed a breast cancer recurrence (crude incidence rate 15/1000 person-years) during follow-up, compared with 9 among the matched biologics-naive (16/1000 person-years). The adjusted corresponding HR was 1.1 (95% CI 0.4 to 2.8).
  
  
  CONCLUSIONS
  Among patients with RA and a history of breast cancer, those who started TNFi-treatment did not experience more breast cancer recurrences than patients with RA treated otherwise. The generalisability of our findings to women with a very recent or a poor prognosis of breast cancer remains unknown.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet Stockholm, Sweden Clinical Pharmacology Unit Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Pauline
authors.initials: P
authors.lastname: Raaschou
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet Stockholm, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Frisell
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet Stockholm, Sweden Rheumatology Unit, Department of Medicine Solna, Karolinska Institutet Stockholm, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Askling
mesh_terms: D000068879:Adalimumab / Q000627:therapeutic use*; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism; D001943:Breast Neoplasms / Q000150:complications* / Q000453:epidemiology; D004359:Drug Therapy, Combination; D000068800:Etanercept / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha; D000068879:Adalimumab; D000068800:Etanercept
keywords: Anti-TNF; Epidemiology; Rheumatoid Arthritis; Treatment