title: Rheumatoid arthritis, anti-tumour necrosis factor therapy, and risk of malignant melanoma: nationwide population based prospective cohort study from Sweden.
abstract: OBJECTIVE
  To investigate the potential association between tumour necrosis factor (TNF) inhibitor treatment and malignant melanomas in rheumatoid arthritis, melanoma risks in rheumatoid arthritis patients not treated with biological drugs, and risk of all site cancer with TNF inhibitors as used in rheumatoid arthritis.
  
  
  METHODS
  Population based cohort study.
  
  
  METHODS
  Prospectively recorded data from national clinical, health, and demographic registers in Sweden 2001-10. Patients with rheumatoid arthritis treated (n = 10,878) or not (n = 42,198) with TNF inhibitors and matched general population comparators (n = 162,743).
  
  
  METHODS
  The primary outcome was first invasive melanoma in people without any history of invasive cancer of any type. Hazard ratios were estimated using Cox regression, comparing non-biological drug treated rheumatoid arthritis patients with the general population comparator and TNF inhibitor treated rheumatoid arthritis patients with those not treated with biological drugs. Secondary outcomes included in situ melanomas, second primary melanomas, and all site cancer.
  
  
  RESULTS
  113 first invasive melanomas occurred in rheumatoid arthritis patients not treated with biological drugs, and 393 occurred in the general population comparator cohort. Rheumatoid arthritis patients not treated with biological drugs were not at significantly increased risk of melanoma compared with the general population (hazard ratio 1.2, 95% confidence interval 0.9 to 1.5). 38 first invasive melanomas occurred in rheumatoid arthritis patients treated with TNF inhibitors; these patients had an increased risk of melanoma compared with rheumatoid arthritis patients not treated with biological drugs (hazard ratio 1.5, 1.0 to 2.2; 20 additional cases per 100,000 person years). The risk of a second primary melanoma was non-significantly increased (hazard ratio 3.2, 0.8 to 13.1; n=3 v 10) in rheumatoid arthritis patients treated with TNF inhibitors compared with those not treated with biological drugs.
  
  
  CONCLUSIONS
  Overall, patients with rheumatoid arthritis who have not been treated with biological drugs are not at increased risk of invasive melanoma compared with the general population. Rheumatoid arthritis patients selected for TNF inhibitor treatment are not at increased overall risk for cancer but have a 50% increased relative risk of invasive melanoma. Given the small increase in absolute risk, these finding may not markedly shift the overall risk-benefit balance of TNF inhibitors as used in clinical practice but might do so in patients at high risk of melanoma for other reasons.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, SE-171 76 Stockholm, Sweden. pauline.raaschou@karolinska.se
authors.forename: Pauline
authors.initials: P
authors.lastname: Raaschou
authors.forename: Julia F
authors.initials: JF
authors.lastname: Simard
authors.forename: Marie
authors.initials: M
authors.lastname: Holmqvist
authors.forename: Johan
authors.initials: J
authors.lastname: Askling
mesh_terms: D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000188:drug therapy* / Q000453:epidemiology*; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000139:chemically induced* / Q000453:epidemiology; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D012306:Risk; D013548:Sweden / Q000453:epidemiology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha