To compare the risk of keratinoctye skin cancer (basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)) in patients treated for rheumatoid arthritis (RA) compared with the general population, and to determine whether anti-tumour necrosis factor (TNF) therapy exacerbates this risk.
Patients with RA enrolled in the British Society for Rheumatology Biologics Register, a prospective national cohort established in 2001 to monitor the safety of anti-TNF, were followed until 2008. 11 881 patients treated with anti-TNF were compared with 3629 patients receiving non-biological disease-modifying antirheumatic drugs (nbDMARD). Standardised incidence ratios (SIR) were calculated for each cohort and rates between cohorts were compared using Cox proportional HR, adjusted using inverse probability of treatment weighting.
SIR for skin cancer was increased in both cohorts compared with the English population: SIR 1.72 (95% CI 1.43 to 2.04) anti-TNF; 1.83 (95% CI 1.30 to 2.50) nbDMARD only. In patients without previous skin cancer, BCC incidence per 100 000 patient-years was 342 (95% CI 290 to 402) after anti-TNF and 407 (95% CI 288 to 558) after nbDMARD. HR after anti-TNF adjusted for treatment weighting was 0.95 (95% CI 0.53 to 1.71). SCC incidence per 100 000 patient-years: anti-TNF 53 (95% CI 33 to 79); nbDMARD 43 (95% CI 12 to 110); adjusted HR 1.16 (95% CI 0.35 to 3.84).
Skin cancers were increased among treated patients with RA. No evidence was found that anti-TNF therapy exacerbates the risk of BCC or SCC but this cannot be excluded. Patients with RA should use sun protection and be monitored for skin cancer.