Rheumatoid arthritis, anti-tumour necrosis factor treatment, and risk of squamous cell and basal cell skin cancer: cohort study based on nationwide prospectively recorded data from Sweden

A small to moderately increased risk of basal cell cancer was seen in biologics-naive rheumatoid arthritis patients, with no further effect of TNF inhibitors. For squamous cell cancer, the risk was nearly doubled in biologics-naive patients, with a further 30% increase in risk among patients treated with TNF inhibitors; this translates to one additional case for every 1600 years of treatment experience, assuming that this association reflected causality. Vigilance regarding skin malignancies may be advisable in rheumatoid arthritis, irrespective of TNF inhibitor treatment. Most of the increase in risk for non-melanoma skin cancer in patients with rheumatoid arthritis treated with TNF inhibitors originates from factors other than that treatment.