Risk of nonmelanoma skin cancer in patients with psoriatic arthritis and according to bDMARD treatment—a cohort study from the Nordic Arthritis Research Collaboration

Objectives To investigate if psoriatic arthritis (PsA) itself and if biological disease-modifying antirheumatic drugs (bDMARDs) used in PsA are associated with increased risks of nonmelanoma skin cancer (NMSC). Methods From nationwide health and clinical rheumatology registers in 4 Nordic countries, we identified patients with PsA who between 2010 and 2021 started a: (i) tumour necrosis factor inhibitor (TNFi), or (ii) non-TNFi bDMARD, or were (iii) b/targeted synthetic (ts)DMARD naïve. For Sweden and Denmark, we identified incident patients with PsA (2010-2021) and corresponding general population (GP) comparator subjects. Using ever-treated follow-up, incidence rates and adjusted hazards ratios (aHRs) with 95% CIs were calculated for NMSC overall, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC), respectively. Results We identified 619 NMSCs among incident patients with PsA (n = 23,553). We observed 221 NMSCs in TNFi-treated (n = 9999), 34 NMSCs in non-TNFi bDMARD-treated (n = 2200), and 433 NMSCs in b/tsDMARD-naïve (n = 19,089) PsA. The aHR of NMSC for incident PsA vs GP was 1.20 (1.11-1.31). Pooled aHRs for NMSC overall were 1.24 (1.03-1.50) with TNFi and 1.11 (0.75-1.63) with non-TNFi bDMARDs vs b/tsDMARD-naïve PsA. Corresponding aHRs of BCC were 1.21 (0.93-1.58) for TNFi and 0.85 (0.42-1.69) for non-TNFi bDMARDs, whereas aHRs for SCC were 1.46 (0.84-2.56) and 2.37 (0.95-5.90). Conclusions Increased risks of NMSC (SCC in particular) were found in patients with PsA compared with the GP. Compared with b/tsDMARD-naïve PsA, TNFi was associated with an increased risk of NMSC overall, whereas a nonsignificantly increased risk of SCC was seen for non-TNFi bDMARDs. However, causality between bDMARD use and NMSC in PsA remains uncertain.