Frederiksberg, Denmark—While tumor necrosis factor inhibitors (TNFi) effectively reduce inflammation in psoriatic arthritis (PsA), concerns have been raised about a possible association between treatment with TNFi and increased cancer risk.

The results of a study presented at the Annual European Congress of Rheumatology (EULAR 2019) suggest that is not the case, however.

The study analyzes the risk of primary cancer in more than 8,000 TNFi-treated psoriatic arthritis patients from Sweden, Denmark, Iceland, and Finland. Researchers from Bispebjerg and Frederiksberg Hospital and colleagues report that results demonstrated no increase in risk of overall cancer or site-specific cancers, including colorectal, lung, malignant melanoma, pancreas, brain, female breast, endometrial, and prostate.

“TNF inhibitors have a well-established efficacy and safety profile in patients with psoriatic arthritis and we welcome these data which contribute to our understanding in the complex area of cancer risk,” said Professor Hans Bijlsma, EULAR’s president.

The study notes a significant increase in malignant lymphomas observed within the trial (standardized incidence ratio: 1.84, 95% CI, 1.20-2.82). Researchers explain, however, that the cause—whether TNFi treatment or psoriatic arthritis itself—is not clear.

“There is limited data on lymphoma risk in psoriatic arthritis, however, an excess risk has been reported for several other chronic inflammatory rheumatic diseases with a well-established doubled average risk in patients with rheumatoid arthritis,” they point out.

For the study, PsA patients were followed from first registration with TNFi-treatment in ARTIS (Sweden), DANBIO (Denmark), ICEBIO (Iceland), or ROB-FIN (Finland) and linked to the national cancer registry in each country. The risk of primary cancer among TNFi-treated PsA patients was compared with general-population cancer rates standardized to age, sex, and calendar period within each country.

For all cancers, the standardized incidence ratios of TNFi-treated patients from ARTIS, DANBIO, ICEBIO, and ROB-FIN were 0.94 (0.80-1.10), 0.99 (0.77-1.26), 1.71 (0.88-2.99), and 1.28 (0.82-1.90), respectively.

“Our study provides convincing evidence that the use of TNF inhibitors does not increase the risk of overall cancer in patients with psoriatic arthritis,” said coauthor Lene Dreyer, PhD, of Aalborg University Hospital in Denmark. “Further analysis is needed to assess whether the observed increase in malignant lymphomas is due to the psoriatic arthritis disease or the TNFi treatment.”

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