No link between cancer and tumor necrosis factor inhibitor (TNFi) use in psoriatic arthritis

The results of a study presented today at the Annual European Congress of Rheumatology (EULAR 2019) suggest that overall cancer risk is not linked to tumour necrosis factor inhibitor (TNFi) use in psoriatic arthritis.

The study analyses the risk of primary cancer in over 8,000 TNFi-treated psoriatic arthritis patients from Sweden, Denmark, Iceland, and Finland. Results demonstrated no increase in risk of all cancer, as well as 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, President, EULAR.

There was a significant increase in malignant lymphomas observed within the trial (standardised incidence ratio: 1.84, 95% confidence interval: 1.20-2.82). However, it is not clear if this is due to the psoriatic arthritis disease or the TNFi treatment. 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.

"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 Professor Lene Dreyer, Aalborg University Hospital, Aalborg, 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."

Psoriatic arthritis is a chronic inflammatory disease that affects the joints, causing pain and disability. The disease often causes swelling of the fingers and toes, mainly because of joint inflammation. Tumour necrosis factor inhibitors have been shown to be efficacious in psoriatic arthritis. However, tumour necrosis factor (TNF) also plays a complex role in the development and progression of cancer and so the use of TNFi may theoretically increase the risk of tumour development.

This population-based cohort study includes 5,218, 2,039, 270 and 526 TNFi-treated psoriatic arthritis patients from ARTIS (Sweden), DANBIO (Denmark), ICEBIO (Iceland), and ROB-FIN (Finland) respectively. Patients were followed from first registration with TNFi-treatment and linked to the national cancer registry in each country (patients with a history of cancer were excluded). The cancer rates were compared with the general population standardised to age, sex and calendar period within each country. Standardised incidence ratios were estimated for both any cancer and site-specific cancers of interest.