Abatacept initiation in rheumatoid arthritis and the risk of cancer: a population-based comparative cohort study

To assess whether abatacept as initial biological DMARD (bDMARD) in the treatment of RA, when compared with other bDMARDs, is associated with an increased risk of cancer overall and by specific cancer sites (breast, lung, lymphoma, melanoma and non-melanoma skin cancer).

We performed a population-based cohort study among patients newly treated with bDMARDs within the US-based Truven MarketScan population and Supplemental US Medicare from 2007 to 2014. Cox proportional hazards models were used to estimate hazard ratios and 95% CIs of any cancer (and specific cancers) associated with initiation of abatacept, compared with initiation of other bDMARDs, adjusted for age and deciles of the propensity score.

The cohort included 4328 patients on abatacept and 59 860 on other bDMARDs, of whom 409 and 4197 were diagnosed with any cancer during follow-up (incidence rates 4.76 per 100 per year and 3.41 per 100 per year, respectively). Compared with other bDMARDs, the use of abatacept was associated with an increased incidence of cancer overall (hazard ratioadjusted 1.17; 95% CI 1.06, 1.30). Analyses by specific cancer sites showed a significantly increased incidence of non-melanoma skin cancer (hazard ratioadjusted 1.20; 95% CI 1.03, 1.39), but no significant difference for other specific cancer sites.

The use of abatacept as first bDMARD in the treatment of RA was associated with a slight increased risk of cancer overall and particularly non-melanoma skin cancer, compared with other bDMARDs. This potential signal needs to be replicated in other settings.