Objectives: To report the incidence of malignancy in a large single-centre cohort in Belgium of patients with spondyloarthritis (SpA) treated with one or more anti-TNF therapies and to compare the results with the incidence of malignancy in the Belgian population.
Methods: From September 2000 until March 2010, all SpA patients that started treatment with one or more anti-TNF therapies were included in this single-centre prospective longitudinal observational study. The primary outcome of this study was the incidence of malignancy after starting anti-TNF treatment. Incidence rates were compared with the incidence rates of malignancy in Belgium in 2008 for the 45-50 year-old population, as documented by the Belgian Cancer Registry.
Results: 231 patients with a mean age of 47.86 y were included for a total of 1020.74 patient years of treatment and 1199.83 patient years follow-up after the start of treatment. In our study population, 6 out of 231 patients (2.6 %) developed a malignancy after the start of anti-TNF treatment. The overall incidence rate of malignancy in our study population is 500.1 per 100000 patient years, indicating a higher incidence compared to the Belgian population. We see a higher incidence rate in females as well in males; standardised incidence ratios are in the same range for both (154.3 for females and 130.6 for males).
Conclusions: We see a tendency towards a higher incidence of malignancy in SpA patients treated with anti-TNF therapy. However, it is not clear whether this increased risk is disease-related or treatment-related.