Malignancies in patients with ANCA-associated vasculitis – A population based cohort study

Objective Patients with ANCA-associated vasculitides (AAV) exhibit higher rates of malignancy than the general population. In this study, we assessed whether the cancer risk is increased in a well-characterized population-based cohort of AAV in southern Sweden, followed for a median time of 8 years. Methods With case record review, the outcomes and malignancy development in a cohort of 195 patients with AAV (granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA), diagnosed between 1997 and 2010, were assessed. The patients were followed until death or December 31, 2015. The age- and sex-standardized incidence ratios (SIR) were estimated using the Swedish population data as a reference. Results During the approximately 1500 person-years observation period, we found 60 cancers in 52 of the 195 patients. SIR (95% CI) was 2.8 (2.1-3.6) for cancers at all sites, 1.8 (1.3-2.5) for all cancers excluding squamous cell carcinoma (SCC), 12.9 (8.4 -18.8) for SCC, 4.3 (1.4-10.0) for bladder cancer, and 7.0 (1.4-20.5) for pancreatic cancer. Cumulative doses of cyclophosphamide (CYC) less than 10g were not associated with higher incidence of cancers other than SCC (SIR 1.63 (95% CI: 0.8-2.9). Conclusion In contrast to recent publications assessing malignancy risk in patients with AAV, we show in this population-based cohort of patients, a persistent increased risk for overall malignancy, bladder cancer, and pancreatic cancer as well as a markedly increased risk for SCC. There was no increase in incidence of cancers other than SCC for those treated with less than 10 grams CYC.