Malignancies in Patients with Antineutrophil Cytoplasmic Antibody-associated Vasculitis: A Population-based Cohort Study

Objective. Patients with ANCA-associated vasculitides (AAV) exhibit higher rates of malignancy than the general population. 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, and eosinophilic GPA] 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 observation period of about 1500 person-years, 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) < 10 g were not associated with higher incidence of cancers other than SCC (SIR 1.63, 95% CI 0.8–2.9).

Conclusion. In contrast to previous 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 < 10 g CYC.