Unveiling cancer risk in ANCA-associated vasculitis: result from the Turkish Vasculitis Study Group (TRVaS).

To investigate cancer incidence in patients with ANCA-associated vasculitis (AAV), compare it with the age/sex-specific cancer risk of the Turkish population, and explore independent risk factors associated with cancer. This multicenter, incidence case-control study was conducted using the TRVaS registry. AAV patients without cancer history before AAV diagnosis were included. Demographic and AAV-related data of patients with and without an incident cancer were compared. Standardized cancer incidence rates were calculated using age-/sex-specific 2017 Turkish National Cancer Registry data for cancers (excluding non-melanoma skin cancers). Cox regression was performed to find factors related to incident cancers in AAV patients. Of 461 AAV patients (236 [51.2%] male), 19 had incident cancers after 2022.8 patient-years follow-up. Median (IQR) disease duration was 3.4 (5.5) years, and 58 (12.6%) patients died [7 with cancer and one without cancer (log-rank, p = 0.04)]. Cancer-diagnosed patients were older, mostly male, and more likely to have anti-PR3-ANCA positivity. The cumulative cyclophosphamide dose was similar in patients with and without cancer. Overall cancer risk in AAV was 2.1 (SIR) ((1.3-3.2), p = 0.004); lung and head-neck [primary target sites for AAV] cancers were the most common. In Cox regression, male sex and ≥ 60 years of age at AAV diagnosis were associated with increased cancer risk, while receiving rituximab was associated with decreased cancer risk. Cancer risk was 2.1 times higher in AAV patients than the age-/sex-specific cancer risk of the Turkish population population, despite a high rate of rituximab use and lower dose of cyclophosphamide doses. Vigilance in cancer screening for AAV patients covering lung, genitourinary, and head-neck regions, particularly in males and the elderly, is vital.