Background/objectives: Patients with AAV are known to have an increased risk for the development of malignancies, which has been largely attributed to immunodeficiency or side effects induced by immunosuppressive treatments. Because there is a considerable latency period for cancer development after exposure to immunosuppressive treatments, little data are available on the incidence of cancer for large cohort of patients with AAV and long follow-up. The aim of this study is to describe the cumulative incidence of cancer in patients with AAV who participated in the EUVAS therapeutic clinical trials from 1995 to 2012. Methods: 848 patients with AAV from 17 European countries were included in the present study. Information was retrieved from questionnaires sent to the principal investigators of the original RCTs (MEPEX, NORAM, CYCAZAREM, CYCLOPS, IMPROVE, RITUXVAS and MYCYC). Results: Among the total of 848 patients (median follow-up: 8 years, IQR: 2.2–8.8), 149 patients were diagnosed with 181 malignancies. The 10-year cumulative incidence of cancer was estimated at 20.6%. The median duration of start of AAV therapy-to-time of cancer diagnosis was 4.96 years (IQR: 2.24-8.83). The most common cancer types were skin cancer (37.4%), out of which 6 were melanoma and 62 non-melanoma skin cancer, followed by gastrointestinal cancer (12.6%) and prostatic cancer (9.9%). Patients who developed cancer were significantly older at randomization than those who did not (62±12 vs 57±14 years) (p<0.001). Considering both remission-induction and remission-maintenance therapies, 94% of the patients received cyclophosphamide, 68.4% azathioprine, 28.2% mycophenolate, 11.4% methotrexate and 10.4% rituximab during the observation period. Six out of the 28 patients, who were treated with rituximab and two pulses of IV cyclophosphamide as induction therapy, developed cancer. Diagnosis of cancer significantly predicted shorter survival (Log rank=9.2, p=0.002). Conclusions: Our findings, which were derived from a large number of patients with AAV enrolled in clinical trials over the past 25 years, estimates the 10-year cumulative incidence of malignancies following the start of AAV therapy at 20.6%. The development of cancer is tightly associated with decreased survival. Analyses of standardized incidence ratios, using the cancer incidence of the background populations as reference, are underway. Disclosures: None