THU0448 Is there an association between adult iga vasculitis and cancer?
Authors: J. Ostrovršnik, &Zcaron;. Rotar, R. Ješe, M. Tomši&ccaron;, A. Ho&ccaron;evar
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> An increased incidence rate of cancer has been reported in adult patients with IgA vasculitis (IgAV). These conclusions are mostly based on observations in severely ill, hospitalised subgroup of patients. Most of the studies allowed for a wide time interval between IgAV and cancer appearance, not necessarily reflecting a causative link. <h3>Objectives</h3> The aim of our study was to look for the potential association between IgAV and cancer in an unselected adult IgAV population. <h3>Methods</h3> We analysed medical records of prospectively followed, histologically proven adult IgAV cases at our secondary/tertiary rheumatology centre between 1 <sup>January 2010</sup> and 30 June 2017, who were followed until 31 December 2017 and lived in a well-defined referral region. We identified cancer as concurrent with IgAV, if the patients had active cancer or a relapse of cancer or newly-diagnosed cancer diagnosed up to 6 months prior or 6 months after IgAV diagnosis. Cancers developing after 6 months of follow up were labelled as unrelated to IgAV. We used appropriate descriptive statistical methods, and the Fisher's exact and Mann-Whitney U tests to assess differences of clinical characteristics in acute phase of IgAV, between the cancer and non-cancer groups. The national prevalence and age adjusted incidence rates of cancer from a well-defined referral region were obtained from National cancer registry (NCR). <h3>Results</h3> During the 90 months of observation we identified 196 new IgAV cases. 2 patients died in the acute disease phase due to vasculitis, and 8 during the first 6 months of follow-up for reasons other than IgAV or cancer. 20 patients were lost to follow-up. The remaining 166 patients (55% male, median (IQR) age 63<sup>43–76</sup> years) were followed for a median (IQR) of 20<sup>11 - 32</sup> months. At the time of IgAV diagnosis, 6/166 (3.6%) had active, previously diagnosed malignant disease (prostatic cancer in 4, among which one also had cancer of urinary bladder, and sarcoma in 2 patients). In 2/166 patients (1.2%) a new cancer was diagnosed at presentation and in 2/166 (1.2%) during follow-up. One of the patients with an active cancer of urinary bladder, was treated with antibiotics for urinary tract infection prior to IgAV diagnosis, and was also on chemotherapy. The patients with cancer were older (median age (IQR) 80<sup>77–83</sup> vs. 64<sup>44–77</sup> years; p=0.002) but their presenting features of IgAV, and the initial IgAV treatment did not significantly differ from those without cancer. At the end of the observation period, the prevalence of cancer in our cohort was 6.0%, compared to the 4.8% prevalence of cancer in our general population and the relative risk of cancer in our IgAV cohort was 1.25 (95% CI 0.687–2.29; p=0.461). The age adjusted incidence rate of cancer was 11.4 per 1000 patients per year. The annual age adjusted incidence rate of cancer in our citizens, acquired from NCR, was 8.9 per 1000 adults and the standardised incidence ratio for our IgAV cohort was 1.62 (CI 0.441–4.15; p=0.472). <h3>Conclusions</h3> In our cohort of unselected adult IgAV cases, we did not confirm the previous observations of the association of IgAV, and cancer. <h3>Disclosure of Interest</h3> None declared