Background/Purpose: 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, hospitalized subgroup of patients. Most of the studies allowed for a wide time interval between IgAV and cancer appearance, not necessarily reflecting a causative link. The aim of our longitudinal prospective study was to look for the potential association between IgAV and cancer in an unselected adult IgAV population.

Methods: We analysed medical records of prospectively followed, histologically proven adult IgAV cases at our secondary/tertiary rheumatology centre form a well-defined referral region between 1 January 2010 and 31 May 2016, who were followed until 31 May 2017. Patients with at least 6-month follow up were included in the analysis. 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 6month 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).

Results: During the 77-month observation period we identified 171 new IgAV cases. 2 patients died in the acute disease phase due to vasculitis, and 7 during the first 6 months of follow-up for reasons other than IgAV or cancer. 18 patients were lost to follow-up. The remaining 144 patients (55% male, median (IQR) age 66 (44-77) years) were followed for a median (IQR) of 23 (13-34) months. At the time of IgAV diagnosis, 4/144 (2.8%) had active, previously diagnosed malignant disease. In 2/144 patients (1.4%) a new cancer was diagnosed. 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) 82 (80-83) vs. 64 (44-76) years; p=0.003) 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 4.2%. Compared to the 4.6% prevalence of cancer in our general population and the relative risk of cancer in our IgAV cohort was 0.91 (p=0.817; 95% CI 0.42-2.00). The age adjusted incidence rate of cancer was 13.9 per 1000 patient years. The annual age adjusted incidence rate of cancer in our citizens, acquired from NCR, was 31.2 per 1000 patient years and the standardised incidence ratio for our IgAV cohort was 0.89 (p=0.781; CI 0.11–3.21).

Conclusion: In our cohort of unselected adult IgAV cases, we did not confirm the previous observations of the association of IgAV and cancer.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/is-there-an-association-between-adult-iga-vasculitis-and-cancer/