Cancer preceding Wegener's granulomatosis: a case-control study.

Objective: To investigate whether patients with WG have an increased risk of malignancies prior to and/or around the time of the vasculitis diagnosis, as suggested by previous studies.
Methods: A total of 293 WG patients were included in the study. Ten gender- and age-matched controls were selected randomly for each patient from the Danish Central Population Register. Information on malignancies was obtained through the Danish Cancer Registry. Occurrence of malignancies before WG diagnosis among patients and before WG diagnosis of their matched case among controls (reference date) was compared by calculation of prevalence odds ratios (OR).
Results: Twenty-six patients were diagnosed with cancer before WG, while 194 controls were diagnosed with cancer before the reference date (OR 1.4; 95% CI 0.9, 2.2). Among specific malignancies, a significantly increased prevalence was found for testis cancer (OR 6.4; 95% CI 1.1, 38) based on two patients, who developed testis cancer >10 years before WG. The overall prevalence of malignancies diagnosed <2 years before WG was not significantly increased (OR: 1.6; 95% CI: 0.8, 3.4), but non-melanoma skin cancer occurred with an increased prevalence within this time interval (OR 4.0; 95% CI 1.4, 12).
Conclusions: We did not find clear evidence of an increased prevalence of preceding cancer in our WG cohort, indicating that shared risk factors are of minor importance for the excess of malignancies that occur in WG patients after the vasculitis diagnosis. Furthermore, our current and previously reported latency analyses do not substantiate that serious malignancies play a significant role in the pathogenic events that trigger development of WG.