The Association Between Allopurinol Use And Urologic Malignancies: A Nested Case-Control Study

435 Background: Oxidative stress may be involved in tumorigenesis processes. Uric acid is an important natural antioxidant that may reduce oxidative stress. Allopurinol is a commonly used uric acid lowering agent. There are conflicting data regarding the association between allopurinol use and cancer incidence. In the present nested case control study, we aimed to evaluated the association between allopurinol use and urologic malignancies in a large western population. Methods: conducted a nested case-control study within a population-representative database from the United Kingdom (THIN). Study cases were defined as individuals with any diagnostic code of prostate cancer, bladder cancer, or renal cell carcinoma. For every case, four eligible controls were matched on age, gender, practice site, time of diagnosis, and duration of follow-up. Exposure of interest was any allopurinol use prior to cancer diagnosis. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for urologic malignancies were estimated using conditional logistic regression. Adjustment was performed for factors including smoking, BMI, and diabetes. Results: The study population included: for bladder cancer 13440 and 52421 matched controls, prostate cancer 27212 cases and 105940 controls, RCC 1547 cases and 6066 controls. Allopurinol use was associated with a significantly increase of risk for bladder cancer (adjusted OR 1.2, 95%CI 1.09-1.32, p<0.001). prostate cancer (adjusted OR 1.1, 95%CI 1.03-1.,17, p=0.003), RCC (adjusted OR 1.32, 95%CI 1-1..75, p=0.05). In a sensitivity analyses we observed similar associations when alopurinol use was initiated more than two years prior to cancer diagnosis, for bladder cancer (adjusted OR 1.2, 95%CI 1.08-1.33, p=0.001), prostate cancer (adjusted OR 1.09, 95%CI 1.02-1.16, p=0.01), RCC (adjusted OR 1.09, 95%CI 0.78-1.53, p=0.62). Conclusions: Allopurinol use may be associated with an increased risk for urologic malignancies.