Asthma, asthma medications, and prostate cancer risk

Background: The aim of this study was to assess whether a history of asthma or the use of asthma medications is associated with prostate cancer risk. Methods: Of 16,934 men participating in the Melbourne Collaborative Cohort Study, 1,179 were diagnosed with prostate cancer during an average follow-up of 13.4 years to the end of December 2007. Information on asthma history was obtained at baseline interview. Participants were asked to bring their current medications to the study center. The names of the drugs were entered into a form and coded. Asthma medications were categorized into four groups and corresponding hazard ratios (HR) were estimated from Cox regression models adjusted for country of birth. Results: Asthma was associated with a small increase in prostate cancer risk [HR 1.25; 95% confidence interval (95% CI), 1.05-1.49]. The HRs for use of medications were 1.39 (95% CI, 1.03-1.88) for inhaled glucocorticoids, 1.71 (95% CI, 1.08-2.69) for systemic glucocorticoids, 1.36 (95% CI, 1.05-1.76) for bronchodilators, and 0.78 (95% CI, 0.45-1.35) for antihistamines. The HRs for asthma and asthma medication use changed only slightly after mutual adjustment. Conclusions: A history of asthma and the use of asthma medications, particularly systemic glucocorticoids, are associated with an increased risk of prostate cancer, although it is difficult to disentangle the effects of asthma medications from those of asthma per se. Impact: These findings, if confirmed in independent studies, might lead to the identification of new risk factors for prostate cancer.