Incidence of Common Cancers in Users of Antimuscarinic Medications for Overactive Bladder: A Danish Nationwide Cohort Study

摘要

Abstract The purpose of this study was to estimate the incidence rate ( IR ) of 10 common cancers in new users of antimuscarinic overactive bladder ( OAB ) medications. We conducted a cohort study using data recorded in Danish registers for patients newly exposed to the OAB drugs, darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine or trospium in years 2004–2012, aged ≥18?years and without cancer before treatment initiation. We estimated IR s for each study cancer (bladder, breast, colorectal, lung, melanoma, non‐Hodgkin lymphoma, pancreas, prostate, renal and uterine), standardised by age and sex and explored IR trends over time since treatment initiation. For all cancer analyses, only the first incident targeted cancer was considered. Of 72,917 patients (60% women; mean age at treatment start: 66?years), 3475 developed a study cancer during 259,072 person‐years of follow‐up. The most common study cancers were prostate (48.1% of study cancers in men), breast (40.0% of study cancers in women) and lung (15.4% of all study cancers). The overall standardised study cancer IR was 5.4 per 1000 person‐years (95% confidence interval, 5.3–5.6); IR s were similar across individual OAB drugs. The standardised IR s for bladder and prostate cancers, which have symptoms in common with OAB , were highest in the first 6?months of treatment initiation and lower thereafter. In contrast, IR s for other study cancers were nearly constant during follow‐up. Cancer IR s did not vary substantially by individual OAB drug. Protopathic bias is a plausible explanation for the higher rates of bladder and prostate cancers observed soon after starting OAB drug treatment.