INCREASED RISK OF RENAL-CELL CANCER AMONG WOMEN USING DIURETICS IN THE UNITED-STATES

Use of prescription diuretics and incidence of renal cell cancer have increased in the United States in the past 25 years. Recent interview- based epidemiologic studies have reported an association between diure tic use and renal cell cancer risk. Our study evaluated this hypothesi s using, for the first time, medical records as the source of the info rmation on prescription diuretic use. Using medical records of women f rom a prepaid health plan, we identified 191 cases and 191 controls ma tched on age, membership duration, and membership at diagnosis. Diuret ics use and history of potential confounding factors were ascertained by a standardized review of the medical records of each subject, witho ut reference to case or control status. There was a strong and statist ically significant association between renal cell cancer and prescript ion diuretics (odds ratio [OR] adjusted for hypertension, smoking, and obesity = 2.9, 95 percent confidence interval [CI] = 1.7-4.7). Risk t ended to increase with dose, measured by number of prescriptions. Sinc e renal cancer can induce hypertension, which is treated by diuretics, and thereby confound the association with diuretics, we examined diur etic use 1 0 or more years prior to diagnosis when secondary hypertens ion would be unlikely. The OR for prescriptions 10 or more years befor e diagnosis was 3.5 (CI = 1.7-7.4). Our results support earlier report s of an excess risk of renal cell cancer among users of prescription d iuretics and indicate need for further study to evaluate this relation ship, especially due to the extensive use of diuretics and the increas ing incidence of this cancer.