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 diuretic use and renal cell cancer risk. Our study evaluated this hypothesis using, for the first time, medical records as the source of the information on prescription diuretic use. Using medical records of women from a prepaid health plan, we identified 191 cases and 191 controls matched on age, membership duration, and membership at diagnosis. Diuretics use and history of potential confounding factors were ascertained by a standardized review of the medical records of each subject, without reference to case or control status. There was a strong and statistically significant association between renal cell cancer and prescription diuretics (odds ratio [OR] adjusted for hypertension, smoking, and obesity = 2.9, 95 percent confidence interval [CI] = 1.7-4.7). Risk tended to increase with dose, measured by number of prescriptions. Since renal cancer can induce hypertension, which is treated by diuretics, and thereby confound the association with diuretics, we examined diuretic use 1 0 or more years prior to diagnosis when secondary hypertension would be unlikely. The OR for prescriptions 10 or more years before diagnosis was 3.5 (CI = 1.7-7.4). Our results support earlier reports of an excess risk of renal cell cancer among users of prescription diuretics and indicate need for further study to evaluate this relationship, especially due to the extensive use of diuretics and the increasing incidence of this cancer.