INTERNATIONAL RENAL-CELL CANCER STUDY .8. ROLE OF DIURETICS, OTHER ANTIHYPERTENSIVE MEDICATIONS AND HYPERTENSION

Risk of renal-cell cancer in relation to use of diuretics, other anti- hypertensive medications and hypertension was assessed in a multi-cent er, population-based, case-control study conducted in Australia, Denma rk, Germany, Sweden and the United States, using a shared protocol and questionnaire. A total of 1,732 histologically confirmed cases and 2, 309 controls, frequency-matched to cases by age and sex, were intervie wed. The association between renal-cell cancer and the drugs was estim ated by relative risks (RRs) and 95% confidence intervals (Cls). Risks were increased among users of diuretics and other anti-hypertensive m edications. After adjustment for hypertension, risk for diuretics was reduced to unity, except among long-term (15+ years) users. Risk for u se of non-diuretic anti-hypertensive drugs remained significantly elev ated and increased further with duration of use. Overall risk was not enhanced when both classes of medications were used. Excess risk was n ot restricted to any specific type of diuretic or anti-hypertensive dr ug and no trend was observed with estimated lifetime consumption of an y particular type of product. The RR for hypertension after adjustment for diuretics and other anti-hypertensive medications was 1.4 (95% CI = 1.2-1.7), although among non-users of any anti-hypertensive medicat ions, there was little excess risk associated with a history of hypert ension. Exclusion of drug use that first occurred within 5 years of ca ncer diagnosis or interview did not alter the associations. Our findin gs suggest small effects on renal-cell cancer risk associated with hyp ertension and use of diuretics and other anti-hypertensive medications . However, because of potential misclassifications of these highly cor related variables, it is difficult to distinguish the effect of treatm ent from its indication, hypertension. (C) 1995 Wiley-Liss, Inc.