¹Department of Medicine, Epidemiology Division, University of California, Irvine, Irvine, CA, USA

Correspondence: Dr JA Largent, Department of Medicine, Epidemiology Division, University of California, Irvine, 224 Irvine Hall, Irvine, CA 92697-7555, USA. E-mail: jlargent@uci.edu

Received 31 January 2006; Revised 20 June 2006; Accepted 21 June 2006; Published online 3 August 2006.

Abstract

It is unclear whether hypertension and antihypertensive medication use are associated with breast cancer. In order to examine these associations, we conducted a case–control study among women aged 50–75 years. Breast cancer cases were ascertained via a population-based cancer registry (n=523) and controls were ascertained via random-digit-dialing (n=131). Participants completed a self-administered questionnaire which queried history of hypertension, antihypertensive medication use and risk factors. Unconditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (CI), adjusted for age, body mass index (BMI), diabetes, smoking, alcohol use, menopausal status, family history of breast or ovarian cancer, age at first full-term pregnancy and education. History of treated hypertension was associated with significant increased risk of breast cancer (OR, 1.77; 95% CI, 1.04–3.03) and this association appeared only in women with BMI 25 kg/m² (OR, 2.30; 95% CI, 1.12–4.71). Diuretic use was also associated with elevated breast cancer risk (OR, 1.79; 95% CI, 1.07–3.01). The risk associated with diuretic use increased with duration of use (P for trend, <0.01). Use of other blood pressure medications was not found to be associated with breast cancer risk. These results support a positive association between treated hypertension, diuretic use and breast cancer risk among women aged 50–75 years.