ObjectivesTo investigate whether hypertension and the use of antihypertensive drugs are associated with mortality from cancer among women.DesignA prospective study of 11 075 women living in Utrecht, the Netherlands, aged 50–65 years at enrolment in a breast cancer screening project (DOM cohort). Women attended screening rounds between 1974 and 1985, during which blood pressure measurements were taken and information on drug use and smoking was ascertained. Since 1974 (median follow-up time 19 years) information on cause of death has been obtained from the patient's general practitioner. Hypertension was defined as a systolic blood pressure > 160 mmHg, a diastolic blood pressure > 95 mmHg, or current use of antihypertensive drugs. Cox regression analysis was used to investigate the association between hypertension (treated and untreated) and total and site-specific mortalities from cancer. The influences of systolic and diastolic blood pressures per 10 mmHg increase for women not using antihypertensive drugs were evaluated. Analyses were adjusted for age, smoking, and body mass index.ResultsIn total, 704 women died of cancer and 1633 women left the study area. Hypertensive women had a greater than normal (not statistically significant) total risk of mortality from cancer [hazard ratio (HR) 1.10, 95% confidence interval (CI) 0.93–1.31]. Risks for treated and untreated hypertensive women were similar. Cancer-site-specific analyses revealed a statistically significantly lower mortality from gastrointestinal cancers among untreated hypertensive women (HR 0.64, 95% CI 0.44–0.93), whereas mortality from lung cancer was more prevalent among these women (HR 2.50, 95% CI 1.37–4.59). Mortality from lymphatic and hematopoietic cancers for drug-treated hypertensive women was greater than normal (HR 2.11, 95% CI 1.04–4.28), as was mortality from cancers of the uterus, cervix, and ovary (HR 1.80, 95% CI 1.00–3.26).ConclusionThese results support the hypothesis that, if there is a link between blood pressure and cancer, it is likely to be positive and relatively small (+10%); and applies also to nondrug-treated women. The relation may apply for some types of cancer, but not for others.