Incidence of breast cancer among postmenopausal, hypertensive women

Abstract

Elevated blood pressure has been proposed to be a risk factor for breast cancer but the results remain controversial. In this study, the incidence of breast cancer among 9,112 postmenopausal, hypertensive women included in the community-based hypertension register of the North Karelia project was assessed through the Finnish Cancer Registry. The mean follow-up time was 27 years. The incidence of breast cancer in hypertensive women in our cohort was similar to the age and period specific population-based rates for Eastern Finland [the standardised incidence ratio 0.96 (95% confidence interval 0.86-1.05)]. In the Cox regression analysis, there was no association between blood pressure levels, or use of antihypertensive (AH) drugs, and breast cancer incidence, when all women were considered. There was a statistically significant interaction of the use of AH drugs at baseline and the diastolic blood pressure (DBP). Among women who were not using AH drugs at baseline, the DBP level was positively associated with the subsequent risk of breast cancer (hazard ratio 1.26/10 mm Hg, 95% confidence interval 1.06-1.46). In women with AH drugs at baseline, the DBP had an opposite effect of borderline significance (hazard ratio 0.90/10 mm Hg, 95% confidence interval 0.78-1.01). In conclusion, breast cancer incidence among postmenopausal hypertensive patients in general does not differ from that of general population. Elevated DBP levels may be associated with an increased breast cancer risk among nonpharmacologically treated women. ' 2007 Wiley-Liss, Inc.Key words: breast cancer; hypertension; postmenopausal; antihypertensive drugs In 1974, three subsequent articles showed increased risk of breast cancer in women using reserpine, a drug commonly used to treat hypertension that time.1-3 The question was raised, whether it might be the hypertension per se, and not the drug, that caused this elevation of risk. In the same year, one study reported no association between self reported hypertension and breast cancer mortality 4 whereas another study showed that among postmenopausal women the presence of hypertension was associated with 40% increase in breast cancer incidence.5 However, the results of the latter study were not adjusted for the obesity. Subsequently, three prospective studies have assessed the effect of elevated blood pressure on breast cancer risk. T€ ornberg et al. 6 showed a small but statistically significant increase in risk, both in pre-and postmenopausal women, whereas Manjer et al. 7 reported no association in either of these groups. Peeters at al. reported a modest association, which became nonsignificant after adjustment for other confounders.8 Also results from the case-control studies have been controversial. [9][10][11][12][13][14] Later, the use of calcium channel blockers has been associated with increased cancer risk, 15 and especially breast cancer risk, 15 but these findings have not been confirmed. 16,17 In this study, we assessed the effects of blood pressure levels on the incidence of breast canc...

Blood Pressure and Risk of Cancer Incidence and Mortality in the Metabolic Syndrome and Cancer Project

“…30 Inconsistent associations have also been found for cancer of the colon, breast, lung, and prostate. 8,[31][32][33][34] A link between BP and cancer, as found in our study, could speculatively be mediated via proliferative abnormalities in vascular smooth muscle cells. 35 However, BP might be a proxy for another cancer risk factor, or the association between BP and cancer risk may be confounded by factors such as central obesity, which we might not have accurately adjusted for by the use of BMI.…”

Hypertension and the Risk of Breast Cancer in Chilean Women: a Case-control Study

“…Some studies report a weak-to-moderate association between HT and BC in postmenopausal women (Soler et al, 1999;Largent et al, 2006;Kabat et al, 2009;Rosato et al, 2011), but this is not consistent with other studies (Lindgren et al, 2007;Agnoli et al, 2009;Bjorge et al, 2010;Reeves et al, 2012). Some authors suggest that the observed association between HT and BC is confounded by obesity, which is a risk factor for both postmenopausal BC and HT (Franceschi et al, 1990;La Vecchia et al, 1997).…”

“…This association has been found in women whose anti-HT drugs include diuretics, and a possible pathway for BC development might be an increase in insulin resistance (Li et al, 2003;Largent et al, 2006). However, in a cohort study with a mean DOI:http://dx.doi.org/10.7314/APJCP.2012.13.11.5829 Hypertension and Breast Cancer Risk in Chile -a Case-control follow-up of 27 years, only a small effect was found in women who had high diastolic blood pressure and were not using anti-HT drugs at baseline (Lindgren et al, 2007). In addition, pooled analysis of 5 case-control studies did not find an association between anti-HT drugs and BC risk (Grossman et al, 2002).…”

New concepts of breast cancer aetiology

“…Researchers found no difference in breast cancer risk between women who took antihypertensive drugs and women who did not (7). But women with higher than normal diastolic blood pressure, who were not taking medicine to control it, were found to have a higher risk of breast cancer (8).…”