The objective of this study was to determine the sitespecific cancer incidence of hypertensive patients and examine the effect of blood pressure-related variables on the risk of cancers with elevated incidence among the hypertensive patients. A record linkage study of Hypertension Register of the North Karelia Project and the Finnish Cancer Registry was conducted. The mean follow-up time was 16 years. A total of 20 529 hypertensive patients were studied. Main outcome measures were standardised incidence ratios and hazard ratios. The overall cancer incidence was close to that of the general population for both men and women. The incidence rate for the kidney cancer was significantly increased in hypertensive patients (standardised incidence ratio 1.34, 95% confidence interval (CI) 1.11-1.60), as well as incidence rates for cancers of pancreas (1.26, 1.02-1.54), and endometrium (1.22, 1.01-1.44) in hypertensive women. The incidence of lung cancer was significantly decreased (0.86, 0.77-0.95). The incidence of liver cancer was elevated with borderline significance (1.36, 0.99-1.82). In Cox regression models, the use of antihypertensive drugs at baseline was a significant predictor of kidney (hazard ratio for use of antihypertensive drugs 1.89, 95% CI 0.96-3.75) and pancreatic cancer (1.78, 0.99-3.22) in women but not in men. The incidence of endometrial cancer or liver cancer was not related to blood pressure levels or the use of antihypertensive drugs. In women, obesity was a significant predictor of cancers of the endometrium, kidney and liver. In conclusion, increased occurrence of some cancer types among hypertensive patients seem to be partly explained by obesity and the use of antihypertensive drugs.

Few studies have suggested that elevated blood pressure might be associated with increased risk of lung cancer and that this association might vary according to smoking status. The aim of this study was to assess the effect of blood pressure and its possible interaction with smoking on lung cancer incidence in hypertensive patients. Lung cancer incidence was determined for 7,908 men enrolled in the hypertension register of the North Karelia Project between 1972 and 1988 by record linkage to the nationwide Finnish Cancer Registry. In a Cox regression model, both systolic and diastolic blood pressures were significant predictors of lung cancer, with a 10% increase in risk per 10-mmHg increment in blood pressure. In smokers, the age-adjusted hazard ratio associated with a 10-mmHg increment in diastolic blood pressure was 1.17 (95% confidence interval: 1.05, 1.29), and in nonsmokers it was 0.98 (95% confidence interval: 0.80, 1.16). For systolic blood pressure, these hazard ratios were 1.11 (95% confidence interval: 1.05, 1.17) for smokers and 1.04 (95% confidence interval: 0.95, 1.14) for nonsmokers. These findings suggest that high blood pressure levels are associated with increased risk of lung cancer in smoking, hypertensive men.

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...

Abstract-Cancer incidence of 20 529 hypertensive patients included in the community-based hypertension register of the North Karelia Project was determined. A total of 2511 incident cancer cases were obtained among the patients in record linkage with the nationwide Finnish Cancer Registry during the mean follow-up time of 16 years. The age-adjusted incidence rates per 100 000 person-years were 248.4 for men and 171.7 for women, which correspond to that of the general population in the area. The Cox regression model was used to analyze the effect of hypertension-related variables on cancer incidence. In men, the diastolic blood pressure was associated with an increased cancer risk but only in those who smoked Ͼ10 cigarettes per day. positive association between high blood pressure and cancer mortality in a cohort of 1233 Chicago Gas Company male employees. The relative risk was 3-fold if the systolic blood pressure (SBP) was Ͼ160 mm Hg and 2-fold if the diastolic blood pressure (DBP) was Ͼ95 mm Hg, adjusted for smoking, cholesterol, and age, and it could not be explained by the use of antihypertensive drugs. After that study, the relationship between hypertension and cancer has been examined in many cohort studies, 2-13 with varying methodology and magnitude, but the results remain controversial. In many of these studies that measured cancer mortality, a positive association between high blood pressure and subsequent all-site cancer mortality could be observed, 2-5,10,11,13 whereas in 2 studies, the association was inverse in the elderly population. 8,9 The few cohort studies that examined the cancer incidence also gave inconsistent results. 6,7,12 Some studies have also shown that the use of some types of antihypertensive drugs, particularly calcium channel blockers, might be associated with increased risk of cancer, 14,15 but the issue remains unproven. 16,17 The aim of this study was to describe the cancer incidence of hypertensive patients from North Karelia, Finland, and to investigate how the severity of hypertension affects the cancer incidence. This was done by record linkage of the community-based hypertension register of the North Karelia project and the cancer incidence data of the Finnish Cancer Registry. MethodsThe study cohort consisted of 20 886 hypertensive patients who were included in the community-based hypertension register of the North Karelia project. The details of the register are described elsewhere. 18 The register was run within the primary healthcare system in North Karelia province in 1972 to 1988 as part of the North Karelia Project. 19 All subjects who either were on antihypertensive drug treatment because of earlier diagnosis of hypertension or who had elevated blood pressure in 3 subsequent measurements were eligible to be registered. The blood pressure criteria were as follows: 150 and/or 90 mm Hg (Ͻ29 years), 160 and/or 95 mm Hg (30 to 64 years), and 170 and/or 95 mm Hg (Ͼ65 years). Blood pressure measurements were performed by local nurses and physicians who had received specia...