Original articlePulse pressure and heart rate: Independent risk factors for cancer?
Introduction
Two decades ago, Dyer et al. [1] reported a relationship between blood pressure (BP) and cancer mortality, independent of age, smoking, and cholesterol. Since then, several prospective studies have examined this relationship but the results have been inconsistent. Some results showed a positive association 2, 3, some showed no association [4], and others even showed an inverse relationship among elderly subjects [5]. Some studies reported a positive relationship between BP and certain types of cancer 2, 3. The relationship between BP and cancer seems to vary according to the site of the cancer, the length of the follow-up and the presence of other risk factors [3]. Other studies suggest that this relationship may be an indirect result, due to the presence of confounding factors such as tobacco, alcohol intake and lack of physical activity, which may also be associated with high BP. A study conducted among middle-aged men who were randomly selected among patients from general practices in various British towns [6] showed that elevated BP is associated with an increased risk of cancer in current smokers only. This strengthens the hypothesis that the relationship between BP and cancer is the result of interactions with confounding factors.
The relationship between heart rate (HR) and cancer mortality was also examined. A majority of the findings reported a positive association between HR and cancer 7, 8. In 1981, Persky et al. [7] examined the relationship between HR and cancer in three epidemiological studies conducted in Chicago. Two of the three studies showed a positive association between HR and death from cancer. Because increased HR is associated with cigarette smoking and lack of physical activity 8, 9, it has been suggested that the relationship between HR and cancer mortality may be due to the relationships between cancer and lack of regular physical exercise or smoking. In several studies, data for physical activity were not available, making it impossible to evaluate this hypothesis. However, in other studies, after taking into account physical activity and other risk factors such as tobacco, the association between HR and cancer mortality persisted 8, 10. When examined together, these results suggest that mechanical hemodynamic factors such as BP and HR could be associated not only with CVD mortality but also with non-CVD mortality. However, it is unclear whether these associations depend on the presence of confounding factors or underlying diseases.
In the present study, we examined the role of HR and pulse pressure (PP = systolic-diastolic BP), the two main parameters of pulsatile hemodynamic stress, on the different types of cancer mortality in a large French cohort composed of 125,513 men. These associations were examined after taking into account physical activity, cigarette smoking, alcohol consumption and other confounding factors or underlying disease.
Section snippets
Population
Subjects were examined at the IPC Center (Centre d'Investigations Préventives et Clinques), a medical center which is subsidized by the French national health care system (Securité Sociale-CNAM) and which provides all working and retired individuals and their families with a free medical check-up every 5 years. It is one of the biggest medical centers of this kind in France, having carried out approximately 15,000 examinations per year from 1970 to 1978 and approximately 25,000 per year after
Results
Table 1 presents age-adjusted means according to HR groups. Age did not differ between the groups. SBP, DBP, PP, cholesterol, triglycerides, gamma-Gt levels and percentage of current smokers were positively associated with HR (P < 0.001). Physical activity and expiratory volume ratio were lower among accelerated HR groups (P < 0.001).
Tables 2 shows mortality rates for cancer according to HR. Mortality rates were higher in the HR3 group than in the HR1 group. Analysis according to different
Discussion
The main result of our study was that both HR and PP were positively associated with cancer mortality. After taking into account other risk factors such as tobacco, alcohol consumption and physical activity, the positive relationship between these two factors and cancer mortality remained significant. An important remark is that the risk related to HR acceleration was similar for cancer mortality and CVD mortality. The impact of PP was also equally important for both broncho-pulmonary cancer
Acknowledgements
This study was performed with the help of INSERM (Paris, France). We thank the Caisse National d'Assurance Maladie (CNAM) for supporting the study.
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