Background: This paper examines the relationship between blood pressure and cancer mortality.
Methods: A prospective study of 7735 middle-aged men drawn at random from one general practice in each of 24 British towns.
Results: During a mean follow-up period of 12.75 years there were 351 deaths from cancers. The relationship between blood pressure and cancer differed with respect to follow-up period. In the first 5 years of follow-up, a significant inverse relationship was seen between systolic (SBP) and diastolic blood pressure (DBP) and cancer mortality even after adjustment for age, smoking, social class, physical activity, alcohol intake, body mass index, diabetes, pre-existing ischaemic heart disease, use of antihypertensive drugs, cholesterol, heart rate and serum albumin. In the subsequent follow-up period (5.1-12.75 years) a significant positive association was seen between SBP (but not DBP) and risk of cancer mortality, even after adjustment for the other risk factors. Men in the top fifth of SBP ( > or = 161 mmHg) showed over a 50% increase in risk of cancer mortality compared to men in the bottom quintile (RR = 1.56 95% CI 95% CI: 1.04-2.38). This positive relationship between SBP and cancer was seen only in current cigarette smokers. Use of antihypertensive drugs was not associated with cancer mortality.
Conclusion: The association of elevated SBP with increased risk of cancer mortality seen only in current smokers warrants the search for factors which affect SBP, interact with smoking and are potentially carcinogenic.