Is cancer related to hypertension or to its treatment?

Three questions related to cancer and blood pressure are discussed. (i) Is cancer related in some way to hypertension, or to blood pressure? Several studies show a relation of blood pressure and cancer in populations. However, our own experience, based on a cohort of 15,411 subjects with BP measured in the 1970s and with 1,392 fatal cancers since, shows no relation of cancer risk and diastolic pressure. Nor were cancer numbers (n=72) observed in the 1,078 untreated hypertensives of the Glasgow Blood Pressure Clinic different from those expected (n=71.2) in a control population matched for age, sex and smoking habit. (ii) Do antihypertensive drugs promote cancer? Atenolol and calcium channel blockers have been suspected of this, but evidence of larger studies, including two of our own, is negative: relative risk for cancer in our patients taking CCB was 1.02 (CI 0.82-1.27). (iii) Do antihypertensive drugs protect against cancer? A study of ours based on the Glasgow Clinic raises this possibility: relative risk for incident cancer amongst 1,559 patients taking ACE inhibitor was 0.72 (CI 0.55-0.92).