Relation between drug treatment and cancer in hypertensives in the Swedish Trial in Old Patients with Hypertension 2: a 5-year, prospective, randomised, controlled trial

Abstract

Background: Is cancer related to hypertension and blood pressure? Do antihypertensive drugs promote cancer? Do antihypertensive drugs protect against cancer? We previously analysed the frequency of cardiovascular mortality and morbidity in elderly people who participated in the Swedish Trial in Old Patients with Hypertension 2 (STOP-Hypertension-2). We have also looked at the frequency of cancer in these patients.

Methods: We randomly assigned 6614 elderly patients with hypertension (mean age 76 years, median time of follow-up 5.3 years) to one of three treatment strategies: conventional drugs (diuretics or b-blockers), calcium antagonists, or ACE inhibitors. We matched the patients to the Swedish Cancer Registry and compared our findings with expected values based on age, sex, and calendar-year-specific reference frequencies for the general Swedish population. We also compared the number of cancers between the three treatment groups.

Findings: At baseline, 607 (9%) patients had previous malignant disease. Diagnoses were closely similar to the distribution of cancer types that might be seen in elderly patients. During follow-up, there were 625 new cases of cancer in 590 patients. The frequency of cancer did not differ significantly between the treatment strategies, including all cancers and those at individual sites. The standardised incidence ratios (SIRs) for all cancers were also close to unity: 0.92 (95% CI 0.80-1.06) for conventional drugs, 0.96 (0.83-1.10) for calcium antagonists, and 0.99 (0.86-1.13) for ACE inhibitors.

Interpretations: No difference in cancer risk was seen between patients randomly assigned to conventional drugs, calcium antagonists, or ACE inhibitors. Thus, the general message to the practising physician is that more attention should be given to getting the blood pressure down than to the risk of cancer.