A review of 33 clinical studies showed that antihypertensive drugs did not have a consistent association with cancer risk.
Patients treated with any of five different classes of antihypertensive drugs had essentially the same cancer risk as those receiving placebo. Comparisons of each antihypertensive class against all the others showed no association with an increased risk of cancer, save for calcium channel blockers (CCBs), which had only a modestly higher risk versus the other drug classes (HR 1.06, 95% CI 1.01-1.11).
The data do not conclude the issue, since some comparisons had insufficient data to exclude the possibility of excess cancer risk, reported Kazem Rahimi, DM, of the University of Oxford in England, and colleagues in Lancet Oncology.
“Our study has addressed an ongoing controversy about the safety of blood pressure-lowering medication with respect to cancer risk, using the largest sample of individual-level randomized evidence on blood pressure-lowering treatment to date, to our knowledge,” they wrote. “The main implication of our study is that patients using antihypertensive medication should continue to take their medications because concerns about increased cancer risk seem to be unfounded.”
The author of an accompanying commentary noted that the findings could have been due to chance. The number of trials per drug class varied greatly, and small sample sizes were used in analyses by type of cancer.
“Taken together, these limitations raise a more fundamental question about how the findings of randomised controlled trials should be interpreted,” wrote Laurent Azoulay, PhD, of McGill University in Montreal.
Randomised trials are the “gold standard” for assessing drug efficacy, but are not typically designed to assess safety, he continued. This is especially important for outcomes like cancer, which have a delayed onset. Since the median follow-up was only 4.2 years , “a potential association between cancer and the long-term use of antihypertensive drugs cannot be ruled out.”
“Such analyses are necessary to understand the short-term effects of these drugs on cancer incidence,” Azoulay concluded. “However, moving forward, these studies will need to be complemented with well-designed, real-world studies in heterogeneous patient populations who are followed up for extended periods of time to fully understand their carcinogenic potential.”
Several meta-analyses have yielded conflicting evidence, Rahimi and colleagues stated. The Blood Pressure Lowering Treatment Trialists’ Collaboration (BPLTTC) is the world’s largest individual patient-level data on blood pressure-lowering trials, and data from this formed the basis for the meta-analysis.
The authors identified 33 trials for inclusion in the meta-analysis, which comprised 260 447 patients with available data on cancer outcomes. CCBs were the antihypertensive class most commonly represented in the trials (n=19), followed by ACE inhibitors (15), angiotensin-receptor blockers (ARBs, 11), thiazide diuretics (six), and beta-blockers (five). Median follow-up ranged from 4 to 5 years across the trials, grouped by drug class.
Patient age ranged between 64 and 68 by drug class, and pretreatment systolic blood pressure ranged from 147mm Hg (ACE inhibitors) to 166mm Hg (beta-blockers).
Across the five classes of antihypertensive drugs, individual comparisons for cancer risk versus the other drug classes yielded only a maximum hazard ratio of 1.06 for CCBs.
“We found no consistent evidence that antihypertensive medication use had any effect on cancer risk,” the authors stated.
Source: MedPage Today
Journal information 1: Copland E, et al “Antihypertensive treatment and risk of cancer: An individual participant data meta-analysis” Lancet Oncol 2021; DOI: 10.1016/S1470-2045(21)00033-4.
Journal information 2: Azoulay L “Elucidating the association between antihypertensive drugs and cancer: A need for real-world studies” Lancet Oncol 2021; DOI: 10.1016/S1470-2045(21)00085-1.
