Statins may protect against post-radiotherapy stroke
Statins may protect patients against stroke after radiotherapy exposure for head, neck, or thoracic cancer, according to an observational study from Canada.
“[S]tatin use was associated with a significant 32 percent reduction in stroke, and a strong trend toward reducing the composite outcome of cardiovascular (CV) and cerebrovascular events,” said the researchers.
“Our study demonstrated that statin therapy could be favourable even with the competing risks of cancer and cancer-related mortality in patients who received radiation therapy,” said study author Assistant Professor Negareh Mousavi from McGill University Health Centre, Montreal, Quebec, Canada.
This retrospective cohort study – which used information from health insurance databases in Quebec, Canada – included 5,718 patients aged >65 years with CV disease (CVD)* who underwent radiotherapy for head, neck, or thoracic cancer. Of these, 4,166 patients were on statins (mean age 75 years, 43 percent female), initiated 1 year pre-radiotherapy.
CV risk factors such as coronary artery disease (CAD), prior myocardial infarction (MI), diabetes, dyslipidaemia, and hypertension were more common among statin users vs nonusers (p<0.0001), as was the use of concomitant medications such as aspirin, clopidogrel, β-blockers, angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers (p<0.0001 for all), and warfarin (p=0.02). There was no difference in the use of additional chemotherapy between statin users and nonusers (p=0.42).
Post-radiotherapy, the incidence of CVD (fatal or nonfatal MI) or cerebrovascular events (transient ischaemic attack [TIA], fatal or nonfatal stroke, or carotid revascularization) was numerically higher among statin nonusers than users (10.31 percent vs 9.03 percent) over a mean follow-up period of 534 and 594 days among statin nonusers and users, respectively. [J Am Heart Assoc 2019;8:e005996]
After adjusting for multiple factors**, there was a reduced risk of post-radiotherapy CVD and cerebrovascular events among statin users compared with nonusers, though the findings were not statistically significant (adjusted hazard ratio [adjHR], 0.85, 95 percent confidence interval [CI], 0.69–1.04; p=0.1068).
However, when looking solely at the risk of post-radiotherapy stroke, statin users had a significantly reduced risk compared with nonusers (adjHR, 0.68, 95 percent CI, 0.48–0.98; p=0.0368).
All-cause mortality was also significantly reduced among statin users vs nonusers (p<0.0001).
The lack of significant impact of statins on the risk of fatal and nonfatal CVD and cerebrovascular disease could be due to the high-risk population of patients, said the researchers, with the difference in comorbidities and medication use at baseline between statin users and nonusers potentially affecting the findings.
There was no significant difference in the incidence of hepatitis, transaminitis, myositis, or myalgia between groups, though sleep disorders and myopathy were more common among statin users.
“There is a growing body of evidence showing increasing burden of vascular events post-radiotherapy to the thorax, head, or neck,” said Mousavi and co-authors.
With the issues complicating treatment of CVDs such as radiation-induced atherosclerosis (RIA) in this population, [J Vasc Surg 2012;56:1143-1152; Arch Otolaryngol Head Neck Surg 2000;126:517-521] “primary and secondary preventive therapies for RIA” are much needed, they said.
Among patients who already meet the criteria for receipt of statin therapy, the study results reinforce the necessity of continuation of these medications following radiotherapy, said the researchers. Clinical trials will hopefully elucidate the role of statins following radiotherapy in those who do not yet have an indication, they added.