Stroke, Cardiac Ischaemia Risk Comparable For Postmenopausal Breast Cancer AI And Taxmoifen Users

The risk of cardiovascular events has been characterised in postmenopausal breast cancer patients using aromatase inhibitors and/or tamoxifen

medwireNews: Among postmenopausal, hormone receptor-positive breast cancer patients, aromatase inhibitor (AI) therapy has a comparable risk of myocardial infarction and stroke to that of tamoxifen treatment, US researchers have found.

Over 72,886 person–years in 13,273 women with postmenopausal breast cancer attending community hospitals in California, 3711 cardiovascular disease (CVD) events were reported.

After adjusting for CVD medication use, ethnicity, age at breast cancer diagnosis, disease stage and other characteristics, there was no significant difference in the risk of stroke or cardiac ischaemia, defined as myocardial infarction or angina, between AI users and tamoxifen users.

“These results provide reassurance that AIS may not increase [the] risk of the most fatal CVDs”, say Reina Haque, from Kaiser Permanente Southern California in Pasadena, and co-authors in JAMA Oncology.

However, the analysis did detect an “unexpected” increased risk of other CVD events with AI therapy.

The team identified a “somewhat higher risk” of heart failure and cardiomyopathy in women using AIs (adjusted hazard ratio [HR]=1.10) or AIs plus tamoxifen (HR=1.27) than those given tamoxifen alone, although these differences did not reach significance.

Moreover, the risk of other CVD events – defined as dysrhythmia, arrhythmia and pericarditis – was significantly higher for patients using AIs or AIs and tamoxifen than tamoxifen alone, with adjusted HRs of 1.29 and 1.26, respectively.

“The association[s] between AI use and other cardiac events (dysrhythmia, valvular dysfunction, and pericarditis) and heart failure/cardiomyopathy were unexpected and require further study”, the authors write.

“Based on our literature review, to our knowledge, our analysis provides the first comprehensive assessment of AI influence that accounted for CVD risk factors and cardiovascular medication use.”

They add that adjusting for body mass index did not impact this increased risk of other CVD events and that the literature review failed to identify a potential mechanism linking oestrogen reduction by AIs with these CVD events.

Reference

Haque R, Shi J, Schottinger JE, et al. Cardiovascular disease after aromatase inhibitor use. JAMA Oncol 2015; Advance online publication 21 April. doi:10.1001/jamaoncol.2016.0429

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