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Observational Study
. 2019 Jan;42(1):93-100.
doi: 10.1002/clc.23114. Epub 2018 Dec 7.

Are aromatase inhibitors associated with higher myocardial infarction risk in breast cancer patients? A Medicare population-based study

Sailaja Kamaraju  1   2 , Yushu Shi  1 , Elizabeth Smith  1 , Ann B Nattinger  1 , Purushottam Laud  1   3 , Joan Neuner  1   4
Affiliations
Observational Study

Are aromatase inhibitors associated with higher myocardial infarction risk in breast cancer patients? A Medicare population-based study

Sailaja Kamaraju et al. Clin Cardiol. 2019 Jan.

Abstract

Background: Theoretically, the estrogen deprivation induced by aromatase inhibitors (AIs) might cause ischemic heart disease, but empiric studies have shown mixed results. We aimed to compare AIs and tamoxifen with regard to cardiovascular events among older breast cancer patients outside of clinical trials. We hypothesized that AIs increase the risk of myocardial infarction.

Methods: We identified women age ≥67 years diagnosed with breast cancer from June 30, 2006 to June 1, 2008 in the surveillance, epidemiology, and end results (SEER)-Medicare database, treated with either tamoxifen or an AI, and followed through December 31, 2012. To compare myocardial infarction (MI) risk for the treatment groups of AIs vs tamoxifen, we developed and assigned stabilized probability of treatment weights and used the Fine and Gray model for time to MI with death not related to MI as a competing risk.

Results: Of the cohort of 5648 women, 4690 were treated with AIs and 958 with tamoxifen; a total of 251 patients developed MI, and 22 patients died of MI during the study period while 476 died of other causes. The hazard for MI was not significantly different between AI vs tamoxifen groups (HR = 1.01, 95% CI 0.72-1.42), after adjusting for the following known MI risk factors at the start of adjuvant therapy: diabetes, ischemic heart disease, congestive heart failure, MI, and peripheral vascular disease.

Conclusions: In this SEER-Medicare-based population study, there were no significant differences in the risk of MI between AI and tamoxifen users after adjustment for known risk factors.

Keywords: adjuvant hormonal therapy; and cardiotoxicity; aromatase inhibitors; breast cancer; tamoxifen.

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Conflict of interest statement

Author contributions

Sailaja Kamaraju is contributed in conceptualization, coordination of methodology, data collection, writing the original draft, and editing/review and writing of the final manuscript. Yushu Shi is contributed in data collection, formal analysis, writing the original manuscript, reviewing the final manuscript. Elizabeth Smith is contributed in methodology, and statistical analysis, reviewing the final draft. Ann B. Nattinger is contributed in conceptualization, and review and editing of the final manuscript. Purushottam Laud is contributed in design of methodology, statistical analysis, data analysis, review and editing of the final manuscript. Joan Neuner is contributed in conceptualization, data collection, methodology, an overview of the statistical analysis, overall supervision, and writing ‐review, and editing of the manuscript.

Figures

Figure 1
Figure 1
Aromatase inhibitor vs tamoxifen therapy confidence intervals for Hazard of myocardial infarction ratios for selected variables
Figure 2
Figure 2
Hazard ratios for MI by hormone therapy, AI vs tamoxifen, in selected sub‐groups
See this image and copyright information in PMC

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