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MI, HF, and Oncologic Outcomes in Breast Cancer Survivors
Quick Takes
- Breast cancer survivors who develop HF or MI face a four-fold increased risk of cancer-related death.
- HF shows stronger associations with adverse oncologic outcomes compared to MI alone.
- Findings underscore the need for integrated CV monitoring in cancer survivors, while recognizing that the association may not be causal.
Study Questions:
Does the development of cardiovascular (CV) events, specifically myocardial infarction (MI) or heart failure (HF), in breast cancer survivors influence their oncologic outcomes?
Methods:
This population-based cohort study used Ontario administrative health data to analyze breast cancer survivors diagnosed between 2007 and 2015. Using a landmark analysis design, patients were followed from 2 years post-diagnosis to ensure completion of initial cancer therapy, excluding those with pre-existing CV disease or advanced cancer at baseline. The exposure was defined as the first occurrence of MI or HF after the landmark date, with outcomes measured as cancer-specific mortality, new nonbreast malignancy diagnosis, and initiation of new chemotherapy. Cause-specific hazard regression models were applied, adjusting for demographic and clinical factors, with MI/HF modeled as a time-dependent variable.
Results:
The study analyzed 30,694 breast cancer survivors with a median age of 60 years, following them from a landmark point of 2 years after their cancer diagnosis. During follow-up, 1,346 women developed incident MI or HF at a median of 3.9 years after the landmark date. In the overall cohort, the 5-year cumulative incidence was 5.9% for cancer death, 4.3% for nonbreast malignancy, and 25.7% for new chemotherapy initiation. After adjusting for baseline characteristics, the development of incident MI/HF was independently associated with a nearly four-fold higher risk of cancer mortality (hazard ratio [HR], 3.94; 95% confidence interval [CI], 3.38-4.59). These patients also faced a 39% higher risk of being diagnosed with a nonbreast malignancy (HR, 1.39; 95% CI, 1.06-1.82) and a 25% increased likelihood of requiring new chemotherapy (HR, 1.25; 95% CI, 1.02-1.53). When analyzing the CV events separately, HF demonstrated notably stronger associations with adverse outcomes compared to MI alone. Specifically, HF was associated with a 4.5-fold increased risk of cancer death (HR, 4.50; 95% CI, 3.84-5.29), while MI alone showed a more modest but still significant doubling of risk (HR, 2.14; 95% CI, 1.32-3.45).
Conclusions:
Incident MI or HF in breast cancer survivors is associated with higher risks of cancer mortality, secondary malignancies, and subsequent chemotherapy, emphasizing the prognostic impact of CV events on oncologic outcomes.
Perspective:
This study reveals important associations between CV events and adverse cancer outcomes in breast cancer survivors. While the authors appropriately highlight biological mechanisms and the need for CV monitoring, several additional perspectives merit consideration. From a health systems perspective, these findings challenge current care models that often separate cardiology and oncology services, suggesting the need for integrated follow-up protocols. The universal health care setting of Ontario provides a unique lens but raises questions about how these associations might differ in systems with varying access to care. The study also raises intriguing questions about whether CV medications might modify cancer outcomes through effects on shared pathways. Future clinical trials might benefit from including cross-disciplinary endpoints, while developing risk prediction tools that integrate both CV and cancer parameters. These perspectives suggest the need for a more integrated approach to survivor care, encompassing both biological mechanisms and health care delivery innovations.
Clinical Topics: Heart Failure and Cardiomyopathies, Acute Heart Failure, Cardio-Oncology
Keywords: Breast Neoplasms, Cardio-oncology, Heart Failure, Myocardial Infarction
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