Breast Cancer Long-term Outcomes on Cardiac Functioning: a Longitudinal Study

Rationale: In addition to surgery, effective breast cancer (BC) treatment typically requires chemotherapy, radiotherapy, or both. However, it is still unclear whether patients with BC are at increased risk of long-term cardiac dysfunction due to the adverse effects of these therapies. In a cross-sectional study in primary care, a comparison on cardiac dysfunction between 350 BC survivors and 350 age- and general practitioner (GP)- matched controls without cancer was made. In that study, BC survivors were at increased risk of mild systolic cardiac dysfunction (left ventricle ejection fraction (LVEF)\< 54%). By contrast, there was no significant difference in an LVEF \< 50% or in diastolic dysfunction. To date it remains uncertain whether the mild or subclinical dysfunction we observed predicts further cardiac deterioration. Consequently, the translation of these results into guidelines for the daily practice of the GP is unclear.

Objective: The aim of the here proposed study is to clarify whether cardiac function in survivors of BC should be monitored by GPs, by assessing whether an unselected population of long-term BC survivors is at increased risk of developing cardiac dysfunction, whether in this group at-risk subgroups exists, and what factors are associated with the highest risk.

Study design: A new assessment of cardiac function among women included in the BLOC-I study. This produces a longitudinal matched cohort design consisting of two cohorts in primary care.

Study population: Survivors of BC, diagnosed ≥11 years ago who received chemotherapy and/or radiotherapy, and a matched reference population with no history of cancer. All participants participated in the Breast cancer Long-term Outcome of Cardiac function (BLOC-I) study.

Main study parameters/endpoints: Left ventricular systolic dysfunction. Systolic cardiac dysfunction is defined as a LVEF \<54/50/45%.