Associations of Age at Diagnosis of Breast Cancer with Incident Myocardial Infarction and Heart Failure: a Prospective Cohort Study

Background The associations of age at breast cancer onset with incident myocardial infarction (MI) and heart failure (HF) remain unexamined. Addressing this problem could promote understanding of the cardiovascular impact of breast cancer. Methods Data were from the UK Biobank. Information on diagnosis of breast cancer, MI and HF were collected at baseline and follow-ups (median=12.8 years). Propensity score matching method and Cox proportional hazards models were employed. Results A total of 251,277 female participants (mean age: 56.8±8.0 years), of whom 16,241 had breast cancer, were included. Among participants with breast cancer, younger onset age (per 10-year decrease) was significantly associated with elevated risks of MI (HR=1.36, 95%CI: 1.19 to 1.56, P <0.001) and HF (HR=1.31, 95% CI: 1.18 to 1.46, P <0.001). After propensity score matching, breast cancer patients with younger onset age had significantly higher risks of MI and HF than healthy controls. Conclusion Younger onset age of breast cancer was associated with higher risks of incident MI and HF, underscoring the necessity to pay additional attention to the cardiovascular health of breast cancer patients diagnosed at younger age to conduct timely intervention to attenuate the subsequent risks of incident cardiovascular diseases. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by grants from the National Natural Science Foundation of China (82373665 & 81974490), the Nonprofit Central Research Institute Fund of Chinese Academy of Medical Sciences (2021-RC330-001), and the 2022 China Medical Board-open competition research grant (22-466). All authors had no conflict of interest. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The UK Biobank has received ethical consent from the North West Multi-centre Research Ethics Committee (MREC) (299116). Written informed consent was obtained from all participants. This research was done without participants involvement. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data used for analysis in this study are available from the UK Biobank project site, subject to registration and application processes. Further details can be found at https://www.ukbiobank.ac.uk.