The Cardiovascular Effects of Breast Cancer Radiation Therapy
Authors: Chhina Jashnoor , Chau Oi Wai , Navarro Jose , Sendzik Hannah , Frisbee Jefferson , Frisbee Stephanie 
Published: May 2022

Breast Cancer (BC) is the most common malignancy affecting women worldwide [1]. Adjuvant radiation therapy (RT) of the breast plays a vital role in BC treatment and has been shown to improve overall survival [2]. Due to increased survivorship, the cardiac sequelae that develop due to BC treatments have become more apparent. Radiation therapy, a common BC treatment, exposes the heart to radiation due to its presence in the irradiation field. Although modern RT techniques aim to reduce cardiac radiation exposure, research suggests the persistence of cardiac damage. This scoping review aims to establish the types of cardiovascular disease (CVD) that manifest post‐RT, and create a timeline for early radiation‐induced cardiotoxicity detection and surveillance.

A scoping review was conducted utilizing the methodology of the Preferred Reporting Items for Systematic reviews and Meta‐Analyses extension for Scoping Reviews (PRISMA‐Scr). A literature search was conducted on MEDLINE and EMBASE in Ovid on July 29th, 2021 for papers published from 1995 to July 2021. MeSH/EMTREE terms and keywords were used for the following concepts: Breast Cancer, Radiation Therapy, Cardiovascular, Treatment Outcomes. Search strategies were optimized for each database. After removing duplicates, 1341 papers were sent to title and abstract screening, of which 276 were sent to full‐text review. 160 studies were included for final data extraction. Agreement from two reviewers was required for an article to move to the next stage of screening. Eligibility criteria included primary clinical studies reporting a cardiovascular outcome of interest for patients who underwent BC RT.

Even with modern radiotherapy techniques, patients who have undergone BC RT face an increased risk of the development of cardiovascular morbidities. In the long term, the risk of cardiac disease increases with an increase in mean heart radiation dose. Early‐detection studies reveal that changes in cardiac dysfunction can be detected early on, often characterized by a decline in left ventricular ejection fraction. With most RT‐induced cardiac sequelae manifesting years after RT exposure, studies with a shorter follow‐up period often report lower CVD risk. Articles produced contrasting results regarding whether breast cancer radiation laterality increases the risk of CVD, with many indicating no difference while others concluded those with left‐sided radiation therapy have an increased risk. Detection and surveillance, with a combination of both cardiac biomarkers and imaging, is critical at an early stage for all women who have undergone BC RT.

With the majority of current surveillance techniques only detecting cardiovascular damage once it is too late, early detection is a critical prerequisite in improving cardiac sequelae prediction and prevention to ultimately improve breast cancer patients’ quality of life and care.

[1] Sung et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J Clin; 72(3):210‐249

[2] Correa et al. Coronary Artery Findings After Left‐Sided Compared with Right‐Sided Radiation Treatment for Early‐Stage Breast Cancer. J Clin Oncol, 2007; 25(21):3031‐3037