{"id":23506,"date":"2026-04-01T13:30:10","date_gmt":"2026-04-01T17:30:10","guid":{"rendered":"https:\/\/www.ices.on.ca\/?post_type=journal_article&#038;p=23506"},"modified":"2026-04-07T13:39:08","modified_gmt":"2026-04-07T17:39:08","slug":"long-term-risk-of-cardiovascular-disease-after-contemporary-left-sided-breast-radiation-therapy","status":"publish","type":"journal_article","link":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/long-term-risk-of-cardiovascular-disease-after-contemporary-left-sided-breast-radiation-therapy\/","title":{"rendered":"Long-term risk of cardiovascular disease after contemporary left-sided breast radiation therapy"},"content":{"rendered":"<p><strong>Importance<\/strong> \u2014 External beam radiation therapy (EBRT) for left-sided breast cancer historically increased the risk of cardiovascular disease (CVD). Advances in EBRT have reduced mean heart dose, but contemporary population-level data on long-term cardiovascular outcomes remain limited.<\/p>\n<p><strong>Objective<\/strong> \u2014 To examine whether contemporary left-sided EBRT is associated with different long-term CVD risk than right-sided EBRT among women with breast cancer.<\/p>\n<p><strong>Design, setting, and participants<\/strong> \u2014 This population-based, retrospective cohort study used linked administrative health databases in Ontario, Canada, to identify women who received EBRT after a diagnosis of unilateral breast cancer between April 1, 2002, and December 31, 2017. Patients were followed up through February 28, 2025, for most outcomes and December 31, 2022, for cause-specific mortality. Data analysis was completed in August 2023 (with revisions in August 2025).<\/p>\n<p><strong>Exposure<\/strong> \u2014 Tumor laterality (left vs right).<\/p>\n<p><strong>Main outcomes and measures<\/strong> \u2014 The primary outcome was hospitalization with a most responsible diagnosis of CVD. Secondary outcomes included all-cause mortality, cardiovascular mortality, hospitalizations for specific CVD diagnoses, coronary revascularization, and new diagnoses of ischemic heart disease, heart failure, and atrial fibrillation. Cumulative incidence functions estimated the 15-year risk of outcomes accounting for the competing risk of death; event rates per 100 person-years captured recurrent events.<\/p>\n<p><strong>Results<\/strong> \u2014 Among 76\u202f586 women (mean [SD] age, 59 [12] years; 38\u202f427 [50.2%] with left-sided tumors) followed up for a median (IQR) of 10.9 (7.7-15.2) years, the 15-year cumulative incidence of first CVD hospitalization did not differ by laterality (left: 13.8% [95% CI, 13.4%-14.2%]; right: 13.5% [95% CI, 13.1%-13.9%]; P\u2009=\u2009.43). In women with preexisting CVD, new diagnoses of heart failure (10.2% [95% CI, 9.9%-10.6%] vs 9.6% [95% CI, 9.2%-10.0%]; P\u2009=\u2009.01) and ischemic heart disease (13.6% [95% CI, 13.2%-14.0%] vs 12.8% [95% CI, 12.4%-13.2%]; P\u2009=\u2009.03) were slightly more frequent after left-sided EBRT. The rate of CVD hospitalizations when including recurrent events was modestly higher for left-sided disease (1.72 vs 1.63 per 100 person-years; P\u2009=\u2009.006). Among women with preexisting CVD, there were no differences in all-cause mortality or recurrent CVD hospitalizations.<\/p>\n<p><strong>Conclusions and relevance<\/strong> \u2014 In this cohort study of women treated with EBRT for breast cancer in the past 2 decades, left-sided breast cancer radiation therapy was associated with minimal increases in long-term cardiovascular risk. These findings suggest that contemporary photon-based EBRT techniques have substantially reduced the cardiovascular risk historically associated with left-sided breast cancer radiation therapy.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Importance \u2014 External beam radiation therapy (EBRT) for left-sided breast cancer historically increased the risk of cardiovascular disease (CVD). Advances in EBRT have reduced mean heart dose, but contemporary population-level data on long-term cardiovascular outcomes remain limited. Objective \u2014 To examine whether contemporary left-sided EBRT is associated with different long-term CVD risk than right-sided EBRT [&hellip;]<\/p>\n","protected":false},"template":"","migration-helper-automated":[],"migration-manual":[],"topic":[38,40],"migration-helper-qa-sample-set":[],"class_list":["post-23506","journal_article","type-journal_article","status-publish","hentry","topic-cancer-and-cancer-screening","topic-cardiovascular-disease"],"acf":{"citation":"Nakajima E, Nguyen L, Liu N, Rodin D, Amir E, Austin PC, Thavendiranathan P, Abdel-Qadir H. <em>JAMA Netw Open<\/em>. 2026; 9(4): e264098.","source_url":"https:\/\/doi.org\/10.1001\/jamanetworkopen.2026.4098","ices_scientist":[1385,1379],"site":[6733],"research_program":[6742],"news_release":"","journal_article":"","atlas":"","research_report":"","infographic":"","video":"","downloads":null,"links":null,"sitecore_item_id":"","sitecore_item_name":"","sitecore_field_values":"","previous_url":""},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>ICES | Long-term risk of cardiovascular disease after contemporary left-sided breast radiation therapy<\/title>\n<meta name=\"description\" content=\"Importance \u2014 External beam radiation therapy (EBRT) for left-sided breast cancer historically increased the risk of cardiovascular disease (CVD). 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