Radiation-induced Circulating microRNAs predict cardiac dysfunction after radiotherapy

Patients treated with radiotherapy to the chest region are at risk of cardiac sequelae, however, identification of those with greatest risk of complications remains difficult. Here, we sought to determine whether short-term changes in circulating miRNA expression are related to measures of cardiac dysfunction in follow-up. miRNA expression analysis in the primary group showed marked changes in serum miRNAs immediately after RT compared to baseline. miRNAs with increased expression correlated positively with cardiopulmonary dose-volume histogram metrics, while those with decreased expression exhibited negative correlations. Serum samples from 28 patients with left-sided breast cancer were collected before RT, 24h after the last dose and 1 month after RT; the patients were followed up for 3 years after completion of RT and cardiac echocardiography at 2.5-3 year follow-up was performed. All patients underwent adjuvant chemotherapy prior to RT, if indicated. Concomitant treatment with systemic therapies other than chemotherapy was allowed, including treatment with trastuzumab, tamoxifen or aromatase inhibitors.