Objective: To evaluate the incidence of early cardiac injury in patients with left-sided breast cancer receiving hypofractionated radiotherapy after breast conserving surgery, and to investigate the correlation between cardiac injury and hypofractionated radiotherapy dose. Methods: We prospectively enrolled 103 breast cancer patients who received whole breast with or without regional nodal irradiation after breast conserving surgery using either deep inspiration breath-hold (DIBH) or free breathing (FB) radiotherapy technique. Cardiac examinations that included N-terminal pro-B-type natriuretic peptide (NT-proBNP), electrocardiogram, and myocardial perfusion imaging were performed routinely before and after radiotherapy. The effects of heart dose, systemic therapy and individual factors (Framingham score) on the incidence of cardiac events were analyzed. Results: The median age was 48 years. The mean dose (Dmean) of the heart, left anterior descending coronary artery (LAD), left ventricular (LV), and right ventricular (RV) were 4.0, 16.9, 6.3, and 4.4 Gy, respectively. With a median follow-up of 13.4 months, no patient had clinical cardiac abnormalities. The incidence rates of subclinical cardiac events at 1- 6- and 12-month were 23.5%, 31.6%, and 41.3%, respectively. The DIBH group had a lower mean dose, maximum dose, and V5-V40 in the heart, LAD, LV, and RV than the FB group (P<0.001). Univariate analysis showed an increased incidence of subclinical cardiac events with heart Dmean >4 Gy, LAD V40 > 20%, LV Dmean >6 Gy, RV Dmean >7 Gy, or cumulative doses of anthracycline or taxane > 300 mg/m(2) (All P<0.05). Anti-HER2 targeted therapy, endocrine therapy and Framingham score were not associated with the incidence of subclinical cardiac events (all P>0.05). Multivariate analysis demonstrated that Dmean of LV and RV were independently associated with the increased incidence of subclinical cardiac events. Conclusions: Early subclinical heart injury are found in patients with left-sided breast cancer after hypofractionated radiotherapy. The increased incidence of subclinical cardiac events after radiotherapy is positively associated with the cardiac radiation doses.
目的： 观察左侧乳腺癌保乳术后放疗患者早期心脏损伤的发生情况，探讨大分割放疗与心脏损伤的剂量效应关系。 方法： 前瞻性入组103例左侧乳腺癌保乳术后行全乳±淋巴引流区放疗患者，根据患者呼吸控制能力，选择采用深吸气屏气(DIBH，54例)或自由呼吸(FB，49例)下放疗。分别在放疗前后定期进行心脏随访和相应心脏检查(B型脑钠肽前体、心电图、门控心肌灌注显像)，观察亚临床心脏事件的发生率。分析心脏剂量参数、心血管相关肿瘤药物治疗因素和个体因素(Framingham评分)对心脏事件发生率的影响。 结果： 全组患者的中位年龄为48岁，心脏平均剂量(Dmean)、冠脉左前降支(LAD)Dmean、左心室Dmean和右心室Dmean分别为4.0、16.9、6.3和4.4 Gy。中位随访13.4个月，全组患者未出现有临床症状的心脏事件。放疗后1、6和12个月的亚临床心脏事件发生率分别为23.5%、31.6%和41.3%。DIBH组与FB组比较，全心脏、LAD、左心室和右心室的Dmean、最大剂量(Dmax)和V5～V40均明显降低(均P<0.001)。单因素分析显示，心脏Dmean>4 Gy、LAD V40>20%、左心室Dmean>6 Gy、右心室Dmean>7 Gy和蒽环或紫杉类药物累积剂量>300 mg/m(2)的亚临床心脏事件发生率升高(均P<0.05)。多因素分析显示，左心室Dmean和右心室Dmean是亚临床心脏事件发生率的独立影响因素(均P<0.05)。 结论： 左侧乳腺癌保乳术后接受大分割放疗的患者可早期检测到亚临床心脏损伤，亚临床心脏事件的发生率与心脏剂量有关。.
Keywords: Breast neoplasms; Cardiac dose; Hypofractionated radiotherapy; Subclinical cardiac injury.