Comparison Of Cardio-induced Heart Dieases After Hypofractionated Radiotherapy And Conventional Fractionated Radiotherapy In Early Left-side Breast Cancer Patients Who Receieved Breast Conserving Surgery

Background and Objective:Breast cancer is the most common malignancy among women in the world.The American Society for Therapeutic Radiology and Oncology(ASTRO)and National Comprehensive Cancer Network(NCCN)guidelines recomend hypofractionated radiotherapy(HF)as the optimal radiotherapy pattern after breast-conserving surgery for early breast cancer.The left breast is adjacent to the heart,and the total radiation dose to the heart in the left breast cancer patients is higher than the right breast cancer patients,which is more likely to cause higher incidence rate of radio-induced heart diseases(RIHD)and lower the patients' quality of life.By observing the changes of electrocardiogram(ECG),myocardial enzyme spectrum,cardiac troponin I(cTnI)and ultrasonic cardiogram(UCG)before and 3 months after radiotherapy in two groups,we comprehensively and systematically compared and evaluated the status of RIHD in left breast cancer patients,who treated with hypofractionated radiotherapy or conventional fractionated radiotherapy(CF).It provided the clinical basis for selecting the best radiotherapy mode for patients with early breast cancer after breast conserving surgery in China.Methods: From September 2017 to December 2019,60 patients with left early breast cancer after breast conserving surgery were randomly divided into two groups:the hypofractionated radiotherapy group and the conventional fractionated radiotherapy group,with 30 patients in each group.The prescription dose of the hypofractionated radiotherapy group was 42.5Gy/16 F in the left whole breast,while50 Gy / 25 F to the conventional fractionated radiotherapy group,after completing left whole breast radiotherapy dose,two groups were given 10Gy/5F radiation dose to tumor bed area with electron beam.Two groups of patients had ECG ? cardiac enzyme?cTnI and UCG before and three month after radiotherapy to compare the RIHD.The RIHD assessment in two groups according to Common TerminologyCriteria for Adverse Events Version 5.0(CTCAE5.0).Results:1.Comparison of basic conditions before radiotherapy: there was no significant difference between the two groups in age,myocardial enzyme parameters and UCG parameters before radiotherapy(P > 0.05).2.Comparison of cardiac dosimetry parameters before radiotherapy: there was no significant difference in cardiac V30,V40,minimum dose(Dmin)and mean dose(Dmean)between the two groups(P >0.05).The maximum cardiac dose(Dmax)of HF group was 183 cGy lower than that of CF group,and there was obvious difference in the cardiac Dmax between the two groups(P<0.05).3.Comparison of ECG abnormal rate after radiotherapy: In the HF group,there were 10 cases of abnormal ECG,all of which showed t-wave inversion,and the ECG abnormal rate was 33.33%.In the CF group,there were 11 cases of abnormal ECG,including 10 cases of T wave inversion and one case of sinus arrhythmia,with an abnormal ECG rate of 36.67%.There was no statistical difference in the abnormal ECG rate between the two groups(P > 0.05).4.Comparison of myocardial enzyme parameters after radiotherapy: the aspartate transaminase(AST),lactate dehydrogenase(LDH),creatine kinase(CK),and creatine kinase isoenzyme(CK-MB)of patients in the HF group were 27.30±6.79U/L,164.77±31.41U/L,91.03±41.58U/L and 14.73±4.67U/L,respectively.AST,LDH,CK and ck-mb in CF group were 29.37± 6.66U/L,170.20± 36.37U/L,98.63±30.75 U /L and 14.83± 3.93 u /L,respectively.There was no significant difference in myocardial enzyme parameters between the two groups after radiotherapy(P >0.05).5.Comparison of positive rate of cTnI after radiotherapy: the positive rate of cTnI was 0% in patients without positive cTnI in HF group.One patient with positive cTnI was found in CF group.The positive rate of cTnI was 3.33%.There was no significant difference in the positive rate of cTnI between the two groups after radiotherapy(P > 0.05).6.Comparison of UCG parameters after radiotherapy:The left ventricular ejection fraction(LVEF),left ventricular fractional shortening(LVFS),and the ratio ofmaximum peak velocity of left atriventricular valve in early diastole to that in late diastole(E/A)were 63.47±4.06%,34.37±3.00% and 1.12±0.48,respectively,in the HF group.The LVEF,LVFS and E/A values of CF group were 64.93±4.06%,35.00±3.87% and 1.11±0.41,respectively.There was no significant difference in cardiac ultrasound parameters between the two groups after radiotherapy(P > 0.05).7.Comparison of RIHD grading after radiotherapy: all the 14 RIHD patients in HF group were graded as grade 1(46.67%).Among the 11 patients with RIHD in the CF group,10 had grade 1 heart injury(33.33%)and 1 had grade 2 heart injury(3.33%).There was no significant difference in RIHD grading between the two groups(P >0.05).Conclusion: Compared with conventional fractionated radiotherapy,the time of radiotherapy is obviously shorter in hypofractionated radiotherapy,and which does not increase the risk of RIHD in patients with left breast conserving surgery.It has the advantage of money-saving and safety,and can be the preferred radiotherapy mode for the patients with left breast conserving surgery in china.