The analysis of correlation between changes of myocardial enzymes level in serum before and after radiation and dose-volume histogram parameters of the heart

Abstract

Objective To analyze the correlation between the changes of myocardial enzyme level in serum before and after radiotherapy and dose - volume histogram ( DVH ) parameters of the heart.Methods A total of 102 patients with 68 cases of lung cancer and 34 cases of esophageal cancer were recruited.All patients received three-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT),with the radiation beams passing through the heart.Aspertate aminotransferase (AST),creatine kinase (CK),creatine kinase isozyme ( CK-MB ),lactate dehydrogenase ( LDH ),α-hydroxybutyrate dehydrogenase (α-HBDH) were determined in the serum before and after radiotherapy.All the enzyme levels before and after radiotherapy were compared through paired t-test.Independent sample t-test was conducted between sub-groups.And the dose-volume histogram (DVH) parameters of the heart were calculated ( the volume percentage of heart receiving dose equal to or exceeding x Gy ( Vx ).The correlation between myocardial enzyme level and DVH parameters was analyzed through Pearson method.Results Serum AST,CK-MB,LDH,α-HBDH levels increased significantly after radiotherapy ( 19.42∶ 27.89,14.72∶19.57,178.80 ∶ 217.57,140.32 ∶ 176.25,t =-3.39 - -6.92,all P=0.000).In Group IMRT,significant correlations between the increase of myocardial enzyme concentration and DVH parameters of the heart are found,AST with V20,V25,V30 of heart ( r=0.302 - 0.431,P =0.039 - 0.003 ),CK with V30of heart (r=0.345,P=0.013),and CK-MB,LDH,α-HBDH with V25,V30(r=0.465 -0.376,P=0.001-0.005).In Group CRT,there are significant correlations between changes of CK-MB,LDH level and V30 of heart (r =0.330,0.274,P=0.014,0.033),α-HBDH and V25,V30,and V35 of heart (r=0.270-0.331,P=0.046-0.014).When the irradiation dose was more than 50 Gy,significant correlations were found between the concentration changes of AST,LDH,α-HBDH and V25,V30 of heart (r=0.256-0.359,P =0.019-0.006),CK-MB and V30(r=0.233,P=0.037).When the irradiation dose was 50 Gy or less,only the concentration change of serum CK has significant correlation with V5 and V45 of heart (r=0.581,0.536,P=0.023,0.043).Conclusions There exists certain correlations between changes of myocardial enzymes level before and after radiation and DVH parameters of the heart,which indicates that the DVH parameters of heart are helpful to evaluate the radiation-induced myocardial damage. Key words: Thoracic neoplasma; Three-dimensional radiotherapy; Myocardial enzyme; Dose-volume histogram