Correlation Analysis Between Supraclavicular Radiotherapy And Radiation-induced Brachial Plexopathy After Breast Cancer Surgery

Objective:To analyze the radiation dose and volume of brachial plexus in patients with supraclavicular radiotherapy after breast cancer surgery,to clarify the correlation between supraclavicular radiotherapy and radiation-induced brachial plexopathy(RIBP),and to strengthen clinicians’understanding of radiation-induced brachial plexopathy to prevent it occur.Methods:A total of 58 postoperative patients with breast cancer who met the inclusion and exclusion criteria and received supraclavicular radiotherapy in our hospital from 2018to 2020 were analyzed retrospectively.Clinical symptoms,auxiliary examinations and other data were collected to determine whether radiation-induced brachial plexopathy occurred.According to the brachial plexus delineation guidelines proposed by RTOG,the brachial plexus was delineated in the Pinnacle system,and the radiation dose and volume parameters were obtained by DVH.Analyzing the correlation between total brachial plexus volume,Dmax,Dmean,V10,V20,V30,V40,V50 and radiation-induced brachial plexopathy.Measurement data were expressed as mean±standard deviation(x±s)or frequency.Continuous variables were compared by independent samples T test,categorical variables were compared by Chi-square test or Fisher’s exact test,and dose and volume parameters were analyzed by binary logistic regression.The parameters with statistical differences were analyzed by ROC curve,and the optimal cutoff value was obtained.According to the optimal cutoff value,it was divided into small volume group and large volume group,and the difference between the two groups was compared by chi-square test or Fisher precision test,and P<0.05 was statistically significant.Results:There were 26 patients diagnosed with RIBP(RIBP group)and 32 non-RIBP patients(non-RIBP group).Univariate analysis was performed on parameters such as total brachial plexus volume V,Dmax,Dmean,V10,V20,V30,V40 and V50.The results showed that the total volume of brachial plexus in the RIBP group was(9.53±1.79)cm~3,while that in the non-RIBP group was(8.03±0.84)cm~3,and the difference was statistically significant(P=0.001);the V40 in the RIBP group was(5.65±2.20)cm~3,the non-RIBP group was(4.31±1.18)cm~3,the difference was statistically significant(P=0.001).While brachial plexus Dmax,Dmean,V10,V20,V30,V50,and relative volume of V10,V20,V30,V40 and V50 were no significant difference(all P>0.05).Multivariate analysis was performed on the total brachial plexus volume V,Dmax,Dmean and V40.The results showed that:the larger the total volume of brachial plexus,the higher the risk of RIBP,with statistical significance(OR=2.50,95%CI 2.11-7.42,P=0.024);the increase of brachial plexus Dmean will increase the risk of RIBP,with difference was statistically significant(OR=2.64,95%CI0.41-0.99,P=0.046);the larger the V40,the higher the risk of RIBP,which was statistically significant(OR=8.30,95%CI 1.46-48.53,P=0.045);There was no significant difference in Dmax of plexus nerves(P>0.05);the total volume of brachial plexus,Dmean and V40 of brachial plexus were analyzed by ROC curve,and the results were as follows:AUC of total volume of brachial plexus was 0.972,and cutoff value was 7.735cm~3(P<0.001);AUC of V40 was 0.708,and cutoff value was6.455cm~3(P=0.008);AUC of Dmean was 0.343cm~3,and cutoff value was 0.04(P=0.041).The AUC of total brachial plexus volume and V40 were bigger than 0.700,and Dmean AUC less than 0.500.According to cutoff value of total brachial plexus volume,there were 32 cases in small volume group 1(V<7.735cm3),26 cases in large volume group 1(V≥7.735cm3),and 6 cases(23.08%)of RIBP in small volume group 1,20 cases(76.92%)of RIBP in large volume group 1,the difference was statistically significant(P<0.001).According to CUTOFF value of V40,we divided into small volume group 2(V40<6.455cm3)36 cases,large volume group 2(V≥6.455cm3)22 cases,RIBP in small volume group 2 were 9 cases(25.00%),and RIBP in large volume group 2 were 17 cases(77.27%),the difference was statistically significant(P<0.001).Conclusions:The occurrence of radiation-induced brachial plexopathy was correlated with the total brachial plexus volume V,Dmean,and V40.The higher the total brachial plexus volume V,Dmean,and V40 was,the greater the risk of RIBP.The total brachial plexus volume and V40 have a good predictability for radiation-induced brachial plexopathy,and total brachial plexus volume was better than V40 in predicting the occurrence of RIBP.