Analysis Of Safety And Dosimetry Of Immediate Breast Reconstruction Combined With Radiotherapy After Modified Radical Mastectomy

Objective: The main purpose is to investigate the effects of immediate breast reconstruction(IBR)combined with radiotherapy on safety and dosimetry of breast cancer patients after modified radical mastectomy.The secondary purpose of the study is to analyze the 5-year survival indexes and the effect of radiotherapy on breast appearance.Methods: The clinical records and follow-up data of 87 breast cancer patients diagnosed and treated in the Affiliated Tumor Hospital of Guangxi Medical University from January 2012 to December 2015 were analyzed retrospectively.According to whether the patients underwent IBR after modified radical mastectomy,they were divided into the immediate reconstruction group(41 cases)and non-reconstruction group(Simple modified radical mastectomy group,46 cases),all patients received postoperative radiotherapy.Comparing the postoperative radiotherapy-related complications,the conformity and homogeneity of the target dose distribution,and the amount of the organs at risk,analysis of the influencing factors of the complications,5-year local recurrence rate(LRR),and distant metastasis Rate(DMR),progression-free survival rate(PFS),overall survival rate(OS),and the effect of radiotherapy on the appearance of reconstructed breasts.Using IBM SPSS 25.0 software for statistical analysis,chi-square test,t test,univariate and bivariate logistic multivariate regression analysis,Kaplan-Meier method to describe survival curve,and Log-Rang test were used.Results: There was no significant difference in the incidence of related complications such as skin flap necrosis,infection,fat liquefaction necrosis,and secondary debridement after postoperative radiotherapy between the immediate reconstruction group and the non-reconstruction group(p>0.05).Univariate and multivariate analysis suggested that the range of body mass index(BMI)and diabetes mellitus were the influencing factors of related complications after postoperative radiotherapy(p<0.05).In the two groups of radiotherapy plans,the volume covered by the PCTV reaching 95% of the prescribed dose(PCTV-V95),the volume covered by the PCTV reaching 100% of the prescribed dose(PCTV-V100),and the volume covered by reaching 110% high volume area in the PCTV(PCTV-V110),the conformity index(CI)and homogeneity index(HI)of the target dose distribution were not statistically different(p>0.05).In the two groups of radiotherapy plans,the affected lung(V5,V20,V30,Dmean),the uninfected lung(V5,Dmean),the uninfected breast(V1,V5,Dmean),and the heart(V5,V20,V30,V40,Dmean)were not statistically different(p>0.05).There was no statistical difference in 5-year LRR,DMR,PFS,OS between the two groups(p>0.05).There was no statistical difference in the radiation skin reaction between the two groups(p>0.05).One case of prosthesis contracture was exposed after radiotherapy.The rest of the reconstructed breast did not appear deformed,and there was no tissue fibrosis that resulted in the stiffness of the breast.Conclusion: Radiotherapy immediately after breast reconstruction did not cause more obvious complications,and the safety of postoperative radiotherapy was acceptable.BMI≥25kg/m~2 and diabetes mellitus are the influencing factors of complications.IBR combined with radiotherapy compared with simple modified radical mastectomy radiotherapy,the conformability and homogeneity of the target dose distribution are similar,and the affected side lung(V5,V20,V30,Dmean),the contralateral lung(V5,Dmean),and the uninfected side Breast(V1,V5,Dmean),heart(V5,V20,V30,V40,Dmean)have equivalent limits for organs at risk.The survival benefit of IBR combined with radiotherapy and radiotherapy after simple modified radical mastectomy is similar.IBR combined with radiotherapy has no effect on the safety,dosimetry and survival of breast cancer patients,and has little effect on the appearance of reconstructed breasts,which can be clinically accepted.