Study On The Influence Of Peritumoral Brain Edema On The Delineation Of Radiotherapy Target Volume In High-grade Gliomas

PartⅠ Analysis of influencing factors in peritumoral brain edema of high-grade gliomasBackground:Peritumoral brain edema can occur in almost all tumors of central nervous system,the most common of which are high-grade gliomas and brain metastases.Tumor-associated edema can cause severe neurological defect symptoms and signs.With the occurrence and development of peritumoral brain edema,a great impact has been caused on patients’ quality of life,choices of treatment methods and efficacy evaluation.At present,it is still controversial that whether the patients’ personal clinical factors and tumor-related pathological factors could affect peritumoral brain edema of high-grade gliomas,which needs to be further explored and analyzed.Objective:The purpose of this study was to comprehensively analyze the influence of clinical and pathological factors on the peritumoral brain edema of gliomas,and to provide a reference for the choices of treatment methods and efficacy evaluation for patients with high-grade gliomas in our daily work.Methods:The clinical data of 85 patients with high-grade gliomas were retrospectively analyzed,and the peritumoral brain edema index was calculated systematically based on the imaging data and the target area delineation system.The edema index was used as a dependent variable to analyze the relevant factors affecting peritumoral brain edema.Results:(1)85 patients with high-grade gliomas were enrolled,including 27 cases(31.76%)with moderate peritumoral brain edema and 58 severe cases(68.24%);(2)There was no statistically significant difference in the peritumoral brain edema index of high-grade gliomas with age,gender,KPS score,and pathological grade;(3)The peritumoral brain edema index of high-grade gliomas was negatively correlated with tumor size,r=-0.897;(4)There was a statistically significant difference in peritumoral brain edema index of high-grade gliomas in different parts of the brain,P<0.05.Conclusion:In this study:(1)The size of high-grade gliomas is an important factor affecting the degree of peritumoral brain edema.Within a certain range,the extent of peritumoral brain edema is negatively correlated with tumor size;(2)The location of high-grade gliomas is a relevant factor affecting peritumoral brain edema,and the range of edema is different in different anatomical locations of the brain;(3)There is no difference in the severity of peritumoral brain edema in high-grade gliomas at the same anatomical location.Part Ⅱ The value of peritumoral brain edema in delineating clinical target volume of high-grade gliomasBackground:Glioma is the most common malignant tumor of the central nervous system.Radiotherapy has become the main adjuvant therapy for high-grade gliomas after operation.However,there is no clear consensus on whether the clinical target volume should include preoperative or postoperative peritumoral brain edema.Objective:The purpose of this study was to explore the reference value of preoperative and postoperative peritumoral brain edema for the delineation of clinical target volume of high-grade gliomas.Methods:The clinical data of 89 patients with high-grade gliomas were selected.Referring to the preoperative and postoperative imaging data to delineate the clinical target volume and formulate the radiotherapy plan respectively,namely,the simulated planning group and the treatment group.According to the general baseline characteristics,color wash,and dose-volume histogram(DVH)of the included patients,statistical analysis was performed on the target conformity index and the dose of organs at risk in the two groups to evaluate the clinical efficiency.Results:(1)There was a correlation between preoperative peritumoral brain edema and postoperative edema area in high-grade gliomas(r=0.899,P<0.05);(2)The conformity index of the treatment group was closer to 1.0 than that in the simulated planning group,and the difference between the two groups was statistically significant(Z=-3.093,P=0.001);(3)There was no statistical difference in the dose of organs at risk between the two groups(P>0.05).Compared with the simulated planning group,the potential of overdose was relatively lower in the treatment group,and the incidence of overdose for optic chiasma was significantly different between the two groups(x2=4.013,P=0.029).Conclusion:The findings of this study are as follows:(1)No matter referring to the preoperative or postoperative peritumoral brain edema for the delineation of the clinical target volume both can cover the target volume well,the later that referring to the postoperative imaging data has a better conformity;(2)Compared with that delineated by referring to preoperative peritumoral brain edema,the incidence of overdose of organs at risk is relatively lower in the plan based on postoperative imaging data.There is a statistical difference in the conformity index of the clinical target volume delineated by referring to postoperative peritumoral brain edema and preoperative peritumoral brain edema,which suggests that MRI examination after surgery and before radiotherapy is of great importance.During the delineation of the clinical target volume,preoperative and postoperative peritumoral brain edema should be both considered,and more emphasis should be placed on the reference of postoperative peritumoral brain edema.We think that postoperative peritumoral brain edema has great clinical guiding value for postoperative radiotherapy of high-grade gliomas.