To Investigate The Efficacy And Toxicities In Replanning For Local Advanced Cervical Carcinoma Receiving Imrt

Objective:to explore the effects to the dose of organs at risk,short-term therapeutic efficacy and toxicities in locally advanced cervical cancer receiving the changed plan of intensity-modulated radiotherapy.Methods:7patients with LACC, receiving pretreatment pelvic magnetic resonance and weekly magnetic resonance scans, assessed the change of tumor volume to get a curve of time-volume and found the most significant time of changes of tumor volume. Between Mar,2010and Oct,2011,51patients with histologically confirmed LACC, receiving radical radiotherapy (RT), were recruited to this study in the Cancer Hospital. These patients were randomly divided into two groups:25patients accepting adaptable replaning for IMRT was group A.26patients receiving IMRT was group B. All the patients received brachytherapy in combination with chemotherapy. Group A received the second pelvic magnetic resonance and CT simulation to replan the planning in the most significant time of changes of tumor volume, Group A did not adjust the plan defined for Plan1(P1), after the repositioning plan were defined as Plan2(P2). The IMRT program of group B had no change. Concurrent weekly administration of chemotherapy was cisplatin30mg/m2for six cycles with RT. The changes of tumor volume, dose and volume parameter of organ at risk (OAR) were compared in Group A. The short-term therapeutic efficacy and acute side effects were compared between Group A and Group B.Results:The tumor volume of LACC receiving radical radiotherapy was reduced weekly. The third week was the most significant time of changes of tumor volume. In25patients of group A, the pre-treatment volume was81.7cm3(34.8～136.7cm3). After receiving the RT of33Gy, the volume was39.75cm3(14.87-65.86cm3), the incidence of patients’volume reducing by less than40%, between40%and60%, more than60%were9,10and6. In Group A the changes of dose-volume in rectum was statistically significant (P=0.012) with39.18%±9.39%of V40in plan P1and34.54%±6.47%in plan P2, and the statistically significant (P=0.003) changes also found in rectum with31.95%±10.52%of V50in plan P1and26.47%±9.98%in plan P2; the changes of dose-volume in urinary bladder was statistically significant (P=0.013) with39.47%±5.23%of V40in plan P1and34.87%±6.53%in plan P2, and the statistically significant (P=0.007) changes also found in bladder with36.28%±7.67%of V50in plan PI and30.62%±6.53%in plan P2. Between Group A and B,3months after RT, assessing the short-term therapeutic efficacy and comparing the incidence of acute effect in rectum and urinary bladder:the difference of the efficacy was not statistically significant (P>0.05) with96.0%in Group A and92.3%in Group B; Although the incidence of Grade II rectum and urinary bladder acute effect in Group Awere lower than Group B (16.0%vs26.9%and20%vs30.8%), the differences were not statistically significant (P>0.05).Conclusions:The patients of LACC, receiving IMRT followed brachytherapy, were necessary to have CT simulation again and modify the RT plan at a right time, in order to bring the dose in ORA down, reducing the incidence of side effects, at the same time, the program changed did not bring the short-term therapeutic efficacy down.