The Clinical Comparison Of Combined Intracavitary-interstitial Brachytherapy And Intracavitary Brachytherapy In Locally Advanced Squamous Cell Cervical Cancer

Objective:The purpose of this study is to compare the difference of dosimetric,adverse reactions,and prognosis between interstitial-intracavitary brachytherapy and intracavitary brachytherapy（ICBT）of locally advanced cervical cancer（LACC）to explore the safety and feasibility of this treatment model.Methods:A retrospective review of 74 patients with LACC diagnosed and treated in the Department of Radiotherapy,the First Hospital of Jilin University,was conducted from January 2013 to December 2017.The patients received external beam radiation therapy and computerized tomography-guided brachytherapy with dose prescription.The patients were divided into 2 groups according to the brachytherapy technique:uterine tandem/ovoids with the intracavitary（IC）technique and uterine tandem/metal needles with intracavitary-interstitial（IC-IS）technique.The dosimetric outcome,adverse reactions,disease-free survival（DFS）,and local control rate（LC）were evaluated between 2 groups.Differences between IC-IS brachytherapy and ICBT were tested with multivariable analysis.Results:A total of 74 patients with LACC were included in this study.The mean age in the patients with radiation therapy was 57 years old（32-84 years old）,including 57 patients（77%）who were less than 65 years old;the age in 17 cases of them was more than 65years old（23%）.The median HR-CTV_D90（EQD2）dose was 93.1（87.0-98.7）Gy in the IC-IS group and 95.9（87.8-99.2）Gy in the IC group.The median D2cc（Gy,EQD2）of bladder,rectum,sigmoid,and bowel were 86.0（76.7-103.2）Gy,73.3（65.9-80.7）Gy,59.7（56.5-61.0）Gy and 67.1（57.4-75.5）Gy,respectively,in the IC-IS group,and 85.9（78.1-101.2）Gy,73.8（65.5-82.1）Gy,61.9（58.3-68.7）Gy and 67.7（60.2-79.7）Gy,respectively,in IC group.DFS in the patients 3 years after treatment all was 73%in both groups,and LC was 86.5%（n=31）and 83.8%（n=30）,for IC-IS and IC groups.There were 13 and 10 cases in the patients with radiation toxicities,respectively,in IC-IS and IC groups,and the patients with G4 toxicities were not observed in both groups.Actuarial 3-year DFS in IC-IS and IC groups were 75.5%and 67.6%,and 3-year LC were 91.6%and 77.1%.The short-term response rate（CR+PR）in the IC group and IC-IS group were 94%and 100%,and the proportion of CR cases were 51.4%and 75.5%,respectively.Conclusion:In this study,univariate analysis showed that advanced stage,lymph node invasion,long overall treatment time,and parametrial extension are the main factors for lower 3-year DFS and LC.Besides,vaginal extension and the intracavitary technique resulted in lower local control rate.Intracavitary-interstitial technique allows for more stable brachytherapy doses,higher proportion of CR rate,better local control rate without increased radiation toxicities.All statistic indicated that intracavitary-interstitial technique can be a preferable choice for LACC patients.