Comparison of survival benefits between simultaneous integrated boost intensity-modulated radiotherapy and conventional fractionated radiotherapy for esophageal squamous cell carcinoma / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the survival benefits of simultaneous integrated boost intensity-modulated radiotherapy ( SIB-IMRT ) in the treatment of esophageal squamous cell carcinoma ( ESCC ) . Methods From July 2003 to March 2014,1748 patients with ESCC received 3DCRT or IMRT in a single institution were enrolled in this retrospective study. Among them, 809 patients received conventional fractionated radiotherapy with the standard prescription dose and 110 patients received SIB-IMRT ( SIB-IMRT group).Survival analysis was performed and propensity score matching (PSM 1vs1) was conducted to evaluate and compare the survival benefits between SIB-IMRT and conventional fractionated radiotherapy. Results The baseline characteristics significantly differed between two groups. In the SIB group,the age was significantly younger ( 64 years vs. 66 years, P=0. 001 ) , the percentage of patients with cervical/upper thoracic tumors was considerably higher (53. 6％ vs. 31. 0％,P=0. 000) and the proportion of N2 patients was significantly higher ( 21. 8％ vs. 13. 7％,P=0. 027) compared with those in the other group. Accordingto the PSM of 1:1, 218 patients were successfully matched. After matching, the clinical data did not significantly differ between two groups. Prior to matching,the median survival time in the standard dose and SIB-IMRT groups were 23 and 21 months (P=0. 638).After matching,the median survival time in the SIB-IMRT group was 22 months,significantly longer than 18 months in the standard dose group (P=0. 000). Subgroup analysis demonstrated that patients with large tumors ( GTV volume>40 cm3 ) and middle/lower thoracic tumors obtained more survival benefits from SIB-IMRT. The median survival time of patients in the standard dose group was 14 months, significantly shorter than 21 months in the SIB-IMRT group ( P=0. 001).The median survival time of patients with middle/lower thoracic tumors in the SIB-IMRT group was 17 months,significantly longer than 9 months in the standard dose group (P=0. 000).Multivariate analysis using Cox regression model indicated that age, tumor site and radiotherapy modality were the independent prognostic factors. The HR of SIB-IMRT was 0. 551(P=0. 000),which was a factor for survival benefits. Conclusions SIB-IMRT possesses potential survival benefits for ESCC compared with conventional fractionated radiotherapy. Patients with large tumors and middle/lower thoracic tumors are more prone to obtaining benefits from SIB-IMRT than their counterparts.