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 11, 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.