Xu Dandan, Li Guowen, Li Hongfei, Jia Fei
Department of Radiation Oncology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
Medicine (Baltimore). 2017 Aug;96(31):e7685. doi: 10.1097/MD.0000000000007685.
Esophageal cancer (EC) is a common cancer with high mortality because of its rapid progression and poor prognosis. Radiotherapy is one of the most effective treatments for EC. Three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) are 2 recently developed radiotherapy techniques. IMRT is believed to be more effective than 3D-CRT in target coverage, dose homogeneity, and reducing toxicity to normal organs. However, these advantages have not been demonstrated in the treatment of EC. This meta-analysis was performed to compare IMRT and 3D-CRT in the treatment of EC in terms of dose-volume histograms and outcomes including survival and toxicity.
A literature search was performed in PubMed, Embase, and the Cochrane library databases from their inceptions to Dec 30, 2016. Two authors independently assessed the included studies and extracted data. The average percent irradiated volumes of adjacent noncancerous organs were calculated and compared between IMRT and 3D-CRT. The odds ratio of overall survival (OS), and radiation pneumonitis and radiation esophagitis was also evaluated.
Totally 7 studies were included. Of them, 5 studies (80 patients) were included in the dosimetric comparison, 3 studies (871 patients) were included in the OS analysis, and 2 studies (205 patients) were included in the irradiation toxicity analysis. For lung in patients receiving doses ≥20 Gy and heart in patients receiving dose = 50 Gy, the average irradiated volumes of IMRT were less than those from 3D-CRT. IMRT resulted in a higher OS than 3D-CRT. However, no significant difference was observed in the incidence of radiation pneumonitis and radiation esophagitis between 2 radiotherapy techniques.
Our data suggest that IMRT-delivered high radiation dose produces significantly less average percent volumes of irradiated lung and heart than 3D-CRT. IMRT is superior to 3D-CRT in the OS of EC while shows no benefit on radiation toxicity.
食管癌（EC）是一种常见癌症，因其进展迅速且预后较差，死亡率较高。放射治疗是食管癌最有效的治疗方法之一。三维适形放疗（3D-CRT）和调强放疗（IMRT）是最近开发的两种放疗技术。人们认为IMRT在靶区覆盖、剂量均匀性以及降低对正常器官的毒性方面比3D-CRT更有效。然而，这些优势在食管癌治疗中尚未得到证实。本荟萃分析旨在根据剂量体积直方图以及包括生存和毒性在内的结果，比较IMRT和3D-CRT在食管癌治疗中的效果。
在PubMed、Embase和Cochrane图书馆数据库中进行文献检索，检索时间范围从各数据库建库至2016年12月30日。两位作者独立评估纳入研究并提取数据。计算并比较IMRT和3D-CRT之间相邻非癌器官的平均受照体积百分比。还评估了总生存期（OS）、放射性肺炎和放射性食管炎的比值比。
共纳入7项研究。其中，5项研究（80例患者）纳入剂量学比较，3项研究（871例患者）纳入OS分析，2项研究（205例患者）纳入照射毒性分析。对于接受≥20 Gy剂量的患者的肺部以及接受50 Gy剂量的患者的心脏，IMRT的平均受照体积小于3D-CRT。IMRT的OS高于3D-CRT。然而，两种放疗技术在放射性肺炎和放射性食管炎的发生率方面未观察到显著差异。
我们的数据表明，与3D-CRT相比，IMRT给予的高辐射剂量使肺部和心脏的平均受照体积百分比显著降低。IMRT在食管癌的OS方面优于3D-CRT，但在辐射毒性方面未显示出优势。
