Murakami Naoya, Kasamatsu Takahiro, Wakita Akihisa, Nakamura Satoshi, Okamoto Hiroyoki, Inaba Koji, Morota Madoka, Ito Yoshinori, Sumi Minako, Itami Jun
Department of Radiation Oncology, National Cancer Center Hospital, 5-1-1, Tsukiji Chuo-ku, Tokyo 104-0045, Japan.
BMC Cancer. 2014 Jun 17;14:447. doi: 10.1186/1471-2407-14-447.
In this study, high risk clinical target volumes (HR-CTVs) according to GEC-ESTRO guideline were contoured retrospectively based on CT images taken at the time of high-dose rate intracavitary brachytherapy (HDR-ICBT) and correlation between clinical outcome and dose of HR-CTV were analyzed.
Our study population consists of 51 patients with cervical cancer (Stages IB-IVA) treated with 50 Gy external beam radiotherapy (EBRT) using central shield combined with 2-5 times of 6 Gy HDR-ICBT with or without weekly cisplatin. Dose calculation was based on Manchester system and prescribed dose of 6 Gy were delivered for point A. CT images taken at the time of each HDR-ICBT were reviewed and HR-CTVs were contoured. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model (α/β = 10 Gy).
Three-year overall survival, Progression-free survival, and local control rate was 82.4%, 85.3% and 91.7%, respectively. Median cumulative dose of HR-CTV D90 was 65.0 Gy (52.7-101.7 Gy). Median length from tandem to the most lateral edge of HR-CTV at the first ICBT was 29.2 mm (range, 18.0-51.9 mm). On univariate analysis, both LCR and PFS was significantly favorable in those patients D90 for HR-CTV was 60 Gy or greater (p = 0.001 and 0.03, respectively). PFS was significantly favorable in those patients maximum length from tandem to edge of HR-CTV at first ICBT was shorter than 3.5 cm (p = 0.042).
Volume-dose showed a relationship to the clinical outcome in CT based brachytherapy for cervical carcinoma.
在本研究中，根据GEC-ESTRO指南，基于高剂量率腔内近距离放射治疗（HDR-ICBT）时所拍摄的CT图像，对高危临床靶区（HR-CTV）进行回顾性勾画，并分析临床结局与HR-CTV剂量之间的相关性。
我们的研究人群包括51例宫颈癌（IB-IVA期）患者，接受了50 Gy的外照射放疗（EBRT），采用中央屏蔽，并联合2-5次6 Gy的HDR-ICBT，同时使用或不使用每周顺铂。剂量计算基于曼彻斯特系统，规定给A点的剂量为6 Gy。回顾每次HDR-ICBT时拍摄的CT图像，并勾画HR-CTV。通过应用线性二次模型（α/β = 10 Gy）将剂量转换为2 Gy时的等效剂量（EQD2）。
三年总生存率、无进展生存率和局部控制率分别为82.4%、85.3%和91.7%。HR-CTV D90的中位累积剂量为65.0 Gy（52.7-101.7 Gy）。首次ICBT时从施源器到HR-CTV最外侧边缘的中位长度为29.2 mm（范围，18.0-51.9 mm）。单因素分析显示，HR-CTV的D90为60 Gy或更高的患者，其LCR和PFS均显著更佳（分别为p = 0.001和0.03）。首次ICBT时从施源器到HR-CTV边缘的最大长度短于3.5 cm的患者，其PFS显著更佳（p = 0.042）。
在基于CT的宫颈癌近距离放射治疗中，体积-剂量与临床结局相关。
