Gaudet Marc, Lim Peter, Yuen Conrad, Zhang Susan, Spadinger Ingrid, Dubash Rustom, Aquino-Parsons Christina
Department of Radiation Oncology, BC Cancer Agency Vancouver Centre, Vancouver, BC, Canada; Département de radio-oncologie, CSSS de Gatineau-Hôpital de Gatineau, Gatineau, QC, Canada.
Department of Radiation Oncology, BC Cancer Agency Vancouver Centre, Vancouver, BC, Canada.
Brachytherapy. 2014 May-Jun;13(3):257-62. doi: 10.1016/j.brachy.2014.01.001. Epub 2014 Jan 28.
The objective of this study was to determine if use of a rectal retractor (RR) in high-dose-rate intracavitary brachytherapy for cervical cancer reduces rectal dose parameters.
We reviewed data obtained from patients treated with intracavitary brachytherapy for cervical cancer with and without an RR. Treatment plans for each brachytherapy fraction were separated into two groups; R group with use of an RR and P group with use of vaginal packing. Dose-volume parameters for high-risk clinical target volume (HR-CTV), rectum, sigmoid, small bowel, and vaginal surface were collected for each fraction. Rectal D2cc and International Commission on Radiation Units & Measurements (ICRU) rectal point doses were compared between groups using Student's t tests. Predictors of higher rectal D2cc were determined by univariate and multivariate regression analyses.
Four hundred sixty-three brachytherapy fractions from 114 patients were used for analysis, 377 fractions with a RR (R group) and 86 with vaginal packing only (P group). Both groups were similar except for slightly higher mean HR-CTV and mean bladder volume in P group. Both mean ICRU rectal point dose (241.1 vs. 269.9 cGy, p = 0.006) and rectal D2cc (240.6 vs. 283.6 cGy, p < 0.001) were significantly higher in P group. Point A dose, HR-CTV, stage, and use of an RR were significant predictors of rectal D2cc on multivariate analysis.
Our data show that use of an RR leads to lower rectal dose parameters compared with vaginal packing. Further study is needed to determine if this will lead to less long-term toxicity.
本研究的目的是确定在宫颈癌高剂量率腔内近距离放射治疗中使用直肠牵开器（RR）是否能降低直肠剂量参数。
我们回顾了接受腔内近距离放射治疗的宫颈癌患者使用或未使用RR的数据。每次近距离放射治疗的治疗计划分为两组；使用RR的R组和使用阴道填塞物的P组。收集每个分次中高危临床靶区（HR-CTV）、直肠、乙状结肠、小肠和阴道表面的剂量体积参数。使用学生t检验比较两组之间的直肠D2cc和国际辐射单位与测量委员会（ICRU）直肠点剂量。通过单因素和多因素回归分析确定直肠D2cc较高的预测因素。
对114例患者的463个近距离放射治疗分次进行分析，377个分次使用RR（R组），86个分次仅使用阴道填塞物（P组）。除P组平均HR-CTV和平均膀胱体积略高外，两组相似。P组平均ICRU直肠点剂量（241.1 vs. 269.9 cGy，p = 0.006）和直肠D2cc（240.6 vs. 283.6 cGy，p < 0.001）均显著更高。多因素分析显示，A点剂量、HR-CTV、分期和RR的使用是直肠D2cc的显著预测因素。
我们的数据表明，与阴道填塞物相比，使用RR可降低直肠剂量参数。需要进一步研究以确定这是否会导致更少的长期毒性。
