Ohashi Toshio, Yorozu Atsunori, Toya Kazuhito, Saito Shiro, Momma Tetsuo, Nagata Hirohiko, Kosugi Michio
Department of Radiology, Tokyo Medical Center, National Hospital Organization, Tokyo, Japan.
Jpn J Clin Oncol. 2007 Feb;37(2):121-6. doi: 10.1093/jjco/hyl133. Epub 2007 Jan 25.
To investigate rectal morbidity after I-125 prostate brachytherapy and to analyze predictive factors of rectal morbidity.
A group of 227 consecutive patients with localized prostate cancer were treated with I-125 prostate brachytherapy with or without external beam radiotherapy (EBRT) between September 2003 and January 2005. Rectal morbidity (diarrhea, bleeding and pain) was evaluated using the Radiation Therapy Oncology Group (RTOG) criteria. Dosimetry was based on computerized tomography (CT) scan 1 month post-implant. The clinical, treatment-related and dosimetric factors were evaluated for the risk of grade 2 rectal morbidity. Rectal dosimetric factors included the rectal volume that received >100% and 150% of the prescribed dose, and the maximal rectal dose which was defined as the sum of the minimal dose received by 1% of the rectum volume and the prescribed dose of EBRT.
Grade 2 rectal bleeding occurred in 10 (4.4%): for nine patients within the first year and for one patient between the first and second year. Grade 2 diarrhea occurred in one patient (0.4%) within the first year. No patient reported grade 2 pain. In the univariate analysis with grade 2 rectal bleeding, there were significant correlations with number of seeds, supplemental EBRT, and all of the rectal dosimetric parameters. On subsequent multivariate analysis, the only significant factor was the maximal rectal dose (P < 0.001). Rectal dose > 160 Gy was correlated to grade 2 rectal morbidity. All the patients with rectal dose > 160 Gy received EBRT.
Manifestations of rectal morbidity are acceptable events after I-125 prostate brachytherapy. Rectal dose-volume histogram for the brachytherapy is a predictive method for assessing the risk of developing grade 2 rectal bleeding. Delivery of the rectal dose should not exceed 160 Gy in order to avoid rectal complications.
研究¹²⁵I前列腺近距离放射治疗后直肠并发症，并分析直肠并发症的预测因素。
2003年9月至2005年1月，一组227例局限性前列腺癌患者接受¹²⁵I前列腺近距离放射治疗，部分联合外照射放疗（EBRT）。采用放射肿瘤学组（RTOG）标准评估直肠并发症（腹泻、出血和疼痛）。剂量测定基于植入后1个月的计算机断层扫描（CT）。评估临床、治疗相关和剂量学因素与2级直肠并发症风险的关系。直肠剂量学因素包括接受超过处方剂量100%和150%的直肠体积，以及最大直肠剂量，其定义为直肠体积的1%接受的最小剂量与EBRT处方剂量之和。
2级直肠出血发生10例（4.4%）：9例在第一年，1例在第一和第二年之间。2级腹泻在第一年发生1例（0.4%）。无患者报告2级疼痛。在2级直肠出血的单因素分析中，与粒子数量、补充EBRT以及所有直肠剂量学参数均有显著相关性。随后的多因素分析显示，唯一的显著因素是最大直肠剂量（P < 0.001）。直肠剂量>160 Gy与2级直肠并发症相关。所有直肠剂量>160 Gy的患者均接受了EBRT。
¹²⁵I前列腺近距离放射治疗后，直肠并发症表现为可接受事件。近距离放射治疗的直肠剂量体积直方图是评估2级直肠出血发生风险的预测方法。为避免直肠并发症，直肠剂量不应超过160 Gy。
