Department of Radiology, Tokyo Medical Center, Tokyo, Japan.
Int J Radiat Oncol Biol Phys. 2011 Nov 1;81(3):e127-33. doi: 10.1016/j.ijrobp.2011.01.012. Epub 2011 Mar 11.
To determine the rectal tolerance to Grade 2 rectal bleeding after I-125 seed brachytherapy combined with external beam radiotherapy (EBRT), based on the rectal dose-volume histogram.
A total of 458 consecutive patients with stages T1 to T3 prostate cancer received combined modality treatment consisting of I-125 seed implantation followed by EBRT to the prostate and seminal vesicles. The prescribed doses of brachytherapy and EBRT were 100 Gy and 45 Gy in 25 fractions, respectively. The rectal dosimetric factors were analyzed for rectal volumes receiving >100 Gy and >150 Gy (R100 and R150) during brachytherapy and for rectal volumes receiving >30 Gy to 40 Gy (V30-V40) during EBRT therapy in 373 patients for whom datasets were available. The patients were followed from 21 to 72 months (median, 45 months) after the I-125 seed implantation.
Forty-four patients (9.7%) developed Grade 2 rectal bleeding. On multivariate analysis, age (p = 0.014), R100 (p = 0.002), and V30 (p = 0.001) were identified as risk factors for Grade 2 rectal bleeding. The rectal bleeding rate increased as the R100 increased: 5.0% (2/40 patients) for 0 ml; 7.5% (20/267 patients) for >0 to 0.5 ml; 11.0% (11/100 patients) for >0.5 to 1 ml; 17.9% (5/28 patients) for >1 to 1.5 ml; and 27.3% (6/22 patients) for >1.5 ml (p = 0.014). Grade 2 rectal bleeding developed in 6.4% (12/188) of patients with a V30 ≤35% and in 14.1% (26/185) of patients with a V30 >35% (p = 0.02). When these dose-volume parameters were considered in combination, the Grade 2 rectal bleeding rate was 4.2% (5/120 patients) for a R100 ≤0.5 ml and a V30 ≤35%, whereas it was 22.4% (13/58 patients) for R100 of >0.5 ml and V30 of >35%.
The risk of rectal bleeding was found to be significantly volume-dependent in patients with prostate cancer who received combined modality treatment. Rectal dose-volume analysis is a practical method for predicting the risk of development of Grade 2 rectal bleeding.
根据直肠剂量-体积直方图，确定 I-125 种子近距离放疗联合外照射放疗（EBRT）后 2 级直肠出血的直肠耐受量。
共有 458 例 T1 至 T3 期前列腺癌患者接受了联合治疗，包括 I-125 种子植入后进行前列腺和精囊 EBRT。近距离放疗和 EBRT 的规定剂量分别为 100 Gy 和 45 Gy，共 25 次。对 373 例可提供数据集的患者，分析了接受 >100 Gy（R100）和 >150 Gy（R150）的直肠体积比（在近距离放疗期间），以及在 EBRT 治疗期间接受 >30 Gy 至 40 Gy（V30-V40）的直肠体积比。在 I-125 种子植入后，患者随访 21 至 72 个月（中位随访时间 45 个月）。
44 例（9.7%）患者发生 2 级直肠出血。多变量分析显示，年龄（p=0.014）、R100（p=0.002）和 V30（p=0.001）是 2 级直肠出血的危险因素。直肠出血发生率随 R100 的增加而增加：0 ml 为 5.0%（40 例中的 2 例）；>0 至 0.5 ml 为 7.5%（267 例中的 20 例）；>0.5 至 1 ml 为 11.0%（100 例中的 11 例）；>1 至 1.5 ml 为 17.9%（28 例中的 5 例）；>1.5 ml 为 27.3%（22 例中的 6 例）（p=0.014）。V30≤35%的患者中，2 级直肠出血发生率为 6.4%（188 例中的 12 例），V30>35%的患者中为 14.1%（185 例中的 26 例）（p=0.02）。当综合考虑这些剂量-体积参数时，R100≤0.5 ml 和 V30≤35%的患者 2 级直肠出血发生率为 4.2%（120 例中的 5 例），而 R100>0.5 ml 和 V30>35%的患者发生率为 22.4%（58 例中的 13 例）。
接受联合治疗的前列腺癌患者的直肠出血风险明显与体积有关。直肠剂量-体积分析是预测 2 级直肠出血发展风险的实用方法。
