Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA.
Int J Radiat Oncol Biol Phys. 2010 May 1;77(1):139-46. doi: 10.1016/j.ijrobp.2009.04.052. Epub 2009 Oct 14.
To assess the correlation of postimplant dosimetric quantifiers with biochemical control of prostate cancer after low-dose rate brachytherapy.
The biologically effective dose (BED), dose in Gray (Gy) to 90% of prostate (D(90)), and percent volume of the prostate receiving 100% of the prescription dose (V(100)) were calculated from the postimplant dose-volume histogram for 140 patients undergoing low-dose rate prostate brachytherapy from 1997 to 2003 at Durham Regional Hospital and the Durham VA Medical Center (Durham, NC).
The median follow-up was 50 months. There was a 7% biochemical failure rate (10 of 140), and 91% of patients (127 of 140) were alive at last clinical follow-up. The median BED was 148 Gy (range, 46-218 Gy). The median D(90) was 139 Gy (range, 45-203 Gy). The median V(100) was 85% (range, 44-100%). The overall 5-year biochemical relapse-free survival (bRFS) rate was 90.1%. On univariate Cox proportional hazards modeling, no pretreatment characteristic (Gleason score sum, age, baseline prostate-specific antigen, or clinical stage) was predictive of bRFS. The BED, D(90), and V(100) were all highly correlated (Pearson coefficients >92%), and all were strongly correlated with bRFS. Using the Youden method, we identified the following cut points for predicting freedom from biochemical failure: D(90) >or= 110 Gy, V(100) >or= 74%, and BED >or= 115 Gy. None of the covariates significantly predicted overall survival.
We observed significant correlation between BED, D(90), and V(100) with bRFS. The BED is at least as predictive of bRFS as D(90) or V(100). Dosimetric quantifiers that account for heterogeneity in tumor location and dose distribution, tumor repopulation, and survival probability of tumor clonogens should be investigated.
评估低剂量率近距离放射治疗后前列腺癌生化控制与植入后剂量学定量指标的相关性。
对 1997 年至 2003 年期间在达勒姆地区医院和达勒姆退伍军人医疗中心（北卡罗来纳州达勒姆）接受低剂量率前列腺近距离放射治疗的 140 名患者的植入后剂量-体积直方图进行计算，得到生物有效剂量（BED）、前列腺 90%（D（90））的格雷剂量（Gy）和接受处方剂量 100%的前列腺体积百分比（V（100））。
中位随访时间为 50 个月。生化失败率为 7%（140 例中有 10 例），最后一次临床随访时 91%（140 例中有 127 例）的患者存活。中位 BED 为 148Gy（范围为 46-218Gy）。中位 D（90）为 139Gy（范围为 45-203Gy）。中位 V（100）为 85%（范围为 44-100%）。总的 5 年生化无复发生存率（bRFS）为 90.1%。在单因素 Cox 比例风险模型中，无预处理特征（Gleason 评分总和、年龄、基线前列腺特异性抗原或临床分期）可预测 bRFS。BED、D（90）和 V（100）均高度相关（Pearson 系数>92%），且均与 bRFS 密切相关。使用 Youden 方法，我们确定了以下预测生化失败无复发的切点：D（90）>or=110Gy，V（100）>or=74%，BED>or=115Gy。没有协变量显著预测总生存率。
我们观察到 BED、D（90）和 V（100）与 bRFS 之间存在显著相关性。BED 对 bRFS 的预测至少与 D（90）或 V（100）一样准确。应研究能够解释肿瘤位置和剂量分布异质性、肿瘤再增殖以及肿瘤克隆原生存概率的剂量学定量指标。
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