Robert Lee W, Deguzman Allan F, McMullen Kevin P, McCullough David L
Radiation Oncology, Winston-Salem, NC 27157, USA.
Int J Radiat Oncol Biol Phys. 2005 Jan 1;61(1):52-9. doi: 10.1016/j.ijrobp.2004.05.006.
To describe the relationship between two commonly used dosimetric quantifiers (dose received by 90% of the prostate [D(90)] and volume receiving 100% of dose [V(100)]) and biochemical disease-free survival (bDFS) in a cohort of men treated with low-dose-rate prostate brachytherapy (LDRPB).
The information in this report concerned the first 63 men treated with LDRPB alone at our institution between September 1997 and September 1998. All men had histologically confirmed, clinically localized prostate cancer. All men were treated with(125)I. The prescription dose was 144 Gy according to the Task Group 43 formalism. LDRPB was performed jointly by a radiation oncologist and urologist. Dosimetric quantifiers (D(90), V(100)) were calculated from a CT scan performed 1 month after LDRPB. Biochemical recurrence was defined according to the American Society for Therapeutic Radiology and Oncology consensus definition. Biochemical relapse-free survival (bRFS) was estimated using the product-limit method. D(90) and V(100) were examined as putative covariates for bRFS using the proportional hazards regression method. All p values are two-sided.
The median follow-up for the entire cohort was 62 months. The median D(90) was 122 Gy (range, 57-171Gy), and in 16 (25%) of 63 patients, the calculated D(90) was >140 Gy. The median V(100) was 81% (range, 51-97%). Nine men developed evidence of biochemical relapse at a median of 19 months (range, 6-38 months). The 5-year estimate of bRFS was 85% (95% confidence interval, 80-90%). The 5-year estimates of bRFS according to D(90) were as follows: D(90) > or =140 Gy, 86%; D(90) <140 Gy, 84% (p = not statistically significant). No threshold value of D(90) was predictive of the 5-year estimates of bRFS until the D(90) was <80 Gy (D(90) > or =80 Gy, 89%; D(90) <80 Gy, 50%; p = 0.02). The 5-year estimates of bRFS according to V(100) were as follows: V(100) > or =85%, 87%; V(100) <85%, 84% (p = not statistically significant). No threshold value of V(100) was predictive of the 5-year estimates of BRFS unless the dosimetry was particularly poor. The 5-year BRFS was 89% if the V(100) was > or =65% compared with 40% if the V(100) was <65% (p = 0.006).
The dosimetric or quantifiers described in this report did not predict for bRFS after LDRPB unless the dosimetry was very poor. This finding is not in complete agreement with those of previous reports. Possible reasons for this observation are (1) the study in underpowered, (2) inherent measurement error, (3) dosimetric quantifiers are poor surrogates of the dose received by the cancer, and (4) length of follow-up. Additional work in the area of quality assessment after LDRPB is required.
描述在接受低剂量率前列腺近距离放射治疗（LDRPB）的男性队列中，两个常用的剂量学定量指标（90%前列腺接受的剂量[D(90)]和接受100%剂量的体积[V(100)]）与生化无病生存率（bDFS）之间的关系。
本报告中的信息涉及1997年9月至1998年9月期间在我们机构仅接受LDRPB治疗的前63名男性。所有男性均经组织学证实为临床局限性前列腺癌。所有男性均接受(125)I治疗。根据任务组43形式主义，处方剂量为144 Gy。LDRPB由放射肿瘤学家和泌尿科医生联合进行。剂量学定量指标（D(90)、V(100)）根据LDRPB后1个月进行的CT扫描计算得出。生化复发根据美国放射治疗与肿瘤学会的共识定义确定。使用乘积限法估计生化无复发生存率（bRFS）。使用比例风险回归方法将D(90)和V(100)作为bRFS的假定协变量进行检验。所有p值均为双侧。
整个队列的中位随访时间为62个月。中位D(90)为122 Gy（范围57 - 171 Gy），63例患者中有16例（25%）计算得出的D(90) > 140 Gy。中位V(100)为81%（范围51 - 97%）。9名男性出现生化复发证据，中位时间为19个月（范围6 - 38个月）。bRFS的5年估计值为85%（95%置信区间，80 - 90%）。根据D(90)得出的bRFS的5年估计值如下：D(90)≥140 Gy，86%；D(90) <
