Katcher J, Kupelian P A, Zippe C, Klein E A, Sohn J W
Department of Radiation Oncology, The Cleveland Clinic Foundation, OH 44195, USA.
Int J Radiat Oncol Biol Phys. 1997 Mar 1;37(4):871-6. doi: 10.1016/s0360-3016(96)00617-7.
The indications for treating the seminal vesicles (SV) in patients with clinically localized carcinoma of the prostate are controversial. We sought to define subgroups of patients in whom coverage could be avoided, using pretreatment prostate specific antigen (PSA) values and the Gleason score. Because the rectum is the major dose-limiting structure, we also measured the extent of rectal sparing achieved by excluding the SV from external beam treatment fields.
We retrospectively studied lateral x-ray simulation films of 43 patients treated with standard four-field radiotherapy and dose-volume histograms of eight patients treated with conformal radiotherapy. The rectal surface areas were measured and the volumes were calculated including and excluding the SV. The pathology reports of patients treated with radical prostatectomy alone between 1987 and 1993 were reviewed. Patients without preoperative PSA levels or biopsy Gleason scores, or who received neoadjuvant hormonal therapy were excluded. Of the 368 remaining patients, 66 (18%) had preoperative PSA levels < or = 4, 172 (47%) had PSA levels 4-10, and 130 (35%) had PSA levels > 10. The Gleason score was < or = 6 in 269 (73%), and 99 (27%) had a score > or = 7.
The reduction in the total irradiated rectal areas to full doses when the SV were excluded ranged from 5 to 67% in individual patients (median, 44%). The median reduction in the irradiated rectal volumes to 50% of the prescribed dose, as determined by dose-volume histograms, was 51% (range: 37-76%). The median reduction in bladder volumes was 9% (range: 6%-15%). The incidence of SV involvement was 19% (70 out of 368). Patients with normal PSA levels (< or = 4 ng/mL) had a 3% (2 out of 66) rate of SV involvement. Patients with PSA levels between 4-10 ng/mL had a 8% (10 out of 126) rate of SV involvement. All other cases had at least 20% rate of SV involvement, with a combined rate of 33%. Using a cutoff of 15%, two low risk groups were identified: all patients with PSA levels < or = 4, and patients with PSA 4-10 and Gleason score < or = 6. These constituted 52% (192 out of 368) of all patients. Overall, the low-risk patients had a 6% (12 out of 192) incidence of SV involvement vs. 33% (58 out of 176) for the high risk patients (p < or = .001).
Excluding the SV from the treatment field can significantly reduce (40%-50%) the volume of irradiated rectum. Our data confirm that pretreatment PSA levels and Gleason scores can be effectively used to define subgroups of patients in whom SV irradiation can be avoided. We propose excluding the SV in all patients with PSA levels < or = 4, and patients with PSA levels 4-10 and a Gleason score < or = 6.
对于临床局限性前列腺癌患者，精囊（SV）的治疗指征存在争议。我们试图利用治疗前前列腺特异性抗原（PSA）值和 Gleason 评分来确定可以避免照射精囊的患者亚组。由于直肠是主要的剂量限制结构，我们还测量了通过将精囊排除在体外照射野之外所实现的直肠受照剂量减少程度。
我们回顾性研究了 43 例接受标准四野放疗患者的侧位 X 线模拟片以及 8 例接受适形放疗患者的剂量体积直方图。测量直肠表面积并计算包括和不包括精囊时的体积。回顾了 1987 年至 1993 年间仅接受根治性前列腺切除术患者的病理报告。排除术前 PSA 水平或活检 Gleason 评分缺失或接受新辅助激素治疗的患者。在其余 368 例患者中，66 例（18%）术前 PSA 水平≤4，172 例（47%）PSA 水平为 4 - 10，130 例（35%）PSA 水平＞10。Gleason 评分≤6 的有 269 例（73%），评分≥7 的有 99 例（27%）。
当排除精囊时，个体患者全剂量照射的直肠总面积减少范围为 5%至 67%（中位数为 44%）。根据剂量体积直方图，照射直肠体积减少至处方剂量 50%时的中位数为 51%（范围：37% - 76%）。膀胱体积减少的中位数为 9%（范围：6% - 15%）。精囊受累发生率为 19%（368 例中的 70 例）。PSA 水平正常（≤4 ng/mL）的患者精囊受累率为 3%（66 例中的 2 例）。PSA 水平在 4 - 10 ng/mL 之间的患者精囊受累率为 8%（126 例中的 10 例）。所有其他病例的精囊受累率至少为 20%，合并率为 33%。以 15%为临界值，确定了两个低风险组：所有 PSA 水平≤4 的患者，以及 PSA 为 4 - 10 且 Gleason 评分≤6 的患者。这些患者占所有患者的 52%（368 例中的 192 例）。总体而言，低风险患者精囊受累发生率为 6%（192 例中的 12 例），而高风险患者为 33%（176 例中的 58 例）（p≤0.001）。
将精囊排除在治疗野之外可显著减少（40% - 50%）直肠受照体积。我们的数据证实，治疗前 PSA 水平和 Gleason 评分可有效用于确定可避免照射精囊的患者亚组。我们建议在所有 PSA 水平≤4 的患者以及 PSA 水平为 4 - 10 且 Gleason 评分≤6 的患者中排除精囊照射。
