Loblaw D A, Wallner K, Dibiase S, Russell K, Blasko J, Ellis W
Radiation Oncology, Princess Margaret Hospital, University Health Network, University of Toronto, Ontario, Canada.
Tech Urol. 2000 Jun;6(2):64-9.
To better define the role of small prostate volume in selecting patients for brachytherapy.
Thirty patients with a transrectal ultrasound (TRUS)-based prostate volumes less than 20 cc were treated at the University of Washington by permanent isotope implantation for prostatic carcinoma. Preimplant TRUS studies were taken at 0.5-cm intervals from the base of the gland to the apex. Planning margins of 1 to 5 mm were added to the prostatic margins, and sources were routinely planned to be placed as much as 5 mm outside of the prostatic margin. The prescription dose was 144 and 115 Gy for full-dose iodine 125 and palladium 103 monotherapy, respectively. For patients receiving supplemental external-beam irradiation, the implant doses were 120 and 90 Gy for 125I and 103Pd, respectively. The morning following the implant, axial computed tomographic (CT) images of the prostate were obtained at 0.5-cm intervals with patients in the supine position. Follow-up ranged from 11 to 28 months (median 21 months).
The median coverage of the postimplant prostate volume by the prescription dose was 92%. To calculate the incidence of source migration, the number of sources placed at the time of implant was compared with the number identified on postimplant CT scan. The median number of sources implanted was 84 (range 65-103) compared to an average of 82 identified postoperatively, which is consistent with a source migration rate of two. A median of 31 sources appeared to be outside of the prostatic margins, as identified on postimplant CT scan (range 14-53). Of the 23 patients contacted at the time of this report, one had developed acute postimplant urinary retention that resolved within 2 weeks of implantation. At last follow-up, patient pre- and postimplant AUA scores were not substantially different, with the median AUA score increasing from 7 (range 2-21) to 8 (range 1-27).
Patients with small prostate volumes appear to have acceptable morbidity and target coverage with prostate brachytherapy. Based on the data reported here, we do not believe that a small prostate volume in itself is a contraindication to brachytherapy.
更好地明确小前列腺体积在前列腺近距离放射治疗患者选择中的作用。
华盛顿大学对30例经直肠超声（TRUS）测量前列腺体积小于20立方厘米的患者进行了永久性同位素植入治疗前列腺癌。植入前的TRUS检查从前列腺底部到尖部每隔0.5厘米进行一次。在前列腺边缘增加1至5毫米的计划边界，并且通常计划将放射源放置在前列腺边缘外多达5毫米处。全剂量碘125和钯103单一疗法的处方剂量分别为144和115戈瑞。对于接受补充外照射的患者，125I和103Pd的植入剂量分别为120和90戈瑞。植入后的第二天早晨，患者仰卧位，以0.5厘米的间隔获取前列腺的轴向计算机断层扫描（CT）图像。随访时间为11至28个月（中位时间21个月）。
处方剂量对植入后前列腺体积的中位覆盖率为92%。为计算放射源迁移率，将植入时放置的放射源数量与植入后CT扫描确定的数量进行比较。植入的放射源中位数为84个（范围65 - 103个），而术后平均确定为82个，这与两个放射源的迁移率一致。植入后CT扫描显示，中位数为31个放射源似乎位于前列腺边缘之外（范围14 - 53个）。在撰写本报告时联系的23例患者中，有1例出现植入后急性尿潴留，在植入后2周内缓解。在最后一次随访时，患者植入前后的美国泌尿外科学会（AUA）评分没有显著差异，AUA评分中位数从7分（范围2 - 21分）增加到8分（范围1 - 27分）。
前列腺体积小的患者接受前列腺近距离放射治疗似乎具有可接受的发病率和靶区覆盖情况。基于此处报告的数据，我们认为前列腺体积小本身并非近距离放射治疗的禁忌证。
