TC36-The Fruit of our Labor: Improvement in Clinical Outcome -
The Example of IMRT and Prostate Cancer
Deborah Kuban, M.D.
M.D. Anderson Cencer Center
Department of Radiation Oncology
Houston, TX 77007
Over the last several years, with advances in computer planning and treatment technology, new techniques for prostate cancer radiation have rapidly evolved. Emphasis has been placed on increasing dose while keeping complication rates as low as possible. To do this, new planning strategies such as Intensity Modulated Radiation Therapy (IMRT) and evaluation methods such as Dose-Volume Histograms (DVH’s) have become necessary. New treatment technology such as Dynamic Multileaf Collimators (DMLC’s) for conformal beam shaping and methods for organ localization were developed simultaneously.
Several studies, both randomized and retrospective, show improvement in PSA disease-free survival with higher doses. Through the use of newer treatment and planning techniques, complication rates have been reduced to acceptably low levels: 5% moderate and 1% severe GI toxicity and 15% moderate and 1% severe GU toxicity. A study completed at M.D. Anderson Cancer Center showed that the volume of rectum irradiated could be decreased by 25-50% and the amount of bladder by 30% by using IMRT.
These very conformal techniques with small margins have necessitated better target localization using B-Mode Acquisition and Targeting (BAT), fiducial marker systems, or CT-linac applications. In addition to organ motion, however, with the prostate, organ deformation is also a significant factor and methods to compensate for this such as image-guided IMRT with daily treatment modification is being explored.
TC36 - 临床疗效的提高：IMRT在前列腺癌治疗中的应用
Deborah Kuban, M.D.
M.D. Anderson Cencer Center
Department of Radiation Oncology
Houston, TX 77007
在过去的几年中，随着计算机计划和治疗技术的发展，前列腺癌放疗新技术进展迅速，治疗的重点放在提高剂量的同时尽量降低发生并发症的几率，为了达到这个目标，出现了新的治疗计划方法，如调强治疗(IMRT)，和评估方法，如剂量体积直方图（DVH），同时还出现了新的治疗技术，如多叶准直器动态调强（DMLC），和器官定位方法。
几项随机性或回顾性的研究表明高剂量可以提高PSA无病生存率。通过使用新的治疗和计划技术，并发症几率已降低到可接受的水平：5%中度和1%重度GI毒性，15%中度和1%重度GU毒性。M.D. Anderson癌症中心的一项研究表明使用IMRT直肠受照的体积减少25-50%，膀胱减少30%。
使用IMRT技术，适形度高，外放边界小，因此需要采用B超（BAT）、标记点系统、或CT-加速器系统来更准确地确定靶区位置。对于前列腺，除了器官运动，器官的变形也很重要，补偿器官变形的方法正在研究中，如采用图像引导的IMRT，每天进行治疗修正。