RADIATION THERAPY DOSE ESCALATION FOR PROSTATE CANCER

局限性前列腺癌的最佳治疗方法尚未确定。 而较小的肿瘤可以用可能相等的 根治性前列腺切除术或放射治疗的效果， 放射治疗成为治疗较大肿瘤的主要手段。 然而，放射治疗产生了不太理想的临床长期局部控制。 在这些较大的肿瘤中。此外，相当大比例的患者 临床上看起来被当地控制的人有阳性反应 治疗后每隔18个月或更长时间进行一次活组织检查。因此， 对于巨大的肿瘤，有临床和病理证据表明 放射治疗产生的局部控制率低于最佳水平。 此外，放射后的局部衰竭，无论是临床上还是 经病理检测，似乎对生存有不利影响，强调 需要新的治疗方法。剂量递增，使用三个 立体(3D)，适形放射治疗计划，代表 一种这样的方法，并有可能改善当地控制，同时 将治疗毒性维持在可接受的水平。 I/II期研究建议使用3D适形放射治疗来确定 局部晚期前列腺癌的最大可耐受辐射剂量。 将采用已经开发并已投入使用的3D规划系统 在威斯康星大学使用。它融合了先进的形象 可视化和操纵能力、虚拟模拟、目标 定义、射束和块设计、3D剂量计算、剂量-体积 直方图分析以及门户成像和验证协议。 估计肿瘤控制和治疗概率的生物模型 正常组织并发症，考虑或不考虑影响 包括碎片大小和剂量率。该建模有助于 评估相互竞争的计划。

Optimal treatment for localized prostate cancer has not been determined. While smaller tumors can be managed with what is probably equal effectiveness by either radical prostatectomy or radiation therapy, radiation therapy becomes the mainstay of treatment for larger tumors. Radiation, however, produces suboptimal clinical, long term local control in these larger tumors. In addition a significant proportion of patients who appear clinically to be locally controlled have positive post-treatment biopsies at intervals of eighteen or more months. Thus, for bulky tumors, there is both clinical and pathologic evidence that radiation therapy produces less than optimal rates of local control. Furthermore, local failure after radiation, whether clinically or pathologically detected, appear to adversely affect survival, emphasizing the need for new treatment approaches. Dose escalation, using three dimensional (3D), conformal radiotherapy treatment planning, represents one such approach and has the potential for improving local control while maintaining treatment toxicity at an acceptable level. A phase I/II study is proposed using 3D conformal radiotherapy to define a maximum tolerated radiation dose for locally advanced prostate cancer. A 3D planning system will be employed that has been developed and is in use at the University of Wisconsin. It incorporates advanced image visualization and manipulation capabilities, virtual simulation, target definition, beam and block design, 3D dose computation, dose-volume histogram analyses and portal imaging and verification protocols. Biological modeling that estimates probabilities of tumor control and normal tissue complications, with or without consideration of the impact of fraction size and dose rate, is included. The modeling assists in the evaluation of competing plans.