Sandler H M, McLaughlin P W, Ten Haken R K, Addison H, Forman J, Lichter A
University of Michigan Medical Center, Department of Radiation Oncology, Ann Arbor, USA.
Int J Radiat Oncol Biol Phys. 1995 Nov 1;33(4):797-801. doi: 10.1016/0360-3016(95)00219-7.
Three dimensional conformal radiotherapy (3D CRT) may provide a technique to increase the dose delivered to target tissues while sparing uninvolved normal structures. To evaluate the role of 3D treatment in reducing the treatment toxicity, we analyzed the chronic rectal morbidity observed in a large group of patients undergoing radiotherapy for prostate cancer.
From 1987 through 1992, 721 prostate cancer patients were treated with 3D CRT at the University of Michigan or Providence Hospital. All had axial computed tomography (CT) specifically for RT planning, multiple structures contoured on the axial images, and beam's-eye-view conformal beams edited to provide 3D dose coverage. Using current American Joint Commission (AJCC) staging, 537 patients had T1-T2 tumors, 123 had T3-T4 tumors, and 60 were treated postprostatectomy. Pelvic lymph nodes were treated in 462 patients. Prostate boosts were delivered with four-field axial, six-field axial, or four-field oblique, nonaxial fields. The median dose was 68.40 Gy (range 59.4-80.4). Median follow-up was 20.4 months; 175 were followed more than 3 years. All complications have been graded conservatively using the RTOG system.
Using a Cox proportional hazard's model, patient age, T-stage, prescribed dose, pelvic treatment, and boost technique were analyzed. The factor most strongly related to risk of morbidity was dose (p = 0.05); however, the boost technique was also related: the four-field oblique field had the lowest relative risk. Most episodes of rectal morbidity have been mild: 82 Grade 1 or 2. There have been only 14 more serious complications including 12 Grade 3 and 2 Grade 4. The actuarial risk of a Grade 3 or 4 complication is 3% at 3 and 5 years.
A very small proportion of patients treated with 3D CRT had significant rectal morbidity related to RT, supporting the use of conformal treatment planning and dose delivery as a mechanism to minimize complications in the treatment of prostate cancer.
三维适形放射治疗（3D CRT）可提供一种技术，在保护未受累正常结构的同时增加给予靶组织的剂量。为评估三维治疗在降低治疗毒性方面的作用，我们分析了一大组接受前列腺癌放疗患者中观察到的慢性直肠发病率。
1987年至1992年期间，密歇根大学或普罗维登斯医院对721例前列腺癌患者进行了三维适形放射治疗。所有患者均进行了专门用于放疗计划的轴向计算机断层扫描（CT），在轴向图像上勾画了多个结构，并编辑了射野视角适形射野以提供三维剂量覆盖。根据当前美国联合委员会（AJCC）分期，537例患者为T1 - T2期肿瘤，123例为T3 - T4期肿瘤，60例为前列腺切除术后接受治疗。462例患者对盆腔淋巴结进行了治疗。前列腺加量照射采用四野轴向、六野轴向或四野斜向非轴向野。中位剂量为68.40 Gy（范围59.4 - 80.4）。中位随访时间为20.4个月；175例随访时间超过3年。所有并发症均按照美国放射肿瘤学协作组（RTOG）系统进行了保守分级。
使用Cox比例风险模型，对患者年龄、T分期、处方剂量、盆腔治疗和加量照射技术进行了分析。与发病风险最密切相关的因素是剂量（p = 0.05）；然而，加量照射技术也有关系：四野斜向野的相对风险最低。大多数直肠发病情况较轻：82例为1级或2级。仅有14例更严重的并发症，包括12例3级和2例4级。3年和5年时3级或4级并发症的精算风险为3%。
接受三维适形放射治疗的患者中，只有极少数患者出现与放疗相关的严重直肠发病率，这支持了使用适形治疗计划和剂量给予作为减少前列腺癌治疗并发症的一种机制。
