Fawaz Ziad Simon, Kazandjian Suzanne, Tsui James M, Devic Dr Slobodan, Lecavalier-Barsoum Magali, Vuong Te, Elakshar Sara, Garant Aurelie, Lavoie Isabelle, Niazi Tamin M
Radiation Oncology, McGill University Health Center, Montreal, CAN.
Radiation Oncology, McGill University/Sir Mortimer B. Davis Jewish General Hospital, Montreal, CAN.
Cureus. 2018 Jul 16;10(7):e2985. doi: 10.7759/cureus.2985.
Background Esophageal cancer treatment requires large radiation fields due to the deep location of the esophagus in the mediastinum and the high incidence of radial spread. There is no optimal radiation technique to ensure appropriate target coverage and minimal dose to all normal structures. Methods Fifteen consecutive cases of locally advanced esophageal cancer treated with radical chemoradiation (CRT) were analyzed. The total prescribed dose was 50.4 Gy in 28 fractions. A total of 60 plans were generated for analysis, including four different methods for each case. Method 1 consisted of a four-field conformal technique; method 2 was a two-plan technique (antero-posterior (AP), postero-anterior (PA), two posterior oblique fields (RPO and LPO)); method 3 was a three-field conformal technique (AP, LPO, RPO); and method 4 was a volumetric modulated arc radiotherapy (VMAT) technique. Dose ratios were calculated using the minimum, maximum, mean, and median doses of methods 2-4 over the dose of method 1. Ratios for the planning target volume (PTV) and to surrounding organs were analyzed. Results The mean PTV dose ratio ranged from 0.994 to 1.048 (SD = 0.01) representing an adequate target coverage for all techniques based on an analysis of variance (ANOVA). For the lungs, method 2 had the lowest lung V20 with a ratio of 0.861 (SD = 0.12), whereas method 3 had the highest with 1.644 (SD = 0.14). For the heart, method 3 had the lowest heart V40 with a mean dose ratio of 0.807 (SD = 0.09), whereas method 2 had the highest with 1.160 (SD = 0.11). For the liver, method 2 had the lowest V30 with a mean ratio of 0.857 (SD = 0.1) whereas method 4 had the highest with 1.672 (SD = 0.48). For the spinal cord, method 3 had the lowest mean dose ratio of 0.559 (SD = 0.09) whereas method 2 had the highest with 1.094 (SD = 0.04). Conclusion The four radiation techniques for esophageal cancer treatment were appropriate for target coverage. Method 2 had the most organ-sparing effect for the lungs and liver, and method 3 for the heart and spinal cord. VMAT did not add any significant sparing. A case-by-case decision should be made based on the patient's comorbidities.
背景 由于食管位于纵隔深处且径向扩散发生率高，食管癌治疗需要大的照射野。目前尚无最佳的放射技术来确保对靶区的适当覆盖以及对所有正常组织的最小剂量。方法 对连续15例接受根治性放化疗（CRT）的局部晚期食管癌病例进行分析。总处方剂量为50.4 Gy，分28次给予。共生成60个计划用于分析，每个病例包括四种不同方法。方法1为四野适形技术；方法2为两野技术（前后（AP）、后前（PA）、两个后斜野（RPO和LPO））；方法3为三野适形技术（AP、LPO、RPO）；方法4为容积调强弧形放疗（VMAT）技术。使用方法2 - 4的最小、最大、平均和中位剂量与方法1的剂量计算剂量比。分析计划靶区（PTV）和周围器官的剂量比。结果 根据方差分析（ANOVA），平均PTV剂量比在0.994至1.048之间（标准差 = 0.01），表明所有技术对靶区的覆盖都足够。对于肺，方法2的肺V20最低，比值为0.861（标准差 = 0.12），而方法3最高，为1.644（标准差 = 0.14）。对于心脏，方法3的心脏V40最低，平均剂量比为0.807（标准差 = 0.09），而方法2最高，为1.160（标准差 = 0.11）。对于肝脏，方法2的V30最低，平均比值为0.857（标准差 = 0.1），而方法4最高，为1.672（标准差 = 0.48）。对于脊髓，方法3的平均剂量比最低，为0.559（标准差 = 0.09），而方法2最高，为1.094（标准差 = 0.04）。结论 食管癌治疗的四种放射技术对靶区覆盖均合适。方法2对肺和肝脏的器官保护作用最大，方法3对心脏和脊髓的器官保护作用最大。VMAT没有增加任何显著的保护作用。应根据患者的合并症进行个案决策。
