Department of Radiotherapy, The Netherlands Cancer Institute, Amsterdam, the Netherlands.
Department of Radiotherapy, The Netherlands Cancer Institute, Amsterdam, the Netherlands.
Pract Radiat Oncol. 2019 Mar;9(2):115-122. doi: 10.1016/j.prro.2018.11.001. Epub 2018 Nov 14.
Many authors suggest that extremity soft tissue sarcomas (ESTS) do not change significantly in size during preoperative radiation therapy (RT). This cone beam computed tomography study investigates the justification to deliver the entire course with 1 initial RT plan by observing anatomic changes during RT.
Between 2015 and 2017, 99 patients with ESTS were treated with either curative (n = 80) or palliative intent (n = 19) with a regimen of at least 6 fractions. The clinical target volume to planning target volume margin was 1 cm. Action levels were assigned by radiation technicians. An extremity contour change of >1 cm and/or tumor size change >0.5 cm required a physician's action before the next fraction.
A total of 982 cone beam computed tomography logfiles were studied. In 41 of 99 patients, the dose coverage of the initial treatment plan was fully satisfactory throughout the RT course. However, action levels were observed in 58 patients (59%). In 41 of these 58 patients, a contour increase of 5 to 23 mm was noted (29 tumor size increase only, 3 extremity contour increase, and 9 both). In 21 of 58 patients, a decrease of 5 to 33 mm was observed (20 tumor size decrease only and 1 tumor size decrease and extremity contour decrease). In 4 cases, contours initially increased and subsequently decreased. In 33 of 41 patients with increasing contours, the dose distribution adequately covered gross tumor volume because of the 1 cm planning target volume margin applied. For the remaining 8 patients (8%), the plan needed to be adapted.
ESTS volumes may change substantially during RT in 59% of all patients, leading to plan adaptations resulting from increased volumes in 8%. Daily critical observation of these patients is mandatory to avoid geographic misses because of increases in size and overdosing of normal tissues when masses shrink.
许多作者认为，在术前放疗（RT）期间，肢体软组织肉瘤（ESTS）的大小不会显著变化。本锥形束 CT 研究通过观察 RT 期间的解剖变化，探讨了使用 1 个初始 RT 计划完成整个疗程的合理性。
2015 年至 2017 年间，99 例 ESTS 患者接受了根治性（n=80）或姑息性（n=19）治疗，方案至少包括 6 个分次。临床靶区到计划靶区的边缘为 1cm。剂量技术员分配了行动水平。在下次分次治疗前，如果肢体轮廓变化超过 1cm 和/或肿瘤大小变化超过 0.5cm，则需要医生采取行动。
共研究了 982 个锥形束 CT 日志文件。在 99 例患者中，有 41 例患者在整个 RT 过程中，初始治疗计划的剂量覆盖完全令人满意。然而，在 58 例患者（59%）中观察到了行动水平。在这 58 例患者中，有 41 例患者的轮廓增加了 5 到 23mm（仅 29 例肿瘤大小增加，3 例肢体轮廓增加，9 例两者都有）。在 58 例患者中，有 21 例观察到减少了 5 到 33mm（仅 20 例肿瘤大小减少，1 例肿瘤大小减少和肢体轮廓减少）。在 4 例患者中，轮廓最初增加，随后减少。在 41 例轮廓增大的患者中，由于应用了 1cm 的计划靶区边缘，大部分肿瘤体积的剂量分布得到了充分覆盖。对于其余 8 例患者（8%），需要调整计划。
在所有患者中，59%的 ESTS 体积可能会在 RT 期间发生显著变化，导致因体积增加而需要调整计划的情况增加了 8%。对于这些患者，必须每天进行关键观察，以避免因肿块缩小导致的尺寸增加和正常组织过度剂量。
