Gao Robert W, Jebastin Judith As, Wenger Doris E, Harmsen William S, Folpe Andrew L, Haddock Michael G, Petersen Ivy A, Ahmed Safia K
1Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, USA.
2Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA.
Radiol Oncol. 2025 Jun 16;59(2):176-182. doi: 10.2478/raon-2025-0032. eCollection 2025 Jun 1.
We retrospectively assessed volumetric response of myxoid liposarcoma (MLPS) with preoperative radiotherapy (RT) and sought to identify disease and treatment characteristics associated with response.
We identified all patients with a histologic diagnosis of MLPS who received preoperative RT from 2013 to 2021 at our institution. We used cone beam computed tomography (CBCT) to assess changes in tumor volume and greatest dimension during treatment. Tumors were contoured on CBCT images prior to treatment and at the end of each week of RT. Percentage change in tumor volume and greatest dimension were calculated based on pre-treatment and final week contours. Patients with tumors incompletely visualized on CBCT were excluded from volume analysis but included on greatest dimension analysis. Magnetic resonance imaging (MRI) was used to evaluate pre- and post-RT radiographic features. Surgical pathology was reviewed to record pathologic characteristics.
Twenty patients met inclusion criteria. Most tumors (18/20) were low grade. The most frequent dose/fractionation scheme was 50 Gy in 25 fractions (16/20), with 3 patients receiving 36 Gy in 18 fractions. Median pre-RT volume and greatest dimension were 120 cc (interquartile range [IQR]: 56-399) and 11.2 cm (IQR: 8.4-14.1), respectively. Median percentage change in volume and greatest dimension were -37% (IQR: -57 to -29) and -10% (IQR: -20 to -7). All evaluable tumors decreased in volume during RT. Between pre- and post-RT MRI, most patients had a decrease in intratumoral (16/20) and peritumoral edema (11/20). Sixteen patients exhibited extensive pathologic response. There were no significant associations between radiographic and pathologic features and volumetric change. Local failure at 3 years was 9% (95% confidence interval: 1-59).
We report significant decreases in MLPS tumor size during preoperative RT. There may be a role for adaptive RT planning to reduce target volumes and minimize RT-associated morbidity.
我们回顾性评估了黏液样脂肪肉瘤（MLPS）术前放疗（RT）后的体积反应，并试图确定与反应相关的疾病和治疗特征。
我们确定了2013年至2021年在我们机构接受术前放疗的所有组织学诊断为MLPS的患者。我们使用锥形束计算机断层扫描（CBCT）评估治疗期间肿瘤体积和最大径的变化。在治疗前和放疗每周结束时，在CBCT图像上勾勒肿瘤轮廓。根据治疗前和最后一周的轮廓计算肿瘤体积和最大径的百分比变化。CBCT上肿瘤显示不完全的患者被排除在体积分析之外，但纳入最大径分析。使用磁共振成像（MRI）评估放疗前后的影像学特征。回顾手术病理以记录病理特征。
20例患者符合纳入标准。大多数肿瘤（18/20）为低级别。最常见的剂量/分割方案是25次分割给予50 Gy（16/20），3例患者接受18次分割给予36 Gy。放疗前体积中位数和最大径分别为120 cc（四分位数间距[IQR]：56 - 399）和11.2 cm（IQR：8.4 - 14.1）。体积和最大径的中位数百分比变化分别为 - 37%（IQR： - 57至 - 29）和 - 10%（IQR： - 20至 - 7）。所有可评估的肿瘤在放疗期间体积均减小。放疗前后MRI对比，大多数患者瘤内（16/20）和瘤周水肿（11/20）减轻。16例患者表现出广泛的病理反应。影像学和病理特征与体积变化之间无显著相关性。3年局部失败率为9%（95%置信区间：1 - 59）。
我们报告了术前放疗期间MLPS肿瘤大小显著减小。自适应放疗计划可能有助于减少靶体积并将放疗相关的发病率降至最低。
