Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta Georgia, USA.
Cancer. 2013 Apr 15;119(8):1578-85. doi: 10.1002/cncr.27934. Epub 2012 Dec 27.
The use of radiation therapy (RT) "cone-down" boost to reduce high-dose treatment volumes according to tumor response to induction chemotherapy in patients with pediatric rhabdomyosarcoma (RMS) may reduce treatment morbidity, yet the impact on tumor control is unknown.
Fifty-five children, including 18 (33%) with parameningeal (PM) RMS and 37 (67%) with non-PM RMS, who received definitive treatment with chemotherapy and RT from April 2000 through January 2010 were retrospectively reviewed.
In total, 28 patients (51%) received a cone-down boost. The high-dose boost volume was reduced by a median of 56% of the initial target volume (range, 5%-91%). The median time to initiating RT was 3 weeks for patients with PM RMS and 16 weeks for patients with non-PM RMS (P < .001). After a median follow-up of 41 months, local failure occurred in 5 patients (9%), including 2 patients who received a cone-down boost, and there were no marginal failures. Twelve patients (67%) with PM RMS had intracranial tumor extension. In this subgroup, 4 patients (30%) who received a cone-down boost and had ≥ 3 weeks between chemotherapy and RT initiation experienced leptomeningeal failure as their first site of disease progression, and a delayed time to RT initiation was associated with decreased survival (P = .055)
A cone-down boost allowed for significant reductions in high-dose RT treatment volume while maintaining excellent tumor control in most patients. However, in the subset of patients with PM RMS and intracranial tumor extension, early RT initiation and wider margin RT to cover adjacent areas at high risk for meningeal extension may be more important for adequate disease control.
在儿科横纹肌肉瘤（RMS）患者中，根据诱导化疗的肿瘤反应，使用放射治疗（RT）“锥形降低”来减少高剂量治疗体积，可能会降低治疗的发病率，但对肿瘤控制的影响尚不清楚。
回顾性分析了 2000 年 4 月至 2010 年 1 月期间接受化疗和 RT 确定性治疗的 55 名儿童患者的资料，其中 18 例（33%）为脑脊膜外（PM）RMS，37 例（67%）为非 PM RMS。
共有 28 例（51%）患者接受了锥形降低的剂量增加。高剂量剂量增加体积减少了初始靶体积的中位数为 56%（范围，5%-91%）。PM RMS 患者的中位 RT 开始时间为 3 周，非 PM RMS 患者的中位 RT 开始时间为 16 周（P<.001）。中位随访 41 个月后，5 例（9%）患者发生局部失败，其中 2 例患者接受了锥形降低的剂量增加，无边缘失败。12 例（67%）PM RMS 患者有颅内肿瘤延伸。在这个亚组中，4 例（30%）接受锥形降低剂量增加且化疗和 RT 起始之间间隔 ≥ 3 周的患者经历了脑膜失败作为疾病进展的首发部位，RT 起始延迟与生存时间缩短相关（P =.055）。
锥形降低剂量增加允许显著减少高剂量 RT 治疗体积，同时在大多数患者中保持良好的肿瘤控制。然而，在 PM RMS 和颅内肿瘤延伸的患者亚组中，早期 RT 起始和更宽的边缘 RT 以覆盖高风险的脑膜延伸相邻区域，可能对充分控制疾病更为重要。
