Li Longhao, Yi Xin, Cui Haixia, Zhao Xuemei, Dang Jun, Jiang Qingfeng, Li Ying
Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
Department of Oncology, The Dazu District People's Hospital, Chongqing, China.
Front Oncol. 2020 Nov 23;10:545892. doi: 10.3389/fonc.2020.545892. eCollection 2020.
As an emerging clinical problem, locally advanced drug-resistant gastrointestinal stromal tumors (LADRGISTs) has relatively few therapeutic schemes. Although radiotherapy is not often considered for GISTs, it could be a valuable contributing modality. The aim of our study is to explore a safe and effective radiation regimen for LADR-GISTs.
Three patients with LADR-GISTs were treated with simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT) plans. In the SIB-IMRT plans, gross target volume (GTV) was divided into GTV-outer, GTV-mid, and GTV-center. And the prescribed dose of planning gross target volume (PGTV) and GTV-outer were both set to 50.4 Gy in 28 fractions. GTV-mid and GTV-center were simultaneously boosted to 60-62 Gy and 62-64 Gy respectively. For comparison purposes, conventional IMRT (Con-IMRT) plans with uniform dose distribution were generated for same optimization objectives without a dose boost to GTV-mid and GTV-center. All plans were optimized to make sure that deliver at least 95% of the prescription dose was delivered to PGTV. Isodose distribution, dose profiles, conformity indexes (CIs), monitor units (MUs), and dose volume histogram (DVH) was evaluated for each individual patient. After the three patients were treated with SIB-IMRT plans, the relative changes in the tumor size and CT values by CT scanning were also tracked.
Compared with Con-IMRT plans, SIB-IMRT plans saw a significant increase from D to D of the GTV. With steeper dose gradients in the dose profiles, SIB-IMRT plans had GTV-mid and GTV-center accumulated with higher dose mainly by delivering extra 93 MUs in average. However, there was no significant difference in CIs and organs at risks (OARs) DVH. The relative changes in tumor size and CT values of the three patients in follow up were up to the Choi criteria and the three patients were all assessed as partial response.
The proposed SIB-IMRT may be a potential technique for achieving objective response and prolonging survival of selected GISTs patients.
作为一个新出现的临床问题，局部晚期耐药胃肠道间质瘤（LADRGISTs）的治疗方案相对较少。虽然胃肠道间质瘤通常不考虑放疗，但它可能是一种有价值的辅助治疗方式。我们研究的目的是探索一种针对LADR - GISTs安全有效的放疗方案。
对3例LADR - GISTs患者采用同步整合加量调强放疗（SIB - IMRT）计划进行治疗。在SIB - IMRT计划中，大体肿瘤体积（GTV）分为GTV - 外周、GTV - 中间和GTV - 中心。计划大体肿瘤体积（PGTV）和GTV - 外周的处方剂量均设定为50.4 Gy，分28次给予。GTV - 中间和GTV - 中心分别同步加量至60 - 62 Gy和62 - 64 Gy。为作比较，针对相同的优化目标生成了剂量分布均匀的常规IMRT（Con - IMRT）计划，未对GTV - 中间和GTV - 中心进行剂量加量。所有计划均进行优化，以确保至少95%的处方剂量能给予PGTV。对每位患者评估等剂量分布、剂量曲线、适形指数（CIs）、监测单位（MUs）和剂量体积直方图（DVH）。3例患者采用SIB - IMRT计划治疗后，还通过CT扫描追踪肿瘤大小和CT值的相对变化。
与Con - IMRT计划相比，SIB - IMRT计划中GTV的D到D有显著增加。由于剂量曲线中的剂量梯度更陡，SIB - IMRT计划主要通过平均额外增加93个MU使GTV - 中间和GTV - 中心累积更高剂量。然而，CIs和危及器官（OARs）的DVH没有显著差异。3例患者随访时肿瘤大小和CT值的相对变化达到Choi标准，3例患者均评估为部分缓解。
所提出的SIB - IMRT可能是实现部分胃肠道间质瘤患者客观缓解和延长生存期的一种潜在技术。
