诱导化疗对局部晚期鼻咽癌IMRT靶区及剂量学影响

Influence of induction chemotherapy on target radiotherapy for locally advanced nasopharyngeai Xuping volume and dosimetry of intensity modulated carcinoma

随着诱导化疗的进行，靶区大小、周围OAR剂量分布、原靶区剂量适形性都会发生变化，临床上该怎样合理设计放疗计划呢？国际上支持诱导化疗后放疗，但倡导按诱导化疗前GTV进行靶区勾画并剂量不降低，该观点缺乏循证医学依据。而国内相关专家学者则从靶区缩小，减少靶区高剂量区体积、提高靶区均匀剂量覆盖，降低周围OAR剂量，提高剂量适形性等方面阐明了诱导化疗后再计划的优越性，但其远期疗效与获益目前还无客观数据。另外．诱导化疗后再计划应该以什么样方案勾画靶区、怎样确定剂量分配也还没达成共识，需要继续探索。

As induction chemotherapy goes on, target volume, dose distribution in the surrounding organs at risk （ OARs ） , and target dose conformity all change. Therefore, the question is how to develop reasonable radiotherapy plans in clinical practice. Induction chemotherapy followed by radiotherapy is commonly used around the world, but it is recommended to delineate the target volume based on the gross tumor volume before induction chemotherapy and not to reduce the dose. This point of view lacks the basis of evidence-based medicine. The experts and scholars in China clarify the advantages of radiotherapy plans after induction chemotherapy from the aspects of reducing the target volume, reducing the volume of high-dose region in the target volume, increasing the uniform dose coverage in target volume, reducing dose to OARs, and increasing dose conformity. However, at present, there are no objective data on its long-term efficacy and benefit. Besides, no consensus has been reached on how to delineate the target volume and determine the dose distribution after induction chemotherapy, and further studies are needed.