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Abstract：
The optimal number of cycles of induction chemotherapy (IC) in locoregionally advanced nasopharyngeal carcinoma (LANPC) remains unresolved. This study aimed to quantitatively assess the changes in gross tumor volumes (GTVs) and to select the most optimal number of IC cycles.
We analyzed 54 patients who received a three-cycle IC before commencing radiotherapy, with the tumor and nodal responses assessed by a CT scan before IC and after each IC cycle. The gross tumor volumes of the nasopharynx primary lesion (GTV_T), involved retropharyngeal lymph node (GTV_RP), and involved cervical lymph node (GTV_N) were contoured on each scan. The volume change following each IC cycle was evaluated with Wilcoxon signed-rank test. The three-dimensional vector displacements of target centers were also calculated and compared.
The volume reductions of GTVs following IC varied across different patients and showed different trends for the three GTV types. GTV_T and GTV_RP did not display further volume reduction after two IC cycles, whereas GTV_N showed monotonic volume decreases. For GTV_T and GTV_RP following the three IC cycles, the total volume reduction relative to the initial volume before IC was 12.0%, 22.5%, and 20.1% and 26.0%, 44.1%, and 42.2%, respectively. In contrast, for GTV_N, continuing volume reduction was observed with a total reduction of 25.3%, 43.2%, and 54.7% following the three cycles, and the reductions were all significant. Average displacements of the GTVs were <1.5 mm in all directions; their average three-dimensional displacements were 2.6, 4.0, and 1.7 mm, respectively. Acceptable toxicity was observed in most patients.
This study supports two cycles of IC before radiotherapy for patients with LANPC if the initial metastatic cervical lymph node volume is not dominating. Otherwise, three cycles of IC is recommended to further reduce the cervical node volume.
We analyzed 54 patients who received a three-cycle IC before commencing radiotherapy, with the tumor and nodal responses assessed by a CT scan before IC and after each IC cycle. The gross tumor volumes of the nasopharynx primary lesion (GTV_T), involved retropharyngeal lymph node (GTV_RP), and involved cervical lymph node (GTV_N) were contoured on each scan. The volume change following each IC cycle was evaluated with Wilcoxon signed-rank test. The three-dimensional vector displacements of target centers were also calculated and compared.
The volume reductions of GTVs following IC varied across different patients and showed different trends for the three GTV types. GTV_T and GTV_RP did not display further volume reduction after two IC cycles, whereas GTV_N showed monotonic volume decreases. For GTV_T and GTV_RP following the three IC cycles, the total volume reduction relative to the initial volume before IC was 12.0%, 22.5%, and 20.1% and 26.0%, 44.1%, and 42.2%, respectively. In contrast, for GTV_N, continuing volume reduction was observed with a total reduction of 25.3%, 43.2%, and 54.7% following the three cycles, and the reductions were all significant. Average displacements of the GTVs were <1.5 mm in all directions; their average three-dimensional displacements were 2.6, 4.0, and 1.7 mm, respectively. Acceptable toxicity was observed in most patients.
This study supports two cycles of IC before radiotherapy for patients with LANPC if the initial metastatic cervical lymph node volume is not dominating. Otherwise, three cycles of IC is recommended to further reduce the cervical node volume.
摘要：
目的：局部晚期鼻咽癌（LANPC）诱导化疗（IC）的最佳周期数尚未确定。这项研究旨在定量评估总肿瘤体积（GTT）的变化，并选择最佳的IC周期数。
方法：我们分析了54例患者在开始放疗前接受了三个周期的IC，在IC之前和每个IC周期后通过CT扫描评估肿瘤和淋巴结反应。鼻咽原发病灶的大体肿瘤体积（GTV_T），咽后受累淋巴结（GTV_RP），每次扫描均对受累颈淋巴结（GTV_N）进行轮廓。用Wilcoxon符号秩检验评估每个IC循环后的体积变化。还计算并比较了目标中心的三维矢量位移。
结果：IC后GTV的体积减少在不同患者中有所不同，并且在三种GTV类型中显示出不同的趋势。GTV_T和GTV_RP在两个IC周期后未显示进一步的音量减小,而GTV_N表现出单调的体积减小。对于三个IC周期之后的GTV_T和GTV_RP，相对于IC之前的初始体积的总体积减少了12.0%，22.5%,20.1%和26.0%，44.1%,和42.2%，分别。相比之下,对于GTV_N，观察到持续的体积减少，总减少25.3%，43.2%,在三个周期之后，54.7%，减少的幅度都很大。GTV在所有方向上的平均位移均<1.5mm；它们的平均三维位移分别为2.6、4.0和1.7mm，分别。在大多数患者中观察到可接受的毒性。
结论：如果初始转移性颈淋巴结体积不占优势，本研究支持LANPC患者放疗前进行两个周期的IC治疗。否则,建议进行三个周期的IC以进一步减少颈淋巴结体积。
方法：我们分析了54例患者在开始放疗前接受了三个周期的IC，在IC之前和每个IC周期后通过CT扫描评估肿瘤和淋巴结反应。鼻咽原发病灶的大体肿瘤体积（GTV_T），咽后受累淋巴结（GTV_RP），每次扫描均对受累颈淋巴结（GTV_N）进行轮廓。用Wilcoxon符号秩检验评估每个IC循环后的体积变化。还计算并比较了目标中心的三维矢量位移。
结果：IC后GTV的体积减少在不同患者中有所不同，并且在三种GTV类型中显示出不同的趋势。GTV_T和GTV_RP在两个IC周期后未显示进一步的音量减小,而GTV_N表现出单调的体积减小。对于三个IC周期之后的GTV_T和GTV_RP，相对于IC之前的初始体积的总体积减少了12.0%，22.5%,20.1%和26.0%，44.1%,和42.2%，分别。相比之下,对于GTV_N，观察到持续的体积减少，总减少25.3%，43.2%,在三个周期之后，54.7%，减少的幅度都很大。GTV在所有方向上的平均位移均<1.5mm；它们的平均三维位移分别为2.6、4.0和1.7mm，分别。在大多数患者中观察到可接受的毒性。
结论：如果初始转移性颈淋巴结体积不占优势，本研究支持LANPC患者放疗前进行两个周期的IC治疗。否则,建议进行三个周期的IC以进一步减少颈淋巴结体积。
