哪些鼻咽癌患者需要适应性放疗？
Which nasopharyngeal cancer patients need adaptive radiotherapy?
机构信息
Department of Radiation Oncology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
School of Medicine, National Defense Medical Center, Taipei, Taiwan.
出版信息
BMC Cancer. 2018 Dec 10;18(1):1234. doi: 10.1186/s12885-018-5159-y.
BACKGROUND
Adaptive radiotherapy (ART) has potential benefits in patients with nasopharyngeal cancer (NPC). This retrospective study aimed to identify the factors favoring ART.
MATERIALS AND METHODS
Forty NPC patients were retrospectively included in this study. All patients received two-phase, volumetric modulated arc radiotherapy (VMAT) and underwent a second computed tomography (CT) for the phase II ART. We generated phantom, non-ART plans by a hybrid method for comparison with ART plans. A paired t-test was used to evaluate the dose differences between these two plans. A subgroup analysis through a paired t-test was used to evaluate the factors favoring ART.
RESULTS
The second CT images were captured at the median 22 fractions. The median total dose of the planning target volume-one (PTV-1) was 72 Gy, and the phase II dose was 16 Gy. The volumes of the ipsilateral parotid gland (23.2 vs. 19.2 ml, p < 0.000), contralateral parotid gland (23.0 vs. 18.4 ml, p < 0.000), clinical target volume-1 (CTV-1, 32.2 vs. 20.9 ml, p < 0.000), and PTV-1 (125.8 vs. 107.3 ml, p < 0.000) all shrunk significantly between these two CT simulation procedures. Among the nearby critical organs, only the ipsilateral parotid gland displayed significant dose reduction by the ART plan (5.3 vs. 6.0 Gy, p = 0.004). Compared to the phantom plan, the ART could significantly improve the PTV-1 target volume coverage of D (15.4 vs. 12.3 Gy, p < 0.000). Based on the D of PTV-1, the factors of a large initial weight (> 60 kg, p < 0.000), large body mass index (BMI) (> 21.5, p < 0.000), obvious weight loss (> 2.8 kg, p < 0.000), concurrent chemoradiotherapy (p < 0.000), and stages III-IV (p < 0.000) favored the use of ART.
CONCLUSIONS
ART could significantly reduce the mean dose to the ipsilateral parotid gland. ART has dosimetrical benefit for patients with a heavy initial weight, large BMI, obvious weight loss, concurrent chemoradiotherapy, and cancer in stages III-IV.
背景
自适应放疗（ART）在鼻咽癌（NPC）患者中具有潜在的优势。本回顾性研究旨在确定有利于 ART 的因素。
材料和方法
本研究共纳入 40 例 NPC 患者。所有患者均接受两阶段容积调强弧形放疗（VMAT），并在第二阶段进行二次 CT 以进行第二期 ART。我们通过混合方法生成了体模、非 ART 计划，以与 ART 计划进行比较。采用配对 t 检验评估这两种计划之间的剂量差异。采用配对 t 检验进行亚组分析，以评估有利于 ART 的因素。
结果
第二次 CT 图像在中位数 22 个分次时采集。计划靶区 1（PTV-1）的中位总剂量为 72Gy，第二期剂量为 16Gy。同侧腮腺（23.2 比 19.2ml，p<0.000）、对侧腮腺（23.0 比 18.4ml，p<0.000）、临床靶区 1（CTV-1，32.2 比 20.9ml，p<0.000）和 PTV-1（125.8 比 107.3ml，p<0.000）的体积均在两次 CT 模拟过程中明显缩小。在附近的关键器官中，只有同侧腮腺的 ART 计划剂量显著降低（5.3 比 6.0Gy，p=0.004）。与体模计划相比，ART 可以显著提高 PTV-1 靶区 D （15.4 比 12.3Gy，p<0.000）的覆盖率。基于 PTV-1 的 D 值，体重初始值较大（>60kg，p<0.000）、体重指数（BMI）较大（>21.5，p<0.000）、体重明显减轻（>2.8kg，p<0.000）、同期放化疗（p<0.000）和 III-IV 期（p<0.000）是使用 ART 的有利因素。
结论
ART 可以显著降低同侧腮腺的平均剂量。ART 对初始体重较大、BMI 较大、体重明显减轻、同期放化疗和 III-IV 期癌症患者具有剂量优势。
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