Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
Department of Radiology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts.
Int J Radiat Oncol Biol Phys. 2019 Mar 1;103(3):654-668. doi: 10.1016/j.ijrobp.2018.10.006. Epub 2018 Oct 15.
Radiation-related toxicity in nasopharyngeal carcinoma (NPC) is common. There are no well-established guidelines for clinical target volume (CTV) delineation with long-term follow-up. Current consensus continues to rely heavily on bony landmarks and fixed margins around the gross tumor volume (GTV), an approach used to define fields in the conventional 2- and 3-dimensional radiation therapy era.
We retrospectively evaluated patients with newly diagnosed nonmetastatic NPC treated with definitive radiation therapy using a technique of CTV delineation based on individual tumor extent and the orderly stepwise pattern of tumor spread. Dosimetric comparisons were made between national protocol HN001 and our contouring strategies on a representative early- and advanced-stage NPC. The primary endpoints were patterns of failure and local control; secondary endpoints included regional control and survival, estimated using the Kaplan-Meier method.
Between 1999 and 2013, 73 patients (88% with stage 3-4 disease) were treated with median follow-up of 90 months for surviving patients. Median dose to GTV was 70 Gy. Four patients developed local recurrence and 1 patient developed regional recurrence. All locoregional recurrences occurred within the high-dose GTV. The 5-year local control, regional control, and overall survival was 94% (95% confidence interval [CI], 85%-98%), 99% (95% CI, 90%-100%), and 84% (95% CI, 73%-91%), respectively. Compared with HN001, our contouring strategy resulted in 62% and 36% reduction in CTV for T1 and T4 disease, respectively. In the T1 tumor, the reduction of doses to the contralateral parotid, optic nerve, and cochlea were 54%, 50%, 34% respectively. In the T4 case, there was a decrease of optic chiasm dose of 46% and contralateral optic nerve of 37%. There were 10 grade 3 toxicities. There was no grade 2 or higher xerostomia and no grade 4/5 toxicity.
Our long-term experience with individualized CTV delineation based on stepwise patterns of spread results in excellent local control, with no recurrence outside the GTV.
鼻咽癌（NPC）的放射性相关毒性很常见。对于长期随访的临床靶区（CTV）勾画，尚无完善的指南。目前的共识仍然主要依赖于肿瘤大体体积（GTV）的骨性标志和固定边界，这是在传统二维和三维放射治疗时代用于定义射野的方法。
我们回顾性评估了 73 例接受根治性放射治疗的初诊非转移性 NPC 患者，这些患者采用了一种基于肿瘤个体范围和肿瘤有序渐进式扩散模式的 CTV 勾画技术。我们比较了国家方案 HN001 和我们勾画策略在代表早期和晚期 NPC 病例中的剂量学差异。主要终点为失败模式和局部控制；次要终点包括局部区域控制和生存，采用 Kaplan-Meier 方法进行估计。
1999 年至 2013 年，73 例患者（88%为 3-4 期疾病）接受了中位随访 90 个月的治疗，所有存活患者的中位 GTV 剂量为 70Gy。4 例患者发生局部复发，1 例患者发生区域复发。所有局部区域复发均发生在高剂量 GTV 内。5 年局部控制、区域控制和总生存率分别为 94%（95%置信区间 [CI]，85%-98%）、99%（95%CI，90%-100%）和 84%（95%CI，73%-91%）。与 HN001 相比，我们的勾画策略使 T1 和 T4 疾病的 CTV 分别减少了 62%和 36%。在 T1 肿瘤中，对侧腮腺、视神经和耳蜗的剂量分别减少了 54%、50%和 34%。在 T4 病例中，视交叉剂量降低了 46%，对侧视神经剂量降低了 37%。有 10 例 3 级毒性。没有 2 级或更高级别的口干症，也没有 4/5 级毒性。
我们基于肿瘤扩散顺序的个体化 CTV 勾画的长期经验带来了出色的局部控制效果，且 GTV 外无复发。
