Supplementary Material for: Hypofractionated Radiotherapy for Anaplastic Thyroid Carcinoma: 15 Years of Experience in a Single Institution

<b><i>Background:</i></b> Anaplastic thyroid carcinoma (ATC) is a rare cancer and has a poor prognosis. Several radiation protocols have been reported, but the results were not satisfactory. <b><i>Objective:</i></b> The aim of this study was to determine the effect of hypofractionated radiotherapy. <b><i>Methods:</i></b> Thirty-three patients who received radiotherapy for ATC between January 2000 and December 2014 were retrospectively included. We defined hypofractionated radiotherapy as a single dose ≥5 Gy. <b><i>Results:</i></b> Nineteen patients were treated with hypofractionated radiotherapy. Twenty-eight patients died, and 27 of those patients died from ATC. Sixteen patients died from distant metastasis and 6 from local recurrence. In the hypofractionated radiotherapy group, local recurrence occurred in 5 patients and 1 of them died from active bleeding from a local tumor. There was local recurrence in 7 patients who received the other protocol, and 5 of them died from asphyxiation, active bleeding, or uncontrollable growth of a local tumor on the neck. The median overall survival (OS) was 5 months. In multivariate analysis, patients who received an equivalent dose in 2-Gy fractions (EQD₂) ≥50 Gy had significantly better OS (<i>p</i> = 0.016). In univariate analysis, patients who received hypofractionated radiotherapy did not have significantly better OS (<i>p</i> = 0.872) or local control (<i>p</i> = 0.090). The χ² test showed that significantly fewer patients died from local recurrence in the hypofractionated radiotherapy group (<i>p</i> = 0.025). <b><i>Conclusions:</i></b> Multivariate analysis showed that an EQD₂ ≥50 Gy resulted in better OS, and hypofractionated radiotherapy decreased the rate of mortality from local recurrence.

**背景：** 间变性甲状腺癌（Anaplastic Thyroid Carcinoma, ATC）是一种罕见的恶性肿瘤，预后极差。目前已有多项放射治疗方案被报道，但疗效均不尽如人意。
**目的：** 本研究旨在探讨大分割放疗（hypofractionated radiotherapy）的临床疗效。
**方法：** 本研究回顾性纳入2000年1月至2014年12月期间共33例接受放射治疗的间变性甲状腺癌患者。本研究将单次照射剂量≥5 Gy定义为大分割放疗。
**结果：** 其中19例患者接受了大分割放疗。最终28例患者死亡，其中27例死于间变性甲状腺癌。16例患者死于远处转移，6例死于局部复发。在大分割放疗组中，5例患者出现局部复发，其中1例因局部肿瘤活动性出血死亡。接受其他放疗方案的患者中，7例出现局部复发，其中5例分别因窒息、活动性出血或颈部局部肿瘤无法控制的进展死亡。本研究的中位总生存期（overall survival, OS）为5个月。多因素分析显示，接受以2 Gy为基准的等效剂量当量（equivalent dose in 2-Gy fractions, EQD₂）≥50 Gy的患者总生存期显著更优（*p*=0.016）。单因素分析显示，接受大分割放疗的患者其总生存期（*p*=0.872）与局部控制率（*p*=0.090）均无显著改善。卡方检验（χ² test）结果显示，大分割放疗组患者因局部复发死亡的比例显著更低（*p*=0.025）。
**结论：** 多因素分析表明，EQD₂≥50 Gy可改善患者总生存期，而大分割放疗可降低因局部复发导致的死亡率。