Primary tracheobronchial adenoid cystic carcinoma (ACC) is a rare malignancy, so the optimal radiotherapy (RT) dose remains unestablished. We aimed to evaluate the effectiveness of dose-escalated RT for primary tracheobronchial ACC. We retrospectively reviewed 48 patients who had undergone definitive or postoperative RT. Patients classified into the low- and high-dose groups received RT doses <70.0 and ≥70.0 Gy in EQD2, respectively. The primary endpoint was freedom from local progression (FFLP) and overall survival (OS). Throughout the follow-up period, seven patients (14.6%) experienced local progression, while 31 (64.6%) exhibited distant metastasis, most commonly in the lungs. In total, the 5-year FFLP and OS rates were 85.7 and 84.7%, respectively. Multivariate analysis revealed that regional lymph node metastasis at diagnosis and receipt of definitive RT were associated with poorer OS. In the subgroup analysis, the definitive RT group had a 5-year FFLP rate of 33.3 and 78.2% in the low- and high-dose groups (p= 0.065), whereas 5-year OS rates were 66.7 and 79.0%, respectively (p= 0.022). Four patients (8.3%) experienced Grade 3 toxicity with tracheal or main bronchus stenosis. Dose-escalated RT with conventional fractionation may be effective in patients with tracheobronchial ACC, especially for a definitive aim.
原发性气管支气管腺样囊性癌是一种罕见恶性肿瘤，其最佳放疗剂量尚未明确。本研究旨在评估剂量递增放疗对原发性气管支气管腺样囊性癌的疗效。我们回顾性分析了48例接受根治性或术后放疗的患者，根据等效生物剂量将患者分为低剂量组（<70.0 Gy）和高剂量组（≥70.0 Gy）。主要研究终点为无局部进展生存期和总生存期。随访期间，7例患者（14.6%）出现局部进展，31例（64.6%）发生远处转移（最常见为肺转移）。总体5年无局部进展生存率和总生存率分别为85.7%和84.7%。多变量分析显示，诊断时存在区域淋巴结转移及接受根治性放疗与较差的总生存期相关。亚组分析表明，根治性放疗组中低剂量组与高剂量组的5年无局部进展生存率分别为33.3%和78.2%（p=0.065），5年总生存率分别为66.7%和79.0%（p=0.022）。4例患者（8.3%）出现3级毒性反应（气管或主支气管狭窄）。常规分割的剂量递增放疗对气管支气管腺样囊性癌患者可能具有疗效，尤其适用于根治性治疗目的。
Dose-Escalated Radiotherapy for Primary Tracheobronchial Adenoid Cystic Carcinoma
肿瘤(癌症)患者之家