Department of Radiation Oncology.
Department of Radiology, Netherlands Cancer Institute, Amsterdam, The Netherlands.
Pract Radiat Oncol. 2022 Sep-Oct;12(5):e382-e392. doi: 10.1016/j.prro.2022.03.016. Epub 2022 Apr 20.
Stereotactic body radiation therapy (SBRT) in lung tumors has an excellent local control due to the high delivered dose. Proximity of the proximal bronchial tree (PBT) to the high dose area may result in pulmonary toxicity. Bronchial stenosis is an adverse event that can occur after high dose to the PBT. Literature on the risk of developing bronchial stenosis is limited. We therefore evaluated the risk of bronchial stenosis for tumors central to the PBT and correlated the dose to the bronchi.
Patients with a planning tumor volume (PTV) ≤2 cm from PBT receiving SBRT (8 × 7.5 Gy) between 2015 to 2019 were retrospectively reviewed. Main bronchi and lobar bronchi were manually delineated. Follow-up computed tomography scans were analyzed for bronchial stenosis and atelectasis. Bronchial stenosis was assessed using Common Terminology Criteria for Adverse Events Version 4.0 (CTCAEv4). Patient, tumor, dosimetric factors and survival were evaluated between patients with and without stenosis using uni- and multivariate and Kaplan-Meier analysis.
Fifty-one patients were analyzed with a median age of 70 years and World Health Organization (WHO) performance status ≤1 in 92.2%. Median follow-up was 36 months (interquartile range [IQR], 19.6-45.4) and median overall survival 48 months (IQR 21.5-59.3). In 15 patients (29.4%) bronchial stenosis was observed on follow-up computed tomography scan. Grade 1 stenosis was seen in 21.6% (n = 11), grade 2 in 7.8% (n = 4). No grade ≥3 stenosis was observed. Median time to stenosis was 9.6 months (IQR 4.4-19.2). Patients who developed stenosis had significantly larger gross tumor volume with a median of 19 cm(IQR 7.7-63.2) versus 5.2 cm (IQR 1.7-11.3, P <.01). Prognostic factors in multivariate analysis for stenosis were age (P = .03; odds ratio [OR] 1.1), baseline dyspnea (P = .02 OR 7.7), and the mean lobar bronchus dose (P = .01; OR 1.1).
Low-grade (≤2) lobar bronchial stenosis is a complication in approximately one-third of patients after SBRT for lung tumors with a PTV ≤2 cm from PBT. Prognostic risk factors were age, baseline dyspnea and mean dose on a lobar bronchus.
由于立体定向体放射治疗（SBRT）能够提供高剂量，因此肺部肿瘤的局部控制效果极佳。近端支气管树（PBT）与高剂量区域的接近可能导致肺毒性。支气管狭窄是 PBT 接受高剂量照射后可能发生的不良事件。关于发生支气管狭窄风险的文献有限。因此，我们评估了 PBT 中心肿瘤发生支气管狭窄的风险，并对支气管剂量进行了相关性分析。
回顾性分析了 2015 年至 2019 年间接受 SBRT（8×7.5 Gy）且计划靶区体积（PTV）≤2 cm 与 PBT 接近的患者。手动勾画主支气管和叶支气管。分析随访 CT 扫描结果，评估支气管狭窄和肺不张情况。使用不良事件通用术语标准第四版（CTCAEv4）评估支气管狭窄。使用单变量和多变量分析以及 Kaplan-Meier 分析评估患者、肿瘤、剂量学因素和生存情况。
共分析了 51 例患者，中位年龄为 70 岁，92.2%的患者的世界卫生组织（WHO）体能状态≤1。中位随访时间为 36 个月（四分位距 [IQR]，19.6-45.4），中位总生存期为 48 个月（IQR，21.5-59.3）。在 15 例患者（29.4%）的随访 CT 扫描中观察到支气管狭窄。1 级狭窄占 21.6%（n=11），2 级狭窄占 7.8%（n=4）。未观察到≥3 级狭窄。狭窄中位发生时间为 9.6 个月（IQR，4.4-19.2）。发生狭窄的患者的大体肿瘤体积明显更大，中位数为 19 cm（IQR，7.7-63.2），而 5.2 cm（IQR，1.7-11.3，P<.01）。多变量分析中，狭窄的预后因素为年龄（P=.03；比值比 [OR]，1.1）、基线呼吸困难（P=.02 OR，7.7）和叶支气管平均剂量（P=.01；OR，1.1）。
对于 PTV 与 PBT 之间距离≤2 cm 的肺部肿瘤，SBRT 后约三分之一的患者会出现低级别（≤2 级）的叶支气管狭窄。预后危险因素为年龄、基线呼吸困难和叶支气管平均剂量。
