Department of Radiation Oncology, Cleveland Clinic, Taussig Cancer Institute, Cleveland, Ohio.
Department of Radiation Oncology, Cleveland Clinic, Taussig Cancer Institute, Cleveland, Ohio.
Int J Radiat Oncol Biol Phys. 2020 May 1;107(1):72-78. doi: 10.1016/j.ijrobp.2020.01.009. Epub 2020 Jan 25.
Clinical validation of protocol-specified dosimetric constraints for the proximal bronchial tree (PBT) is limited for central non-small cell lung cancer treated with stereotactic body radiation therapy. We sought to validate Radiation Therapy Oncology Group (RTOG) PBT constraints with a large institutional data set.
Lesions ≤2 cm from the PBT treated with definitive stereotactic body radiation therapy from 2009 to 2016 were identified from a prospective registry of 1462 patients. Every PBT dose and volume combination, ranging from 0 cGy to 8000 cGy in increments of 10 cGy and volumes ranging from 0.03 cm to 50 cm in increments of 0.03 cm, was analyzed. The sensitivity and specificity of these endpoints for identifying pulmonary toxicity were calculated. Pulmonary toxicity was classified as pneumonitis or nonpneumonitis toxicity (NPT) (fistula, stenosis, necrosis, hemoptysis, clinically significant pleural effusion). The optimal dosimetric predictor was chosen by calculation of F-score (highest sensitivity and specificity).
The study included 132 patients, with 26.0-month median follow-up. Eight grade ≥2 NPT (2 grade 5) and 8 grade 2 pneumonitis toxicities were observed. The PBT dosimetric endpoint with the highest F-score for identification of grade 2 to 5 NPT was D0.03cc ≤5000 cGy and that for grade 3 to 5 NPT was D0.33cc ≤4710 cGy, with sensitivity and specificity of 87.5% and 76.6% and 100.0% and 85.7%, respectively. Applying the RTOG 0813 PBT constraints to our data set achieved a sensitivity and specificity of 33.3% and 92.1% for D4cc ≤1800 cGy and 37.5% and 92.7% for D0.03cc ≤5250 cGy for identification of grade 2 to 5 NPT. A PBT dosimetric correlation for pneumonitis toxicity could not be identified.
This novel dosimetric analysis validates current RTOG constraints and emphasizes high-dose, small-volume constraints as better predictors for NPT. We demonstrated that a slightly lower maximum point dose PBT constraint may be optimal for identification of NPT. Validation of these findings in a larger cohort of patients with longer follow-up is necessary.
对于接受立体定向体部放射治疗的中央型非小细胞肺癌，近端支气管树（PBT）的方案指定剂量限制的临床验证受到限制。我们试图用大量机构数据集验证放射治疗肿瘤学组（RTOG）的 PBT 限制。
从 2009 年至 2016 年接受确定性立体定向体部放射治疗的 PBT 病变≤2cm 的患者，从 1462 例患者的前瞻性登记中确定。分析了从 0cGy 到 8000cGy 以 10cGy 为增量，从 0.03cm 到 50cm 以 0.03cm 为增量的每一个 PBT 剂量和体积组合。计算了这些终点识别肺毒性的敏感性和特异性。肺毒性分为放射性肺炎或非放射性肺炎毒性（NPT）（瘘管、狭窄、坏死、咯血、有临床意义的胸腔积液）。通过计算 F 分数（最高的敏感性和特异性）来选择最佳的剂量预测指标。
研究包括 132 例患者，中位随访时间为 26.0 个月。观察到 8 例≥2 级 NPT（2 例 5 级）和 8 例 2 级放射性肺炎毒性。对于识别 2 至 5 级 NPT，D0.03cc≤5000cGy 是具有最高 F 分数的 PBT 剂量终点，对于识别 3 至 5 级 NPT，D0.33cc≤4710cGy 是具有最高 F 分数的 PBT 剂量终点，其敏感性和特异性分别为 87.5%和 76.6%，100.0%和 85.7%。将 RTOG 0813 PBT 限制应用于我们的数据集，对于识别 2 至 5 级 NPT，D4cc≤1800cGy 的敏感性和特异性分别为 33.3%和 92.1%，D0.03cc≤5250cGy 的敏感性和特异性分别为 37.5%和 92.7%。对于放射性肺炎毒性，无法确定 PBT 剂量相关性。
这项新的剂量分析验证了当前的 RTOG 限制，并强调了高剂量、小体积限制作为 NPT 的更好预测指标。我们证明，对于 NPT 的识别，较低的最大点剂量 PBT 限制可能是最佳的。需要在具有更长随访时间的更大患者队列中验证这些发现。
