Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey.
Department of Biostatistics, School of Public Health, Rutgers University, Piscataway, New Jersey; Biometrics Division, Rutgers Cancer Institute of New Jersey, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey.
Pract Radiat Oncol. 2019 Jan;9(1):e74-e82. doi: 10.1016/j.prro.2018.08.007. Epub 2018 Aug 23.
This study aimed to investigate the association between target volume margins and clinical outcomes for patients with inoperable non-small cell lung cancer (NSCLC) treated with concurrent chemoradiation therapy.
We reviewed the records of 82 patients with inoperable NSCLC treated between 2009 and 2016 with concurrent chemoradiation. All patients received positron emission tomography-based treatment planning, 4-dimensional computed tomography simulation to define an internal target volume, and daily cone beam computed tomography. We quantified variations in target volume margins with a margin deviation index (MDI), calculated as the percentage change in equivalent uniform dose between the original planning target volume (PTV) and a standard reference PTV 10 mm beyond the original gross tumor volume, consistent with the minimum margins mandated by recent NSCLC trials. Greater MDIs equated to smaller effective target volume margins. We dichotomized patients by the upper tercile MDI value (5.8%). Endpoints included time to locoregional progression and time to grade ≥ 3 radiation esophagitis (RE3) or radiation pneumonitis (RP3), modelled with the Fine-Gray method.
Median follow-up was 37.8 months (range, 5.9-58.1 months). Larger MDIs correlated with smaller clinical target volume (CTV) + PTV margins, larger gross tumor volumes, later treatment year, and intensity modulated radiation therapy use. The risk of locoregional progression did not differ for MDI ≥5.8% versus <5.8% (adjusted hazard ratio: 0.88; P = .76), but the risk of RE3 or RP3 was decreased for MDI ≥5.8% (adjusted hazard ratio: 0.27; P = .027). Patients with MDI ≥5.8% were treated with smaller CTV + PTV margins (median, 5.6 vs 8 mm; P < .0001) and a marginally lower volume of esophagus receiving ≥50 Gy (median, 31.1% vs 35.3%; P = .069).
Smaller margins were used for larger tumors but were not associated with an increase in locoregional failures. Additional studies could clarify whether smaller margins, when used alongside modern radiation therapy techniques, decrease treatment-related toxicity for inoperable NSCLC.
本研究旨在探讨对于接受同期放化疗的不可手术非小细胞肺癌（NSCLC）患者，靶区边界与临床结局之间的关系。
我们回顾了 2009 年至 2016 年间接受同期放化疗的 82 例不可手术 NSCLC 患者的病历。所有患者均接受基于正电子发射断层扫描的治疗计划制定、4 维计算机断层扫描模拟以确定内部靶区以及每日锥形束计算机断层扫描。我们使用剂量学均匀性指数（MDI）来量化靶区边界的变化，MDI 计算为原始计划靶区（PTV）与原始大体肿瘤体积之外 10mm 的标准参考 PTV 之间等效均匀剂量的百分比变化，与最近 NSCLC 试验规定的最小边界一致。较大的 MDI 值表示有效的靶区边界较小。我们根据 MDI 的上三分位数（5.8%）将患者分为两组。终点包括局部区域进展时间和 3 级及以上放射性食管炎（RE3）或放射性肺炎（RP3）时间，采用 Fine-Gray 方法建模。
中位随访时间为 37.8 个月（范围：5.9-58.1 个月）。较大的 MDI 值与较小的临床靶区（CTV）+PTV 边界、较大的大体肿瘤体积、较晚的治疗年份以及调强放疗的使用相关。MDI≥5.8%与 MDI<5.8%的患者局部区域进展风险无差异（调整后的危险比：0.88；P=0.76），但 MDI≥5.8%的患者发生 RE3 或 RP3 的风险降低（调整后的危险比：0.27；P=0.027）。MDI≥5.8%的患者接受的 CTV+PTV 边界较小（中位数：5.6 与 8mm；P<0.0001），接受≥50Gy 的食管体积也略小（中位数：31.1%与 35.3%；P=0.069）。
对于较大的肿瘤，使用较小的边界，但与局部区域失败的增加无关。进一步的研究可以阐明在使用现代放疗技术的情况下，较小的边界是否会降低不可手术 NSCLC 的治疗相关毒性。
