Steponavičienė Rita, Jonušas Justinas, Griškevičius Romualdas, Venius Jonas, Cicėnas Saulius
External Beam Radiotherapy Department, National Cancer Institute, Santariskiu Str. 1, LT-08406 Vilnius, Lithuania.
Vilnius University Hospital Santaros Klinikos, Santariskiu Str. 2, LT-08410 Vilnius, Lithuania.
Medicina (Kaunas). 2021 Mar 31;57(4):320. doi: 10.3390/medicina57040320.
The real impact of ionizing radiation on the heart and poorer overall survival for patients with non small cell lung cancer (NSCLC) remains unclear. This study aims to determine the safe dose constraints to the heart's subregions that could prevent patients' early non-cancerous death and improve their quality of life. A retrospective cohort study was performed containing 51 consecutive patients diagnosed with stage III NSCLC and treated using 3D, Intensity-modulated radiation therapy (IMRT), and Volumetric modulated arc therapy (VMAT) radiotherapy. For a dosimetric analysis, these structures were chosen: heart, heart base (HB), and region of great blood vessels (GBV). Dose-volume histograms (DVH) were recorded for all mentioned structures. Maximum and mean doses to the heart, HB, the muscle mass of the HB, and GBV were obtained. V10-V60 (%) parameters were calculated from the DVH. After performed statistical analysis, logistic regression models were created, and critical doses calculated. The critical dose for developing a fatal endpoint for HB was 30.5 Gy, while for GBV, it was 46.3 Gy. Increasing the average dose to the HB or GBV by 1 Gy from the critical dose further increases the possibility of early death by 22.0% and 15.8%, respectively. We suggest that the non-canonical sub-regions of the heart (HB and GBV) should be considered during the planning stage. Additional constraints of the heart subregions should be chosen accordingly, and we propose that the mean doses to these regions be 30.5 Gy and 46.3 Gy, respectively, or less. Extrapolated DVH curves for both regions may be used during the planning stage with care.
电离辐射对心脏的实际影响以及非小细胞肺癌（NSCLC）患者总体生存率较低的情况仍不明确。本研究旨在确定心脏各亚区域的安全剂量限制，以预防患者早期非癌性死亡并改善其生活质量。进行了一项回顾性队列研究，纳入了51例连续诊断为III期NSCLC并接受三维适形放疗（3D）、调强放疗（IMRT）和容积调强弧形放疗（VMAT）的患者。为进行剂量学分析，选择了以下结构：心脏、心底（HB）和大血管区域（GBV）。记录了所有上述结构的剂量体积直方图（DVH）。获取了心脏、HB、HB肌肉质量和GBV的最大剂量和平均剂量。从DVH计算V10-V60（%）参数。进行统计分析后，创建了逻辑回归模型并计算了临界剂量。HB发生致命终点的临界剂量为30.5 Gy，而GBV为46.3 Gy。从临界剂量将HB或GBV的平均剂量增加1 Gy，分别会使早期死亡的可能性进一步增加22.0%和15.8%。我们建议在计划阶段应考虑心脏的非典型亚区域（HB和GBV）。应相应地选择心脏亚区域的额外限制条件，并且我们建议这些区域的平均剂量分别为30.5 Gy及以下和46.3 Gy及以下。在计划阶段可谨慎使用这两个区域的外推DVH曲线。
