Cardiac substructure-guided radiotherapy planning for esophageal cancer: a novel strategy for cardiotoxicity...

A novel method was proposed to protect the sensitive cardiac substructures in esophageal cancer patients and reduce the risk of cardiotoxicity.

A retrospective study was conducted on 20 patients with esophageal cancer. For each patient, a conventional clinical plan (c-IMRT) and a plan to protect sensitive cardiac substructures (p-IMRT) were designed. Dosimetric parameters of the two plans were calculated. The tumor control probability (TCP) of the target and the normal tissue complication probability (NTCP) of normal tissue were compared between two plans. Paired sample t test and Wilcoxon signed-rank test were used in to assess significant differences (p < 0.05) between data set.

In the p-IMRT plans, the dose covering 2% of planning target volume (PTV) (D2) and homogeneity index (HI) of PTV were significantly higher than those in c-IMRT plans, D98 of PTV was significantly lower than that in c-IMRT plans. No significant differences in other indicators. The percentages of total lung volume receiving ≥ 5 Gy and 20 Gy (V5 and V20), as well as the maximum dose (Dmax) to the spinal cord, were comparable between the p-IMRT and c-IMRT plans. Compared with the c-IMRT plans, the p-IMRT plans significantly reduced the dose of six sensitive cardiac substructures, include left ventricle (LV), pulmonary artery (PA), left main artery (LMA), left anterior descending artery (LAD), left circumflex (LCX) and right coronary artery (RCA). Mean dose (Dmean) of LMA, LAD, LCX and RCA decreased by 23.41%, 45.45%, 27.84% and 28.18%, respectively. Dmax of LCX and RCA decreased by 12.42%, 27.32%, 22.03% and 24.62%. Notably, the NTCP of the heart in the p-IMRT plans (0.10 ± 0.11‰) was significantly lower than that in c-IMRT plans (0.13 ± 0.09‰).

The research shows that the novel method for protecting sensitive cardiac substructures can effectively reduce the dose of cardiac substructures without significantly increasing the dose of other organs at risk (OARs). By delineating sensitive cardiac substructures, it could significantly decrease the NTCP of the heart while increasing TCP of the target, thereby improving the quality of clinical plans.