3026 - The Relationship between Effective Dose to Immune Cells and Vertebral Marrow Dose and Hematologic Toxicity in Neoadjuvant Chemoradiotherapy for Esophageal Squamous Cell Carcinoma

M. Zhang¹, Z. Li², and Y. Yin³; ¹Shandong University Cancer Center,Shandong University, jinan, shandong, China, ²Department of Radiation Oncology Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China, ³Department of Radiation Physics, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China

Purpose/Objective(s): The purpose of this study is to explore the correlation between effective dose to immune cells (EDIC) and vertebral bone marrow dose and hematologic toxicity (HT) during neoadjuvant chemoradiotherapy (nCRT) for esophageal squamous cell carcinoma (ESCC). Materials/

Methods: The research included 106 ESCC patients with clinical stage II-IVa ESCC (according to the eighth edition of the American Joint Committee on Cancer staging system) treated with nCRT. We collected dosimetric parameters, including vertebral body volumes receiving 10–40 Gy (V10, V20, V30, V40) and EDIC, and complete blood counts including white blood cell count (WBC), neutrophil count (NEU), absolute lymphocyte count (ALC), platelet count (PLT), and hemoglobin (HGB) before and during (weekly) nCRT. The cell nadir was defined as the lowest cell count during nCRT. HT were graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Associations of the cell nadir and dosimetric parameters were examined by linear and logistic regression analysis. The receiver operating characteristic (ROC) curves were used to determine the cutoff values for the dosimetric parameters.
Results: During CRT, 81 (76.4%) developed at grade 3–4 lymphopenia, 40 patients (37.3%) developed grade 3–4 leukopenia, 40 patients (37.3%) developed grade 3–4 neutropenia, only 1 patient (0.94%) developed grade 3–4 anaemia, and no patients developed grade 3–4 thrombocytopenia. Patients with EDIC =4.63Gy plus V10 = 140.3 ml were strongly associated with lower risk of grade 3–4 lymphopenia (OR, 0.050; P < 0.001), and patients with EDIC =4.53Gy plus V10 = 100.9 ml were strongly associated with lower risk of grade 3–4 leukopenia (OR, 0.177; P = 0.011), and patients with EDIC =5.79Gy were strongly associated with lower risk of grade 3–4 neutropenia (OR, 0.401; P = 0.031). Kaplan-Meier analysis showed that there was a significant difference among all groups for grade 3–4 lymphopenia, leukopenia, and neutropenia (P < 0.05).
Conclusion: During neoadjuvant radiotherapy for ESCC, the dose of vertebral bone marrow irradiation and EDIC were significantly correlated with G3-4 leukopenia and lymphopenia, and EDIC was again significantly correlated with G3-4 neutropenia. The reduction of vertebral bone marrow irradiation and EDIC was effective in reducing the incidence of hematological toxicity.