1483P Tumor volume dynamic change during radiotherapy as a potential prognostic factor for short-term effect in patients with esophageal squamous cell carcinoma

Abstract

To investigate the tumor volume dynamic change on short-term effect (STE) in esophageal squamous cell carcinoma (ESCC) patients underwent definitive radiotherapy. All data were retrospectively collected from 418 ESCC patients who received radiotherapy at our institution between 2015 and 2019. The tumor volume change rate (TVCR) was defined as follows: TVCR = 1 – [gross tumor volume (GTV) at the repositioned treatment planning)] / (GTV at the initial treatment planning). STE was assessed by an imaging deputy chief physician and a radiotherapy deputy chief physician according to computed tomography and esophagography before and at 1 month after radiotherapy according to Response Evaluation Criteria in Solid Tumor. Chi square test was used to compare the clinic characteristics in different TVCR groups, and the difference between primary GTV (GTVp) and repositioned GTV (GTVr) was compared using Wilcoxon’s sign rank test. Logistic regression analysis and spearman correlation was performed. At 1 month after radiotherapy, 272 patients (65.1%) achieved remission and 146 patients (34.9%) achieved un-remission when assessed STE of 418 patients. Patients in the high TVCR group (≥ 6.155%) and low TVCR group (< 6.155%) were significant with GTVp (P < 0.001). In univariate analysis, age, cT-stage, TNM stage, treatment modality, primary GTV and TVCR were associated with STE (P = 0.029, 0.027, 0.009, 0.035, < 0.001, < 0.001). Among the factors affecting the STE in multivariate analysis, gender and TVCR were statistically significant (P = 0.010, < 0.001). Meanwhile, the prediction model formed by gender and TVCR has a good prediction effect, with the area under the receiver operating characteristic curve was 0.876 (P < 0.001). There was a positive correlation between primary GTV as well as reposition dose, and TVCR (r = 0.413, 0.221), whereas the curative effects primary GTV exceeded that of reposition dose. TVCR could serve to forecast STE of radiotherapy in ESCC. It was of great significance to guide the individualized treatment of ESCC.