Effects of gross tumor volume and positive lymph node volume on prognosis of intensity-modulated radiotherapy for esophageal squamous cell carcinoma

Objective: To analyze the effects of gross tumor volume (GTV-T) and positive lymph node volume (GTV-LN) on the prognosis of radical concurrent chemoradiotherapy for esophageal squamous cell carcinoma (ESCC). Methods: A total of 79 patients with stage N₁ ESCC undergoing radical radiotherapy in our hospital from 2012 to 2015 were enrolled as subjects. GTV-T and GTV-LN were calculated by the Pinnacle³ 9.0 treatment planning system. The receiver operating characteristic (ROC) curves wee used to evaluate the value of the GTV-LN/GTV-T ratio in the prediction of local recurrence (LR) and distant metastasis (DM) of ESCC. Results: The median follow-up time was 17.2 months in all patients. The ROC curves were made using the GTV-LN/GTV-T ratio. The optimal cut-off values of GTV-LN/GTV-T ratio for predicting the risk of LR and DM were 0.34 and 0.59, respectively. The statistical analysis revealed that the LR rates were 50% and 8% in patients with GTV-LN/GTV-T ratios of< 0.34 and ≥ 0.34, respectively (P < 0.01), while the DM rates were 11% and 43% in patients with GTV-LN/GTV-T ratios of < 0.59 and ≥ 0.59, respectively (P = 0.003). Conclusions: The GTV-LN/GTV-T ratio may be a predictor of LR and DM in patients with ESCC. Further studies on the GTV-LN/GTV-T ratio may help to make personalized chemoradiotherapy strategies for patients with ESCC. (authors)