Gross tumor volume is the prognostic factor for squamous cell esophageal cancer patients treated with definitive radiotherapy

Background: To investigate whether gross tumor volume (GTV) defined on radiotherapy planning scans a prognostic factor for esophageal squamous cell carcinoma (ESCC) patients treated with definitive radiotherapy. Methods: From 2008 to 2011, 187 ESCC patients who were treated with definitive radio(chemo) therapy were analyzed retrospectively. Tumor volumes such as GTV, gross tumor volume of primary esophageal cancer (GTV-P), and gross tumor volume of metastases lymph nodes (GTV-N) were computed by Philips Healthcare radiation therapy planning system (Pinnacle 8.0). Kaplan-Meier cumulative probability and Cox proportional hazards regression models were used to assess the effect of the clinical factors along with tumor volume on progression-free survival (PFS) and overall survival (OS). Results: In the univariate analysis, fraction dose, TNM stage, total radiation dose, GTV, GTV-P, and GTV-N were all significantly associated with both OS and PFS (P<0.05). While in multivariate analysis, GTV and fraction dose were significantly associated with both OS and PFS (adjusted P<0.05) with adjustment for age, sex, smoking status, chemotherapy, fraction dose, GTV, and radiation dose. Conclusions: GTV may serve as a good prognostic factor for ESCC patients treated with definitive radiotherapy. Larger prospective studies are needed to validate these findings.