Analysis of relationship between CT-GTV and prognosis in patients with esophageal cancer after three-dimensional radiotherapy

Abstract

Objective To observe the relationship between computed tomography-gross tumor volume (GTV) and non-surgical T stage in patients with esophageal squamous cell carcinoma (ESCC) and the survival rates of patients with different GTVs,and to investigate the impact of GTV on the prognosis of ESCC after three-dimensional radiotherapy.Methods A retrospective analysis was performed on 223 ESCC patients without lymph node metastasis and distant metastasis who were hospitalized from July 2003 to January 2009.The prescribed doses of three-dimensional radiotherapy ranged from 50-70 Gy.These patients were divided into 3 or 4 groups according to different percentile intervals of GTVs.The Spearman rank correlation analysis was used for investigating the relationship between non-surgical T stage and GTV.The Kaplan-Meier method was used for calculating survival rates,and the log-rank test was used for survival difference analysis.Results The follow-up rate was 98.2％.A total of 163 patients were followed up for at least 3 years.The median GTVs of patients with T1 +2 ESCC,T3 ESCC,and T4 ESCC were 19.31 cm3,33.69 cm3,and 41.25 cm3,respectively,exhibiting a positive correlation between non-surgical T stage and GTV (P =0.000).The 5-year survival rates were 59％,43％,and 24％ (P =0.000) in 3 GTV-based groups and were 55％,51％,31％,and 24％ (P =0.004) in 4 GTV-based groups.The primary cause of death for the patients with GTVs of ≤35 cm3 and ＞35 cm3 was failure of local control (57.9％ vs 52.1％) ; 21.9％ and 13.8％ of the patients with a GTV of ＞ 35 cm3 died of uncontrol and excessive bleeding,versus 9.4％ and 3.1％ of the patients with a GTV of ≤ 35 cm3 (P =0.046 ; P =0.029) ;2 of the patients with a GTV of ＞ 35 cm3 died of grade 5 radiation pneumonitis.Conclusions GTV is positively correlated with nonsurgical T stage in esophageal cancer patients who receive radiotherapy.The 3-level and 4-level grading of GTV can be used for prognostic evaluation,and the 3-level grading of GTV is more closely related to prognosis.The patients with a larger GTV have higher incidence of uncontrol and bleeding and risk of treatment-related death than those with a smaller GTV after radiotherapy. Key words: Esophageal neoplasms/three dimensional radiotherapy; Gross tumor volume; Prognosis