The Relationship Between Radiation Dose At Different Distances Of Tumor Margins And Prognosis In N0 Stage Thoracic Esophageal Squamous Cell Carcinoma

Objective: To accurately define does bound of esophageal carcinoma for radiotherapy, this study investigates therelationship between radiation dose at different distances of tumor margins and prognosis in stage N0 esophageal carcinoma.Methods: From Jan.2004 to Dec.2008, 72 cases newly diagnosed N0 stage thoracic esophageal squamous cell carcinomas were included in this retrospective study. All tureatment plans were set up and designed by CT simulator and 3D TPS. They received dose 56~70Gy/27~33F/6~7w with 6MV-X ray. Esophageal carcinoma stageI 6 cases,IIa 33cases,III 33cases. We collected the edge dose of primary tumor at different distances (0.5(0.9)cm,1(2.1)cm,1.5(3.0)cm, 2(3.9) cm) and at different direction.Kapian-Meier and Log-rank was used for statistical analysis.Results: (1)The survival rates in the group GTV accepted over 60 Gy were higher than those accepted less than 60 Gy, but had no significant difference (χ2=0.534,P=0.465).(2) The hightest survival rates was showed by does between 63 and 67Gy at the left side off tumor 0.5cm,63~67Gy group and <63Gy group have significant difference (χ2=5.982,P=0.014);The edge dose of left side off tumor 1.0cm, 1,2,3-year survival rates in group accepted over 62 Gy were higher than those accepted less than 62Gy, and had significant difference (χ2=4.585,P=0.032). The edge dose of left side off tumor 1.5cm, the 1,2,3-year survival rates in any group had no significant difference. The edge dose of left side off tumor 2.0cm, the survival rates in the group accepted over 41 Gy were higher than those accepted no more than 41 Gy, had significant difference (χ2=4.728,P=0.030). (3) The edge dose of right side off tumor 0.5cm, reaching 60~64Gy,was at the hightest survival rates.The radiation dose of <60Gy group was at the lowest survival rates ; 60~64Gy group and <60Gy group had obviously significant difference (χ2=3.958,P=0.047); The edge dose of right side off tumor 1.0cm, 1,2,3-year survival rates in group accepted over 61Gy were higher than those accepted no more than 61 Gy, and had significant difference (χ2=4.568,P=0.033). The edge dose of right side off tumor 1.5cm, the overall survival rates in the group accepted over 56 Gy were higher than those accepted no more than 56 Gy, and had significant difference (χ2=3.971,P=0.046).The edge dose of right side off tumor 2.0cm, the overall survival rates in the group accepted over 44Gy were higher than those accepted no more than 44 Gy, and had significant difference (χ2=3.897,P=0.048).(4) The edge dose of anterior side off tumor 0.5cm, reaching 62~65Gy,was at the hightest survival rates. The radiation dose of <62Gy group was at the lowest survival rates ; 62~65Gy group and <62Gy group had obviously significant difference (χ2=4.525,P=0.033); The edge dose of anterior side off tumor 1.0cm, reaching 61~64Gy,was at the hightest survival rates. 61~64Gy group and <61Gy group had obviously significant difference (χ2=4.436,P=0.035); At 1.5cm off anterior side of tumor , reaching 62~66 Gy, was at the highest survival rates,having significant difference (χ2=6.108, P=0.047). The edge dose of anterior side off tumor 2.0cm, the 1,2,3-year survival rates in any group had no significant difference. (5) The hightest survival rates was showed by the does between 61 and 66 Gy at the posterior side off tumor 0.5cm. 61~66Gy group and <61Gy group have significant difference (χ2=4.40, P=0.036); At 1.0cm of posterior side off tumor ,reaching 60~64Gy ,was at the highest survival rates,having significant difference (χ2=4.422,P=0.035);The posterior side at the distance1.5 off tumor to accept different dose of irradiation, the survival rates were no significant difference (P>0.05). The edge dose of posterior side off tumor 2.0cm, the overall survival rates in the group accepted over 51Gy were higher than those accepted no more than 51 Gy, and had significant difference (χ2=4.599,P=0.032).(6) The superior side at the distance 0.9 and 3.9cm off tumor to accept different dose of irradiation, the 1,2,3-year survival rates were no significant difference (P>0.05). The superior side off tumor 2.1cm, reaching 56~62Gy ,was at the highest survival rates. 56~62 Gy group and <56Gy group have significant difference (χ2= 5.17,P=0.023); The superior side off tumor 3.0cm,, reaching 48~54Gy,was at the hightest survival rates.The radiation dose of >54Gy group was at the lowest survival rates. (7) The infererior side at the distance 0.9 and 2.1cm off tumor to accept different dose of irradiation, the survival rates were no significant difference (P>0.05). The infererior side off tumor 3.0cm, reaching 49~56Gy ,was at the highest survival rates. 49~56 Gy group and <49Gy group have significant difference (χ2= 4.696,P=0.030); The superior side off tumor 3.9cm,reaching 38~46Gy, was at the hightest survival rates.The radiation dose of <38Gy group was at the lowest survival rates. 38~46Gy group and <38Gy group had obviously significant difference (χ2=4.181,P=0.041).Conclusions: Appropriate target volume definition of N0 stage thoracic esophageal squamous cell carcinoma were:(1) The edge dose of surrongdings off tumor 0.5cm ,1.0cm and 2.0cm, need to accept 63~64Gy , 62~64Gy, >51Gy. (2) The superior side off tumor 2.1cm and 3.0cm need to accept 56~62Gy and 48~ 54Gy.(3) The infererior side off tumor 3.0cm and 3.9cm need to accept 49~56Gy and 38~46Gy.