The Relationship Between Radiation Dose Of Tumor Margins And Prognosis In Stage â…¢ Central Non-small-cell Lung Cancer

Objective: To accurately define target volume of lung tumors for radiotherapy, this study investigates the relationship between radiation dose at different distances of tumor margins and prognosis in stage III central non-small-cell lung cancer.Methods: Between January 2004 and December 2007, 82 patients were treated with biopsy-proven stage III NSCLC who had undergone 3DCRT at the Hebei Medical University 4th hospital. NSCLC stage IIIA: 35%, IIIB: 65%. The total target dose was between 50 and 70Gy (median, 62Gy). We collected the edge doses of primary tumor at different distances(0.5cm, 1 cm, 1.5cm and 2cm) and at different directions. Kaplan-Meier and Log rank was used for statistical analysis.Results: (1)The median survival and 1-, 2- and 3-year overall survival (OS) in >60Gy group were higher than those in≤60Gy group, but there was no significant difference (P=0.168). (2)The median survival and overall survival in the patients whose primary tumors accepted >60Gy were higher than those who accepted≤60Gy, if primary volume of tumor were ≤100cm~3 (P=0.023). However, if >100cm~3, the two groups had no significant difference (P=0.821). (3)The highest OS was observed in the 60～66Gy group if the distance was 0.5cm from mediastinal side to tumor margin (P=0.022), and the 1cm margin, the 59～62Gy dose group was observed highest OS than other two groups (<59Gy and >62Gy). The lowest OS was found in <59Gy group, and there was significant difference in the two groups (59～62Gy group and <59Gy group) (P=0.040). After analysis to the 1.5cm margin from mediastinal side, the 3-year overall survival rate in the 50～60Gy group was 29.55%, and that in the >60Gy group was 17.63%, more than 5.95% in <50Gy group. There was significant difference between 50～60Gy and <50Gy grope. The survival rate date showed that there was higher OS in≥40Gy group than <40Gy group, at the margin 2cm from mediastinal side (P=0.029). (4)Our research showed that there was no significant difference in three groups (<60Gy, 60～66Gy, and >66Gy group) about 1-, 2- and 3-year survival rate at the distance 0.5cm from pneumonic side to tumor. About the distance 1cm, the OS in≥64Gy group was higher than that in <64Gy (P=0.030). The 3-year survival rate in≥60Gy group was 25.17% at the distance 1.5cm from pneumonic side to tumor margin, and it was higher than 14.72% in <60Gy group (P=0.020). Same result was observed in the distance 2cm, in the≧42Gy group the 3-year OS of patients was higher than that in <42Gy group (P=0.033). (5)At the analysis to the anterior side from tumor margin, there was no significant difference in all groups, about the OS. But higher OS was observed in the 60～64Gy group more than <60Gy group, if the distance was 1.5cm from anterior side to tumor margin (P=0.092). (6)There was no difference in those three groups (0.5cm, 1.5cm, 2cm distance from posterior side to tumor margin), about the OS. But the highest OS was found in >62Gy group, compared with other two groups (55～62Gy group and <55Gy group), and there was significant difference in the two groups (<55Gy group and >62Gy group) (P=0.049). (7)At the analysis to the superior side from tumor margin, there were no obviously difference in three all groups (P>0.05), about the OS. (8) Our research showed there were no significant differences in all groups (0.5cm, 1cm, 1.5cm)about the OS, to the inferior side from tumor margin. But higher OS was observed in >40Gy group more than the 20～40Gy group, if the distance was 2.0cm (P=0.045).Conclusion: (1) To central non-small cell lung cancer patients, the best dose line were >60Gy at the distance 1cm from mediastinal side from tumor margin, while >50Gy at the distance 1.5cm and not less than 40Gy at the distance 2cm from mediastinal side. In the pneumonic side, it was better that the dose was≥64Gy at the distance 1cm and≥42Gy at the distance 2cm. In anterior side, the dose 60～64Gy was suggested at the distance 1.5cm. It was better to >62Gy at the 1cm in posterior side, and at 2cm distance, the dose≥40Gy was suggested in inferior side. (2)The date showed us that the patients could achieve longer survival time if the tumor volume≤100m3 accepted >60Gy dose. (3)If the tumor volume was >100cm3, there was no benefit to survival rate by easily increasing the total dose.