The Clinical Value Of Contouring Clinical Target Volume For Radiotherapy In Locally Advanced Non-small Cell Lung Cancer

Objective: To evaluate the clinical value of contouring clinical target volume for radiotherapy in locally advanced non-small cell lung cancer.Methods: In this study, 177 patients with locally advanced NSCLC diagnosed by pathology or cytology whose KPS scores were above 70 marks were in Fujian Provincial Tumor Hospital from January 2006 to January 2012. All patients completed the radiotherapy. Their clinical stages were IIB-IV periods. All patients received 2~4 periods of induction chemotherapy with platinum. All patients were divided into two groups of group A and group B. Group A is the group of contouring GTV and PTV, without CTV, including 135 cases(115 male and 20 females; aged 41 to 76 years, average 60.3±8.8 years of age),including 67 cases of squamous cell carcinomas, 51 cases of adenocarcinoma and 17 cases others,and including 5 cases of stage IIB, 51 cases of stage IIIA, 65 cases of stage IIIB and 14 cases of stage IV respectively.Group B is the group of contouring GTV, CTV and PTV, including 42 cases(37 male and 5 females; aged 38 to 77 years, average 59.9±10.0 years of age),including 22 cases of squamous cell carcinomas, 11 cases of adenocarcinoma and 9 cases others,and including 4 cases of stage IIB, 11 cases of stage IIIA, 24 cases of stage IIIB and 3 cases of stage IV respectively. There was no statistically significant difference in two groups of clinical datas.The CT scan was carried out in all patients. The scan data were transferred to Pinnacle 8.0m Planning System. Two attending physicians delineated GTV(gross tumor volume), PTV(planning target volume),CTV(clinical target volume), and OAR(organs at risk). OARs include lung, esophagus, spinal cord, trachea and heart et.al.They all adopted IMRT(Intensity Modulated Radiation Therapy) as treatment plans. Lung tumor received total dose from 60 Gy to 66 Gy. Regions of clinical target volume received 46~52Gy. In consideration of adequate covering of GTV, PTV received >95% of the treatment dose. Constrains were placed on the dose to the spinal cord(45Gy), heart(V40<40%), trachea(60Gy),esophagus(V60<50%), lung(V20<25%~30% and MLD<15Gy). Statistical software used SPSS17.0.Results: The mean dose of lung in without CTV group is 61.77Gy±2.87 Gy, in with CTV group is 61.97Gy±2.74Gy(P=0.638). The overall response rate(CR+PR) in without CTV group and in with CTV group was 76.30% and 83.33%(P=0.230). The 1-year, 2-year and 3-year local control rates in without CTV group were 52.98%, 35.35% and 24.3%; and the 1-year, 2-year and 3-year local control rates in with CTV group were 38.95%, 24.33% and 11.5%(P=0.360). Local recurrences parts are within the GTV. The 1-year, 2-year and 3-year overall survival rates in without CTV group were 69.90%, 45.30% and 30.80%; and the 1-year, 2-year and 3-year overall survival rates in with CTV group were 62.18%, 37.59%, and 26.58%(P=0.573). The 1-year, 2-year and 3-year free from distant metastasis survival rates in without CTV group were 61.07%, 40.27% and 30.4%; and the 1-year, 2-year and 3-year free from distant metastasis survival rates in with CTV group were 43.55%, 32.03% and 27.56%(P=0.481). The incidence of pulmonary toxicity, esophageal toxicity and myelosuppression in without CTV group and in with CTV group were 16.30% and 33.33%(P=0.017);18.52% and 21.43%(P=0.414);38.52% and 33.33%(P=0.338), respectively. None of the 177 patients developed grade-3 or worse pulmonary toxicity and grade-2 or worse esophageal toxicity.Conclusion: Radiation therapy without contouring CTV in locally advanced non-small cell lung cancer did not increase local recurrence and decreased survival rates, but reduced the incidence of radiation pneumonia. It can improve the quality of survival. And local recurrences parts are within the GTV. So this treatment of without contouring CTV is feasible.