Pathological Relative Risk And Dosimetry Analysis For Postoperative Radiation In Gastric Cancer After Radical Gastrectomy

Part I Pathological relative risk analysis for postoperative radiation in gastric cancer after radical gastrectomyMdthod : From Feb 2004 to Jan 2006, a total of 110 patients with newly diagnosed stomach carcinoma were enrolled in the study. All patients underwent gastrectomy with D1/D2 lymph node dissection and had complete postoperative pathologic analysis. Pathologically, all one were confirmed with R0 disease.Univariate analysis was applied on the pathlogic information and multivariate analysis was applied based on the univariate analysis.Result :(1)Univariate analysis revealed that tumor diameter,histology,vascular invasion,lymphatic vessel invasion and neural invasion were correlated with T/N classification.Multivariate analysis revealed that vascular invasion and lymphatic vessel invasion were associated with T classification and lymphatic vessel invasion was associated with N classification. (2) For T and N classifications, lymphatic vessel invasion was strongly relevant factor. Lymphatic vessel invasion had strong correlation with vascular invasion and neural invasion,but had poor consistency. (3)In LVI-positive patients, the proportion of T3,4 was 87.5%,and the proportion of N classification was 75%.Conclusion: For T and N classifications, lymphatic vessel invasion was strongly relevant factor. For patients with pathologically confirmed lymphatic vessel invasion, postoperative adjuvant radiotherapy is recommended. Part II Dosimetry studies of different radiation technique for gastric cancerObjective: To compare the dose distribution and dose-volume histograms (DVHs)of three-dimensional conformal radiotherapy(3D-CRT),7 fields radiotherapy (7F- RT) and intensity modulated radiation therapy(IMRT) of the planning target volume(PTV)and critical organs in gastric cancer treatment planning.Methods: From Aug 2007 to Dec 2008,5 patients with pathologically confirmed stage T3,T4 or N+ gastric carcinoma were enrolled in the study. All patients underwent radical gastrectomy. A dosimetry study was carried out on these five patients. For each patient, three kinds of treatment planning were designed with a prescribed dose of 45Gy to 95 % of PTV.The following parameters of these plans in each patient were compared:isodose distributions line,dose-volume histogram(DVH),V95%,V110%,CI,HI,EI of target volume and the dose of related critical organs.Results:IMRT showed better dose uniformity than 3D-CRT and 7F-RT(P<0.05),there was no statistical difference between 3D-CRT and 7F-RT in CI(P>0.05).IMRT showed better dose conformity than 3D-CRT and 7F-RT(P<0.05), and 3D-CRT was superior to 7F-RT in CI(P<0.05).IMRT showed better EI than 3D-CRT and 7F-RT(P<0.05),there was no statistical difference between 3D-CRT and 7F-RT in EI(P>0.05).IMRT had advantage at sparing liver compared with 3DCRT and 7F-RT(P<0.05),7F-RT showed better D1/3 of liver than 3D-CRT(P<0.05),but there was no statistical difference between 3D-CRT and 7F-RT in Dmean of liver(P>0.05).IMRT showed better Dmax of spinal cord than 3D-CRT and 7F-RT(P<0.05), and 7F-RT was superior to IMRT in Dmax of spinal cord(P<0.05).But the dose received by the both kidneys were not significantly different.Conclusion:Plans of IMRT were superior to 3D-CRT and 7F-RT,and 3D-CRT plans were superior to 7F-RT in CI and Dmax of spinal cord,then 7F-RT showed better D1/3 of liver than 3D-CRT.IMRT would appear to be the favored technique for gastric cancer radiation with regard to nodal treatment. IMRT was hoped to give some help to clinic.