Clinical And Molecular Prognostic Factors In Gastric Cancer

Objectives:Clinicopathologic characteristics,treatment and outcome were analyzed to construct prognostic model based on prognostic factors in the retrospective study of patients with operable gastric cancer.Expressions of molecular markers related tumor progression were detected and prognostic significances of those of them were analyzed as well.Transcription and protein expression of these genes were detected and analyzed in gastric cancer cell lines.Materials and Methods:Clinical data of 1043 patients with primary gastric cancer, who were treated with combined modality therapy based on surgery between 1999 and 2002 at Cancer Hospital,Chinese Academy of Medical Sciences,were accrued. Clinicopathologic characteristics,therapeutic methods and outcome were analyzed. Clinical data of 1284 gastric cancer patients,who received the combined modality treatment based on surgery between 1999 and 2006 at Cancer Hospital,Chinese Academy of Medical Sciences,were randomized into training sample(n=963) and validation sample(n=321).Prognostic model defined by prognostic index was established in training sample and was detected in validation sample and all patients(n=1284).All paraffin-embedded tissue sections were obtained from 89 gastric cancer patients who underwent curative gastrectomy between 1999 and 2000 at Cancer Hospital,Chinese Academy of Medical Sciences.Clinical data of 89 patients were collected as well.No neoadjuvant and/or adjuvant therapy was applied to the 89 patients.Expression of Aurora-A,VEGF-A,VEGF-D/VEGFR-2,VEGFR-3 were detected in sections using immunohistochemistry technology.Correlation between protein expression and clinicopathologic characteristics as well as prognosis was analyzed.Survival information of all patients was acquired by telephone communication and/or correspondence.Statistical calculations were performed using Statistical Package for the Social Science software(version 13.0;SPSS Inc.,Chicago, IL).Comparison of the qualitative data was done by Chi-square analysis. Nonparametric Tests of Independent samples were performed using Mann-Whitney U test or Kruskal-Wallis H test.Relationship between protein expression and clinicopathologic characteristics was evaluated using Spearman rank correlation coefficient.Relationship between clinicopathologic characteristics and prognosis was analyzed by Logistic regression analysis.Median survival time and overall survival was estimated by Life Table or Kaplan-Meier methods.The difference between survival curves was performed using Log-rank test.Factors with prognostic significance in univariate analysis were included in multivariate survival analyses using Cox proportional hazard model.P value was two-side,less than 0.05 as statistical significance.The mRNA and protein of Aurora-A,VEGF-A and VEGF-D was respectively detected with Real time RT-PCR and Western blot in eight kind of gastric cancer cell lines including AGS,MGC803,MKN45,BGC823,SUN-5,N87, SNU-16 and SGC7901.Results:Proximal tumor was predominantly observed in primary tumor site, accounting for 46.8%,in 1043 gastric cancer patients treated with combined modality therapy based on surgery.Proximal gastric cancer,accounting for 51.9%,was prevalent in male patients and distal gastric cancer,accounting for 39.7%,was more common in female patients.Adenocarcinoma was predominant pathologic type, accounting for 77.9%.StageⅢ/Ⅳwas commonly seen,accounting for 69.1%.The MST and RFS were 39.5 months and 22.7 months,respectively.The 5-year overall survival(OS) and the 5-year relapse-free survival(RFS) were 39%and 15%, respectively.The 5-year OS according to stage 0,ⅠA,ⅠB,Ⅱ,ⅢA,ⅢB andⅣwere 100%,91%,84%,61%,33%,19%and 5%,respectively.Age at diagnosis(≤60 years vs.＞60 years),primary tumor site(proximal vs.non-proximal),tumor size(≤10cm vs.＞10cm),stage,ratio of lymphonode metastasis(LNM)(≤1/3 vs.＞1/3),peritoneal cavity involvement(PCI)(present vs.absent),curative gastrectomy(present vs. absent)and combhled modality therapy(present vs.absent)were the independent prognostic factors affecting overall survival in Cox proportional hazard model. Primary tumor site and stage were the independent prognostic factors affecting relapse-free survival.Age at diagnosis,primary tumor site,stage,ratio of LNM,PCI, curative gastrectomy and combined modality therapy were the independent prognostic factors affecting overall survival in training sample by Logistic regression analysis. After weighting relative risk of death of the 5 non-therapeutic prognostic factors, equation for predicting relative risk of death was established.Prognostic quation=Age + site +(stage + ratio of LNM + PCI)×2.If patient had an unfavorable prognostic factor,the score was recorded as 1.Otherwise,the score was record as 1.Prognostic index was acquired from score 0 to 8 according to the prognostic factors included in equation.Four risk groups defined by prognostic index were low risk(L,score 0-1), low intermediate risk(LI,score 2-3),high intermediate risk(HI,score 4-5) and high risk(H,score 6-8),respectively.Risk groups established by training sample were tested to be well consistent in validation sample and all patients.The 5-year overall survival of L,LI,HI and H in all patients were 81%,53%,22%and 4%,respectively. Risk groups could identify patients of different relative risk of death in the same stage from stageⅠB toⅣ.Aurora-A,stage and lympovascular involvement were independent prognostic factors affecting overall survival in 89 gastric cancer patients who were treated with curative gastrectomy(R0 resection) and had no adjuvant therapy(P value were 0.001,＜0.001 and 0.007,respectively).Aurora-A and VEGF-D were expressed in gastric cancer cell lines from different differentiated types in protein level.VEGF-A was highly expressed in gastric cancer cell lines of poorly differentiated type in protein level.Aurora-A highly expressed in mRNA level was observed in gastric cancer cell lines of well and moderately differentiated status. VEGF-A highly expressed in mRNA level was in gastric cancer cell lines of poorly differentiated status.VEGF-D highly expressed in mRNA level was in gastric cancer cell lines of moderately and poorly differentiated status.Conclusion:Age at diagnosis,primary tumor site,tumor size,stage,ratio of lymphonode metastasis,peritoneal cavity involvement,curative gastrectomy and combined modality treatment were independent prognostic factors in gastric cancer. Prognostic model constructed by prognostic index was well consistent in clinical outcome,and importantly,it could identify different relative risks of death in the same stage from stageⅠB toⅣ.Aurora-A was a novel,independent,molecular prognostic factor in gastric cancer.Aurora-A,VEGF-A and VEGF-D were characterized respectively in expression of mRNA and protein in gastric cancer cell lines from different differentiated types.