The Expression Of RASSF6 In Advanced Lung Adenocarcinoma And Its Clinical Significance

ObjectiveTo evaluate the expression of RASSF6 in advanced lung adenocarcinoma and its association with clinicopathological features and prognosis.Methods1.Subjects and specimens collectionFrom January 1,2012 to December 31,2014,cancer tissues from 100 advanced lung adenocarcinoma patients with complete clinical and pathologic data were used as the case group,and the adjacent normal lung tissues from other 100 lung cancer patients were selected as the control group.The tissue samples were processed by paraffin embedding technology.2.RASSF6 expression detectionThe expression of RASSF6 in lung adenocarcinoma and adjacent normal lung tissues was detected by immunohistochemistry.3.Statistical analysisAll statistical analyses were performed using SPSS19.0 software.The expression of RASSF6 in lung adenocarcinoma and adjacent normal lung tissues was compared by chi-square test.The correlation between RASSF6 expression and clinicopathological features of lung adenocarcinoma were accessed with chi-square test.Kaplan-Meier method and log-rank test were used to compare the survival of RASF6 positive expression group and RASSF6 negative expression group.Multivariate Cox regression models were used to evaluate the association between gender,age,smoking,brain metastasis,EGFR,RASSF6 and prognosis of lung cancer.Results1.Immunohistochemistry results demostrated that RASSF6 in lung adenocarcinoma cells showed positive staining of cytoplasm(positive rate was 44%).While the adjacent normal lung tissue cells showed positive staining of cytoplasm and nucleus(positive rate was 59%).The distribution of age,gender,smoking status were similar between experimental group and control group(all P>0.05).The positive rate of RASSF6 expression in lung adenocarcinoma tissue was significantly lower than that in adjacent normal tissues(P = 0.034).2.The expression of RASSF6 was correlated with tumor differentiation(P =0.001),brain metastasis(P =0.006),TNM stage(P=0.010)and EGFR mutation(P =0.010),and EGFR mutation types(P =0.016).But no correlation were observed with gender(P =0.435),age(P =0.414),and smoking(P =0.598).3.Survival analysis showed that the median PFS of RASSF6 expression positive group and RASSF6 expression negative group were 14 months and 7 months,respectively,and the difference was statistically significant(?~2 = 25.489,P <0.001).The median OS of the two groups were 26 months and 12 months,the difference was statistically significant(?~2=27.364,P<0.001).4.EGFR mutation(P=0.006)and RASSF6 expression(P<0.001)were associated with the prognosis of advanced lung adenocarcinoma.But the same correlations were not found with gender(P=0.806),age(P=0.801),stage(P=0.827),brain metastasis(P=0.842)and smoking(P=0.407).Conclusions1.RASSF6 appears down-regulated in stage ? lung adenocarcinoma.2.There was a correlation between the expression of RASSF6 and the differentiation of advanced lung adenocarcinoma,brain metastasis,TNM stage,EGFR mutations and EGFR mutation types.3.Downregulation of RASSF6 expression suggests a poor prognosis in advanced lung adenocarcinoma.4.RASSF6 may be an independent prognostic factor for advanced lung adenocarcinoma.