title: Incorporation of extranodal metastasis of gastric carcinoma into the 7th edition UICC TNM staging system.
abstract: BACKGROUND
  To assess the clinical significance and prognostic impact of extranodal metastasis (EM) in gastric carcinoma and establish an optimal classification in the staging system.
  
  
  RESULTS
  A total of 1343 patients with gastric carcinoma who underwent surgical resection were recruited to determine the frequency and prognostic significance of EMs. EMs were divided into two groups (EM1 and EM2) and then incorporated into the 7(th) edition UICC TNM staging system. EMs was detected in 179 (13.3%) of 1343 patients who underwent radical resection. Multivariate analysis identified EMs as an independent prognostic factor (HR = 1.412, 95%CI = 1.151-1.731, P<0.001). After curative operation, the overall survival rate were worse in patients with ≥3 cases of EM (EM2) than those with the number of 1 and 2 cases (EM1) (P<0.001). Survival of patients with EM1 was found almost comparable to that of N3 stage (P = 0.437). Survival of patients with EM2 showed similar to that of stage IV patients (P = 0.896). By using the linear trend X(2), likelihood ratio X(2), and Akaike information criterion (AIC) test, EM1 treated as N3 stage and EM2 treated as M1 stage performed higher linear trend X(2) scores, likelihood ratio X(2) scores, and lower AIC value than the 7(th) edition UICC TNM staging system, which represented the optimum prognostic stratification, together with better homogeneity, discriminatory ability, and monotonicity of gradients.
  
  
  CONCLUSIONS
  EMs might be classified based on their number and prognostic information and should incorporate into the TNM staging system.
authors.affiliation: State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Yuanfang
authors.initials: Y
authors.lastname: Li
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiuhong
authors.initials: X
authors.lastname: Yuan
authors.forename: Dazhi
authors.initials: D
authors.lastname: Xu
authors.forename: Yuanxiang
authors.initials: Y
authors.lastname: Guan
authors.forename: Xingyu
authors.initials: X
authors.lastname: Feng
authors.forename: Yingbo
authors.initials: Y
authors.lastname: Chen
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Sun
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Youqing
authors.initials: Y
authors.lastname: Zhan
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011379:Prognosis; D013274:Stomach Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D016019:Survival Analysis; D055815:Young Adult