The 8th edition American Joint Committee on gastric cancer pathological staging classification performs well in a population with high proportion of locally advanced disease 基隆長庚醫院 一般外科 簡禔萱 Shu-Fang Huang, BS, Ti-Hsuan Chien, MD, Wen-Liang Fang, MD, Frank Wang, MBBS MClinEpid FRACS, Chun-Yi Tsai, MD, Jun-Te Hsu, MD,Chun-Nan Yeh, MD, Tse-Ching Chen, MD, PhD, Ren-Chin Wu, MD, PhD, Cheng-Tang Chiu, MD, and Ta-Sen Yeh, MD, PhD Departments of Surgery, Pathology, and Gastroenterology, Chang Gung Memorial Hospital at Linkou Chang Gung University, College of Medicine, Taoyuan, Taiwan Division of General Surgery, Taipei Veterans General Hospital, Taiwan School of Medicine, Western Sydney University, Campbelltown, NSW, Australia

Background • IGCA database[25411]: Japanese[10633], Korean[10922], other Asia[1627], Western[2229] • T/N status: T[1/2/3/4a/4b], N[0/1/2/3a/3b] • 7/25 T/N groups in the AJCC 8 different in AJCC 7 • T4aN2M0(IIIB->IIIA) T4bN0M0(IIIB->IIIA) T1N3bM0(IIB->IIIB) T2N3bM0(IIIA->IIIB) T4aN3aM0(IIIC->IIIB) T4bN2M0(IIIC->IIIB) T3N3bM0(IIIB->IIIC)

Motivation to Validate The concerns • Predominately based on Japanese and Korean patients(85%) • 52% cohort were stage I Aim • Validate the 8th AJCC in locally advanced gastric cancer and older age • Evaluate the lymph node ratio (LNR) in N3b disease

Patients and methods • Retrospective study • 5386 patients with gastric cancer underwent curative gastrectomy • 1994-2011, Chang Gung Memorial Hospital at Linkou(CGMH, n=3301) and Veteran General Hospital in Taipei(TVGH, n=1939), Taiwan • Exclusion: Hospital mortality(n=146, 2.7%)  Total 5240 patients • M1 disease confirmed at laparotomy(n=566)control in the survival analysis • Pathological stages were determined by the AJCC7 and AJCC8 • From the date of surgery to the date of the last follow up or December 31, 2012

Statistical analysis Numerical data were expressed as mean ± SD or median. Fischer’s exact test or Pearson’s χ 2 test were used to compare categorical data. Kaplan-Meir method was used to assess survival outcomes, and differences were analyzed by the log-rank test. The optimal cutoff values for LNR were determined according to the survival tree using R software, Version 3.1.3 Akaike Information Criterion (AIC) indicated the performance of prognostic stratification. The likelihood ratio χ2 test was used to measure homogeneity. The linear trend χ2 test was used to measure the discriminatory powers and monotonicity, and the AIC was employed to assess model fit. Potential prognostic factors obtained from the univariate analysis were assessed in the multivariate model using Cox’s regression. A p value <0.05 was considered statistically significant. Statistical analyses were performed using SPSS for Windows, version 13 (SPSS, Inc., Chicago, IL, USA).

Results

Conclusion The 8th AJCC pathological staging classification is better than the 7th AJCC

N3b-LNR(lymph node ratio) Many studies have been reported that lymph node metastasis(nodal status) is considered to be the strongest independent prognostic factor

3 subgroups: LNR <0.35(65), 0.35-0.79(43) and >0.79(35)

Conclusion 1 2 Our data confirms the AJCC8 performs well by more locally advanced disease and elderly patients 1 2 We recommend that LNR is a useful supplementary prognostic indicator for gastric cancer with N3b disease

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