Is the new seventh AJCC/UICC staging system appropriate for patients with gastric cancer?
BACKGROUND
The purpose of this study was to compare the clinical usefulness of the seventh Union Internationale Contre le Cancer/American Joint Committee on Cancer (AJCC/UICC) staging system vs the sixth AJCC/UICC staging system in patients with gastric cancer.


METHODS
Included were 1,799 patients who underwent surgery for gastric cancer between January 2001 and June 2005 at the National Cancer Center (South Korea). For the sixth and seventh AJCC/UICC staging systems, survival outcomes stratified by stage, by T classification, and by N classification were summarized using Kaplan-Meier curves and compared statistically using a log rank test; survival differences were quantified using hazard ratios estimated from a Cox regression model. The 2 systems were compared in terms of prognostic performances using the linear trend chi-square test, likelihood ratio chi-square test, and Akaike information criterion (AIC) in the Cox regression analysis.


RESULTS
Significant survival differences between each stage were not found using the seventh staging system, especially for stages IB, IIA, and IIB (p = 0.14 and p = 0.11). The sixth staging system had higher linear trend chi-square score and likelihood ratio chi-square score, which means better discriminatory ability, monotonicity, and homogeneity, and had smaller AIC, which indicates better optimistic prognostic stratification, especially in the N classification. The modified staging system combining the T classification of the seventh AJCC/UICC system and the N classification of the sixth system showed better prognostic performance compared with each separate version (sixth or seventh) of the staging system.


CONCLUSIONS
The seventh AJCC/UICC staging system is not more clinically useful than the sixth system in surgically treated patients with gastric cancer because of an inappropriate N classification. A new TNM system is required with a different N classification.
Gastric Cancer Branch, Research Institute and Hospital, Gyeonggi-do, Korea.
Hong Man
HM
Yoon
Keun Won
KW
Ryu
Byung Ho
BH
Nam
Soo Jeong
SJ
Cho
Sook Ryun
SR
Park
Jong Yeul
JY
Lee
Jun Ho
JH
Lee
Myeong-Cherl
MC
Kook
Il Ju
IJ
Choi
Young-Woo
YW
Kim
D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D011379:Prognosis; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000145:classification* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D015996:Survival Rate