[Comparison of the superiority of different TNM staging systems in Siewert III adenocarcinoma of esophagogastric junction].

OBJECTIVE: To compare the prognostic value of TNM staging systems in the 7th edition and the 8th edition AJCC in Siewert III adenocarcinoma of esophagogastric junction (AEG).

METHODS: Data of 160 patients with Siewert III AEG who underwent radical surgery (R0) from January 2009 to January 2013 in PLA General Hospital were collected retrospectively. Exclusion standards:(1)preoperative neoadjuvant chemoradiotherapy;(2)with distant metastasis before or during operation;(3)palliative operation or R1/R2 resection;(4)pathological type as non-adenocarcinoma;(5)number of retrieved lymph nodes less than 16;(6)diagnosed with other malignant tumors concurrently or within 5 years after operation;(7)incomplete clinical or follow-up data. According to the above criteria, 160 patients were included in this study finally. All the patients underwent radical total or proximal gastrectomy by abdominal approach. D1 or D1+ lymph node dissection was performed in early patients and D2 in advanced patients. All the patients were re-staged by the gastric cancer TNM7 (G7), the gastric cancer TNM8 (G8) and the esophageal cancer TNM7(E7). Univariate analysis and Cox regression analysis were performed. Kappa value and Akaike's information criterion (AIC, the less AIC, the better prognosis) value were compared between different staging systems in agreement and predicting prognosis.

RESULTS: There were 128 males and 32 females(sex ratio 4:1), and the average age was (60.2±11.6) years and 17 patients with basic disease. Of all the patients, 133 cases (83.1%) underwent radical total gastrectomy and 27 cases (16.9%) underwent proximal gastrectomy. The median number of dissected lymph nodes were 31 and the median number of positive lymph nodes were 4. Multivariate analysis showed that the G7, G8, E7 staging systems were independent prognostic factors (HR=1.374, 1.407 and 1.305 respectively,all P<0.001). Stage migration between G7 and G8 were only observed in IIIA, IIIB and IIIC, and stage migration rate was 8.1% (13/160), and the agreement was very good (weighted Kappa 0.904, P<0.001). However, the difference between G8 and E7 was quite obvious, stage migration rate was 40.6%(65/160), and the agreement between G8 and E7 was not satisfied (weighted Kappa 0.536, P<0.001). AIC value was 811.4 in G8, 812.8 in G7 and 815.9 in E7, respectively.

CONCLUSION: Compared with G7 and E7 staging systems, the G8 staging system is superior in predicting the prognosis of patients with Siewert III AEG.