8 Background: The prognostic impact of isolated tumor cells (ITCs) in regional lymph nodes is unclear. This study was aimed to evaluate the prognostic significance of ITCs in subpopulation with T2-T3 gastric cancer by adopting the standard definition for ITC (≤ 0.2 mm, detected by H&E or IHC) and micrometastsis (≤ 2 mm, detected by H&E or IHC) in 7th AJCC staging. Methods: A total of three hundred eleven patients diagnosed as pT2-3/N0-2/M0 gastric carcinoma after curative surgery at Korea Cancer Center Hospital between January 1996 and December 2000 was retrospectively studied. All tumor and lymph node specimens by H&E received reexaminations, and 5,825 lymph nodes from 191 patients without macrometastasis (> 2.0 mm) were re-evaluated after IHC staining with anti-cytokeratin (AE1/AE3). And N stage was reclassified into pN0(i-), pN0(i+), pN1mi, pN1, and pN2. Survival analyses were performed using Kaplan-Meier method with Log-rank test and Cox regression model. Results: According to original N stage, 5-year overall survival rates were estimated as 80.5% in N0, 79.3% in N1, 68.8% in N2 without statistical difference between N0 and N1 (p=0.790). Whereas according to reclassified pN stage, survival rates were estimated as 92.3% in pN0(i-), 75.5% in pN0(i+), 84.4% in pN1mi, 76.1% in pN1, and 69.0% in pN2, and significant difference was found between pN0(i-) and pN0(i+) (p=0.034). In the multivariate Cox model with backward conditional method, reclassified pN stage was remained as an independent prognostic factor along with age and tumor location while excluding original N stage, and the hazard ratio (95% CI) of pN0(i+) compared to pN0(i-) was 3.60 (1.08-12.00). Conclusions: The result demonstrates that ITCs in regional lymph nodes is a bad prognostic factor, even after adjusting for other prognostic factors. So we suggest that ITCs should be classified separately from the N0 in gastric cancer staging.
Prognostic implication of isolated tumor cells and micrometastases in regional lymph nodes of gastric cancer
