Prognostic significance of isolated tumor cells in regional lymph nodes in patients with T2-T3 stage gastric cancer.

Abstract

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.