T1 Gastric Cancer Is Associated With a High Incidence of Regional Lymph Node Metastases.

INTRODUCTION

Early stage gastric cancer, particularly T1 disease, is associated with high recurrence-free and overall survival rates following resection with curative intent. However, rare cases of T1 gastric cancer have nodal metastasis and this is associated with poor outcomes.

METHODS

Data from gastric cancer patients treated with surgical resection and D2 lymph node (LN) dissection at a single tertiary care institution from 2010 to 2020 were analyzed. Patients with early stage (T1) tumors were assessed in detail to identify variables associated with regional LN metastasis including histologic differentiation, signet ring cells, demographics, smoking history, neoadjuvant therapy, and clinical staging by endoscopic ultrasound (EUS). We used standard statistical techniques including Mann-Whitney U and Chi-squared tests.

RESULTS

Of 426 patients undergoing surgery for gastric cancer, 34% (n = 146) were diagnosed with T1 disease on surgical pathology. Among 146 T1 (T1a, T1b) gastric cancers, 24 patients [(17%) T1a (n = 4), T1b (n = 20)] had histologically confirmed regional LN metastases. The age at diagnosis ranged between 19 and 91 y and 54.8% were male. Prior smoking status was not associated with nodal positivity (P = 0.650). Of the 24 patients with positive LN on final pathology, seven patients received neoadjuvant chemotherapy. EUS was performed on 98 (67%) of the 146 T1 patients. Of these patients, 12 (13.2%) had positive LN on final pathology; however, none (0/12) were detected on preoperative EUS. There was no association between node status on EUS and node status on final pathology (P = 0.113). The sensitivity of EUS for N status was 0%, specificity was 84.4%, negative predictive value was 82.2% and positive predictive value was 0%. Signet ring cells were identified in 42% of node negative T1 tumors and 64% of node positive T1 tumors (P = 0.063). For LN positive cases on surgical pathology, 37.5% had poor differentiation, 42% had lymphovascular invasion, and regional nodal metastases were associated with increasing T stage (P = 0.003).

CONCLUSIONS

T1 gastric cancer is associated with a substantial risk (17%) of regional LN metastasis, when pathologically staged following surgical resection and D2 lymphadenectomy. Clinically staged N+ disease by EUS was not significantly associated with pathologically staged N+ disease in these patients.