Lymph node involvement in gastric adenocarcinoma

Endoscopic management of early gastric cancer is limited by the risk of lymph node metastasis. We aimed to examine the incidence and predictors of nodal metastasis in early gastric adenocarcinoma in a large national US cohort.

Cases were abstracted from the National Cancer Database from 2004 to 2016. The incidence and predictors of lymph node involvement for patients with Tis, T1a, and T1b tumors were examined.

A total of 202,216 cases of gastric adenocarcinoma were identified in the NCDB. Cases with unknown patient or tumor characteristics, presence of other cancers, and prior neoadjuvant chemotherapy or radiotherapy were excluded. 1839 cases of Tis, T1a, and T1b tumors were identified. Lymph node metastases were present in 18.1% of patients. Lymphovascular invasion (LVI), high-grade histology, stage T1b, and larger size (> 3 cm) were independently associated with an increased risk of nodal metastasis on multivariate analysis (P < 0.05). The presence of LVI was the strongest predictor of nodal metastasis with an OR (95% CI) of 5.7 (4.3-7.6), P < 0.001. No lymph node metastasis was found in any Tis tumors. Small T1a low-grade tumors with no LVI had a low risk of nodal metastasis (0.6% < 2 cm and 0.9% < 3 cm).

In this large national cohort, size, lymphovascular invasion, higher grade histology, and T stage were independently associated with lymph node metastasis. For patients with low-grade tumors, < 3 cm, without lymphovascular invasion, the risk of nodal involvement was very low, suggesting that this Western cohort could be considered for endoscopic resection.