Risk of Lymph Node Metastasis in T1b Gastric Cancer: An International Comprehensive Analysis from the Global Gastric Group (G3) Alliance.

OBJECTIVE: We sought to define criteria associated with low lymph node metastasis risk in patients with submucosal (pT1b) gastric cancer from 3 Western and 3 Eastern countries. SUMMARY BACKGROUND DATA: Accurate prediction of lymph node metastasis risk is essential when determining the need for gastrectomy with lymph node dissection following endoscopic resection. Under present guidelines, endoscopic resection is considered definitive treatment if submucosal invasion is only superficial, but this is not routinely assessed. METHODS: Lymph node metastasis rates were determined for patient groups defined according to tumor pathological characteristics. Clinicopathological predictors of lymph node metastasis were determined by multivariable logistic regression and used to develop a nomogram in a randomly selected subset that was validated in the remainder. Overall survival was compared between Eastern and Western countries. RESULTS: Lymph node metastasis was found in 701 of 3166 (22.1%) Eastern and 153 of 560 (27.3%) Western patients. Independent predictors of lymph node metastasis were female sex, tumor size, distal stomach location, lymphovascular invasion, and moderate or poor differentiation. Patients fulfilling the National Comprehensive Cancer Network guideline criteria, excluding the requirement that invasion not extend beyond the superficial submucosa, had a lymph node metastasis rate of 8.9% (53/594). Excluding moderately differentiated tumors lowered the rate to 3.4% (10/296). The nomogram's area under the curve was 0.690. Regardless of lymph node status, overall survival was better in Eastern patients. CONCLUSIONS: The lymph node metastasis rate was lowest in patients with well differentiated tumors that were ≤3 cm and lacked lymphovascular invasion. These criteria may be useful in decisions regarding endoscopic resection as definitive treatment for pT1b gastric cancer.

Pathology definitions and resection strategies for early colorectal neoplasia: Eastern versus Western approaches in the post-Vienna era.

There is a well-known discrepancy between East and West classifications of colorectal neoplasm, especially "intramucosal carcinoma," categorized as subgroup 4.4 in the Vienna classification, usually recognized as high-grade dysplasia in the United States and as carcinoma in situ in Japan. Focusing on management, in the current National Comprehensive Cancer Network algorithm, high-grade dysplasia, carcinoma in situ, and intramucosal carcinoma are managed similarly, whereas submucosal invasion by carcinoma requires en bloc resection. To bridge the differences with regard to these conceptual problems in the definition and management of carcinoma in situ and intramucosal carcinoma, endoscopists and pathologists from Japan and the United States gathered and discussed from their perspectives how to accurately assess specimens of en bloc/piecemeal resection and to effectively predict lymph node metastasis risk.