Impact of extranodal tumor deposits on prognosis and N stage in gastric cancer

Background: Extranodal tumor deposits have been reported to be associated with a poor prognosis in many malignancies and are also included in the tumor, node, and metastasis staging system for colorectal cancer. Methods: We reviewed retrospectively a total of 2,344 gastric cancer patients who underwent gastrectomy with curative intent at the Tianjin Medical University Cancer Institute and Hospital (Hexi District, Tianjin, China) and the First Affiliated Hospital of Hainan Medical University (Longhua District, Haikou, China). Patients were categorized into 2 groups based on extranodal-tumor deposit status: a positive group, including those with extranodal tumor deposits, and a negative group composed of those with no extranodal tumor deposits. Clinicopathologic factors were correlated with extranodal tumor deposits, and their individual prognoses were analyzed. In addition, a pathologically modified node classification system was proposed by incorporating the extranodal tumor deposit status into the 8th ed of the N staging system. The superiority of prognostic prediction between the modified node classification and node stage was compared. Results: A total of 645 (27.5%) patients had extranodal tumor deposits. The presence of extranodal tumor deposits was associated with a larger tumor size, Borrmann type III and IV, a deeper depth of invasion, and an advanced node stage. In the multivariate analysis, extranodal tumor deposits were an independent prognostic factor for gastric cancer patients after curative resection. Gastric cancer patients with extranodal tumor deposits demonstrated a lesser 5-year overall survival than those with no extranodal tumor deposits (31.9% vs 61.4%, P < .001). With the strata analysis, statistically significant prognostic differences between the two groups were only observed in patients at the N0-N2 stage. The modified node classification was found to be more appropriate for predicting the overall survival of gastric cancer patients after curative resection than node stage, and the -2 log likelihood of the modified node classification (16,042.890) was smaller than the value of node stage (16,150.811). Conclusion: Extranodal tumor deposits in gastric cancer patients indicate aggressive characteristics and a poorer prognosis of gastric cancer. We maintain that extranodal tumor deposits should be incorporated into the N staging system to enhance the accuracy of the prognostic prediction of patients with gastric cancer. (C) 2019 Elsevier Inc. All rights reserved.