Prognostic Ability of Tumor Budding Outperforms Poorly Differentiated Clusters in Gastric Cancer

Simple Summary Small clusters of tumor cells at the invasion front of the tumor, known as "tumor budding" and larger clusters of cells, known as "poorly differentiated clusters", are well known histological parameters to assess the outcome of colorectal cancer. However, their prognostic value for gastric cancer is less well investigated and controversial based on the studies conducted so far. In our retrospective study, we investigated the prognostic power of these two entities in a large cohort of gastric cancer patients. Our results demonstrate that tumor budding is an independent prognostic factor determining overall survival in gastric cancer, especially in intestinal type adenocarcinomas. In addition, budding can also predict the risk of lymph node metastases. However, although the trend is similar for poorly differentiated clusters, their predictive value is lower and they have not been shown to be an independent prognostic factor of survival in gastric cancer. The prognostic value of histological phenomena tumor budding (TB) and poorly differentiated clusters (PDCs) have been less studied in gastric cancer (GAC) and the data provided so far are controversial. In our study, 290 surgically resected GAC cases were evaluated for TB according to the criteria of International Tumor Budding Consensus Conference (ITBCC) and PDC, and both parameters were scored on a three-grade scale as described for colorectal cancer previously (0: Grade0, 1-4: Grade1, 5-9: Grade2 and >= 10: Grade3) and classified as low (Grade0-2) and high (Grade3) TB/PDC. High TB/PDC was associated with diffuse-type morphology, higher pT status, incomplete surgical resection, poor tumor differentiation and perineural and lymphovascular invasion. Multivariable survival analyses have shown an independent prognostic role of high TB with poorer overall survival in the total cohort (p = 0.014) and in intestinal-type adenocarcinomas (p = 0.005). Multivariable model revealed high TB as an independent predictor for lymph node metastasis in both the total cohort (p = 0.019) and in the intestinal type adenocarcinomas (p = 0.038). In contrast to tumor budding, no significant association was found between PDC and the occurrence of lymph node metastasis and tumor stage and even survival. In conclusion, tumor budding is an independent prognostic factor of survival in gastric cancer, especially in intestinal-type adenocarcinomas.