The Relationship Between Tumor Budding, Tumor Microenvironment, and Survival in Patients with Primary Operable Colorectal Cancer.

Background: Tumor budding is an independent prognostic factor in colorectal cancer (CRC) and has recently been well-defined by the International Tumour Budding Consensus Conference (ITBCC).

Objective: The aim of the present study was to use the ITBCC budding evaluation method to examine the relationship between tumor budding, tumor factors, tumor microenvironment, and survival in patients with primary operable CRC.

Methods: Hematoxylin and eosin-stained slides of 952 CRC patients diagnosed between 1997 and 2007 were evaluated for tumor budding according to the ITBCC criteria. The tumor microenvironment was evaluated using tumor stroma percentage (TSP) and Klintrup-Makinen (KM) grade to assess the tumor inflammatory cell infiltrate.

Results: High budding (n = 268, 28%) was significantly associated with TNM stage (p < 0.001), competent mismatch repair (MMR; p < 0.05), venous invasion (p < 0.001), weak KM grade (p < 0.001), high TSP (p < 0.001), and reduced cancer-specific survival (CSS) (hazard ratio 8.68, 95% confidence interval 6.30-11.97; p < 0.001). Tumor budding effectively stratifies CSS stage T1 through to T4 (all p < 0.05) independent of associated factors.

Conclusions: Tumor budding effectively stratifies patients' survival in primary operable CRC independent of other phenotypic features. In particular, the combination of T stage and budding should form the basis of a new staging system for primary operable CRC.