Integrating Tumor Budding and the Invasive-Front Microenvironment in Colorectal Carcinoma: An Exploratory Histopathological Score-Based Association Study

The invasive tumor front (ITF) of colorectal carcinoma (CRC) is a biologically active interface where epithelial dissociation, stromal activation, immune remodeling, and angiogenesis converge. This retrospective histopathological association study examined whether tumor budding combined with selected ITF microenvironmental markers could better characterize aggressive clinicopathological features of non-metastatic CRC. Fifty-two surgically resected primary CRCs were analyzed after exclusion of patients with distant metastatic disease at diagnosis or surgery. Tumor budding was scored according to ITBCC 2016 criteria. Immunohistochemistry evaluated stromal podoplanin (D2-40) expression, CD34-based microvessel density, the CD163/CD68 ratio, and CD117-positive mast cell density. An unweighted integrated ITF microenvironment score (0-4) was generated by summing high values for these four parameters. High histological grade, lymphovascular invasion, high tumor budding, and node-positive disease were significantly associated with multiple microenvironment-related alterations. The integrated ITF score was significantly higher in high-grade, lymphovascular invasion-positive, node-positive, and high-budding CRCs, suggesting cumulative stromal, immune, and vascular remodeling at the invasive front. These findings support the ITF as an integrated histopathological compartment in CRC progression. However, the score remains hypothesis-generating and requires validation in larger, independent, molecularly and outcome-annotated cohorts before prognostic or clinical use.