Tumor Budding, EMT and Cancer Stem Cells in T1-2/N0 Oral Squamous Cell Carcinomas

Abstract

Background: Early oral carcinomas have a high recurrence rate despite surgery with clear margins. In an attempt to classify the risk of recurrence of oral squamous cell carcinomas, we explored the significance of tumor budding, epithelial-mesenchymal transition (EMT) and certain cancer stem cell markers (CSC).

Materials and methods: Tumor budding (single cells or clusters of ≤5 cells in the tumor front, divided into high- and low-budding tumors), EMT and CSC markers were studied in 62 immunohistochemically stained slides of T1/2N0M0 oral squamous cell carcinomas. Tissues and records of follow-up were obtained from the Oslo University Hospital, Norway. Tumor budding, EMT and CSC markers were scored and analyzed.

Results: The only significant prognostic marker was tumor budding (p=0.043). Expression of the EMT marker E-cadherin was lost from the invasive front and tended to be a prognostic factor (p=0.17), and up-regulation of vimentin in tumor cells in the invasive front was found; this indicates that EMT had occurred. CSC markers were not associated with recurrence rate in the present study.

Conclusion: A high budding index was related to poor prognosis in patients with oral cancer. Budding was associated with EMT-like changes. CSC factors were detected but reflected differentiation rather than stemness. Scoring of buds in patients with oral cancer may help discriminate invasive tumors prone to relapse, and thus, provide an indication for adjuvant therapy.

Keywords: CSC; EMT; Oral squamous cell carcinoma; prognosis; tumor budding.