Low Mast Cell Density Predicts Poor Prognosis in Oral Squamous Cell Carcinoma and Reduces Survival in Head and Neck Squamous Cell Carcinoma.

BACKGROUND: The cellular composition of the tumor microenvironment (TME) at the invading front of oral squamous cell carcinomas (OSCCs) may reflect biologically important cancer features and host responses, and thus be related to disease progression. The TME density of mast cells (MCs), macrophages, cancer-associated fibroblasts (CAFs) and endothelial cells were quantified at the invasive front and analyzed regarding their relation to disease recurrence in patients with small T1/2N0M0 OSCCs. mRNA for MC-specific proteins were analyzed in a second patient cohort with head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS: Samples from 62 patients with T1/2N0M0 OSCC were immunohistochemically stained and scored for the cellular expression of mast/stem cell growth factor receptor (c-KIT) (MCs), CD68 (macrophages), α-smooth muscle actin (α-SMA) (CAFs) and CD31 (endothelial cells) and this was analyzed according to disease recurrence. Data from The Cancer Genome Atlas database were used to examine mRNA expression profiles and clinical data of patients with 399 HNSCC. RESULTS: Increased MC density at the invasive front was significantly associated with reduced disease recurrence, as none of the patients with high MC density experienced relapse. Moreover, increased expression of mRNA for MC specific markers as c-KIT, and α-, ß-, and δ-tryptases and the MC-stimulating factor, stem cell factor (SCF), was significantly associated with good prognosis in patients with HNSCC. CONCLUSION: Decreased MC density at the invasive front may reflect tumor biology related to disease progression and prognosis. Counting MCs seems to be an easy and practical tool, that could be utilized for prognostic evaluation.

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

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.