Enrichment of Cells with Cancer Stem Cell-Like Markers in Relapses of Chemoresistant Patients with Locally Advanced Head and Neck Squamous Cell Carcinoma

Background: Patients with head and neck squamous cell carcinoma (HNSCC) present different responses to chemotherapy and radiotherapy. One explanation may be the differences in the individual rates of stem cell-like cells. Methods: We included patients with HNSCC and tumor progression or relapse. Tumor samples were obtained before and after primary chemotherapy, and immunohistochemical analyses were performed for CD44, HLA class I (HLA-I), pancytokeratin, and phosphorylated epidermal growth factor receptor (p-EGFR). Differences in expression between the first and second specimens were assessed. Results: Expression between the first and second specimens varied as follows: CD44 increased by 14.67% (95% confidence interval, CI: 6.94 to 22.40; p < 0.01); HLA-I decreased by 16.72% (95% CI: -23.87 to -9.47; p < 0.01); pancytokeratin decreased by 24.91% (95% CI: -32.8 to -17.7; p < 0.01), and p-EFGR expression decreased by 12.30% (95% CI: -20.61 to -3.98; p < 0.005). Conclusions: Among patients with HNSCC, there is an enrichment of cells with stem-like markers in relapsed tumors when compared with the primary tumor. This finding should be considered when developing treatment strategies.