Prognostic significance of CD44 and CK19 expression in head and neck squamous cell carcinoma

Purpose of the study . To analyze and synthesize current scientific evidence on the role of CD44 and CK19 expression in the pathogenesis of head and neck squamous cell carcinoma (HNSCC), their diagnostic and prognostic significance, as well as their potential clinical applications and future perspectives. Materials and methods . The review was based on an analysis of publications from PubMed, Scopus, Web of Science, and Embase using the following keywords: “head and neck squamous cell carcinoma”, “CD44”, “CK19”, “biomarker”, and “prognosis”. The inclusion criteria comprised original studies and meta-analyses; duplicate and irrelevant publications were excluded. Methods for detecting CD44 and CK19, as well as the clinical and demographic characteristics of the studied cohorts, were compared across the included studies. Results . Increased or aberrant CD44 expression was associated with greater tumor aggressiveness, a higher risk of recurrence and metastasis in HNSCC, while specific isoforms (CD44v4, CD44v6) may indicate therapeutic resistance and an unfavorable disease course. CD44 expression was influenced by several factors, including tumor site, age, and sex. Elevated CK19 levels were associated with poor differentiation, higher malignancy, and an increased risk of recurrence; this marker was frequently detected in HPV-associated tumors. Immunohistochemical and molecular assays for CK19 demonstrated high sensitivity and specificity. Recent studies confirm that the combined assessment of CD44 and CK19 improves the accuracy of risk stratification and clinical monitoring in HNSCC. Conclusion . CD44 and CK19 are promising biomarkers for a personalized approach to the diagnosis and management of patients with HNSCC. Their combined use improves early risk stratification for disease progression and recurrence, as well as the selection of optimal treatment strategies. Further large-­scale studies and methodological standardization are required to implement these biomarkers in clinical practice to improve patient survival and quality of life.