Expression of Cancer Stem Cell Biomarkers in Human Head and Neck Carcinomas: a Systematic Review.

Malignant neoplasms may be composed of several cell groups, including cancer stem cells (CSC). These cells have been related with the capacity of metastasis, relapse and resistance to multiple drugs during chemotherapy. This study aims to identify CSC biomarkers and their expression pattern in human head and neck carcinomas. This study was conducted following the PRISMA checklist. The search for articles was carried out in five databases (PubMed, Scopus, Web of Science, Lilacs and Scielo). The articles found were selected in two phases: 1) reading the titles and / or abstract and 2) reading the full text. At the end, the selected articles were evaluated by QUADAS-2. Most studies evaluated oral neoplastic tissues and, as a control, samples of normal local mucosa. All studies performed immunohistochemistry as a method of immunolocalization and some also applied immunofluorescence. The most commonly used biomarker was CD44. However, other such as Sox2, Oct4, Nestin, Nanog, BMI1, ALDH1, CD133 and CD166 were also found. Several biomarkers were (ALDH1, Sox2, Oct4, ABCB5, AGR2 and TAZ) correlated with clinical characteristics of the tumor, such as staging, tumor size and lymph node metastasis. These data reinforce the CSC theory and favor the use of these biomarkers as possible determinants of prognosis.