Lack of CD44 overexpression and application of concurrent chemoradiotherapy with cisplatin independently indicate excellent prognosis in patients with HPV-positive oropharyngeal cancer.

Background: HPV-16 positivity in patients with squamous cell carcinoma of oropharynx (OPSCC) is associated with better prognosis. However, in more than 40% of HPV infected patients progression of cancer disease is observed, which indicates the presence of cancer cells resistant to therapy. Some studies suggest that there may be a subpopulation of cancer stem cells (CSCs), which simultaneously exhibit unlimited ability to self-renew and differentiate towards neoplastic cells. The relation between HPV16 infection and biomarkers of CSCs is unclear.
Objective: The aim of the study was to compare the expression of CD44, CD98, ALDH1/2 and P16 in oropharyngeal cancer patients with or without HPV16 infection, as well as to analyze the prognostic potential of selected CSCs biomarkers in these two subgroups.
Methods: The study was performed in a group of 63 patients. HPV16 infection status was analyzed by quantitative polymerase chain reaction, while CD44, CD98, ALDH1/2 and P16 expression by immunohistochemistry. In survival analysis, two endpoints were applied: overall survival (OS) and disease-free survival (DFS).
Results: Among 63 cancers, HPV16 infection was found in 25 tumors (39.7%), overexpression of CD44, CD98, ALDH1/2 and P16 in 43 (68.2%), 30 (47.6%), 33 (52.4%) and 27 (42.9%) cancers, respectively. In the HPV16-positive subgroup, DFS rate of 100% was observed in patients with tumors characterized by lack of CD44 overexpression and those treated with concurrent chemoradiotherapy with cisplatin (CisPt-CRT). In the HPV16-negative subgroup 100% of DFS was noticed for patients (n = 6) with P16 immunopositive tumors. In this subgroup none of the CSCs biomarkers evaluated in the study had any impact on OS or DFS. In patients with HPV16-positive oropharyngeal cancer, lack of CD44 overexpression and application of CisPt-CRT were found to be positive prognostic factors.