Cancer stem cell enrichment marker CD98: a prognostic factor for survival in patients with HPV-positive oropharyngeal cancer

Objective: Several hypotheses have been proposed to explain the relatively good prognosis of patients with an HPV-positive oropharyngeal squamous cell carcinoma (OPSCC) and one of these is a higher sensitivity to (chemo)radiation. Previous studies have suggested that treatment failure in OPSCC patients is caused by resistance of cancer stem cells (CSCs). The purpose of this study was to evaluate the association between the percentage of CSCs and prognosis in patients with an HPV-positive OPSCC. Methods: All OPSCC patients (n=711) treated between 2000 and 2006 in two Dutch university hospitals were included. Presence of HPV in a tumor tissue specimen was tested by p16-immunostaining followed by an HPV DNA GP5+/6+-PCR. The presence and intensity of tumor CSC markers CD44 and CD98 were determined by immunohistochemistry and semiquantitative scoring was performed. Overall survival (OS) and progression-free survival (PFS) rates were compared between patients with low and high CD44/CD98 expression in relation to HPV status.