Soluble CD44v6 is Not a Sensitive Tumor Marker in Patients with Head and Neck Squamous Cell Cancer

Background: In some epithelial tumors, isoforms of CD44 are overexpressed and soluble isoforms detectable in serum samples are elevated. In squamous cell cancer of the head and neck (SCCHN) the alteration of CD44 isoforms could be associated with poor prognosis. A comprehensive study was undertaken to examine the value of CD44v6 as a tumor marker for SCCHN. Patients and Methods: Serum samples of SCCHN and healthy smokers were analyzed for soluble CD44v6 by ELISA. The expression of CD44 isoforms was determined by immunohistochemical staining of healthy and dysplastic tissue. Results: There was no significant difference between the serum levels of sCD44v6 in SCCHN and healthy smokers. Nor was there a correlation between the serum level of sCD44v6 and UICC stage, TNM stage or histological grading. In tissue of primary SCCHN, expression of CD44v6 was found as a strong, specific staining of the lower epithelial layers. Similar amounts of CD44v6-positive-labelled tumor cells were found in invasive carcinoma. Conclusion: Soluble CD44v6 is not a valuable tumor marker for SCCHN since the soluble form appears to be present in healthy smokers and does not reflect the stage of the disease.