Lack of claudin-7 is a strong predictor of regional recurrence in oral and oropharyngeal squamous cell carcinoma.

OBJECTIVES: Adequate treatment of oral and oropharyngeal squamous cell carcinoma (OSCC) is dependent on correctly predicting the presence of lymph node metastases. Current methods to diagnose nodal metastases partly result in overtreatment with associated morbidity and undertreatment with decreased disease-free survival. E-cadherin has been studied extensively as potential marker for lymph node metastases. EpCAM and claudin-7 have a functional relationship with E-cadherin, forming a complex that promotes tumourigenicity in vitro. We hypothesize that the co-expression patterns of these related molecules is a better prognostic marker for nodal status and regional recurrences.
MATERIALS AND METHODS: We constructed separate tissue microarrays of tumour centre and tumour invasive front of 227 OSCC with complete clinicopathological and follow-up data, including HPV status, and performed immunohistochemistry for these molecules.
RESULTS: Lack of E-cadherin and presence of cytoplasmic EpCAM expression in the tumour front were predictive for nodal metastasis, but no co-expression pattern was found clinically relevant. Lack of claudin-7 in the tumour centre was highly and independently predictive for shorter regional disease-free survival (HR=0.19; 95%CI: 0.06-0.62) and disease-specific survival (HR=0.43; 95%CI: 0.21-0.87). High-risk HPV was not associated with any marker.
CONCLUSIONS: The expression of E-cadherin and EpCAM, depending on the specific tumour sublocalization, is predictive for nodal status. However, co-expression did not improve the prediction of nodal status, indicating that the proposed in vitro complex is not functional in clinical samples. Additionally, lack of claudin-7 expression in the tumour centre may be used to identify patients with increased risk for regional recurrence.