ERCC1 – Locoregional differences in prognostic value of ERCC1 expression in patients with head and neck squamous cell carcinoma.

Purpose: The analysis of nucleotid excision repair (NER) molecule expression in head and neck squamous cell carcinoma (HNSCC) have been under investigation for a long time considering platinum based chemotherapy resistance but yet have not found their way into clinical practice. ERCC1 is known to be one of the speed limiting proteins in DNA repair. Therefore we investigated the role of ERCC1 expression as a prognostic factor in patients with HNSCC by looking at overall and recurrence free survival. Material and Methods: Tissue microarrays were constructed from tumor blocks from 294 patients. ERCC1 expression was determined by immunohistochemistry using the 4F9 antibody. Expression levels were dichotomized into a high and low ERCC1 expressing group followed by a comparison of age, gender, TNM status, Grading and UICC stage. Outcomes for overall survival and recurrence free survival were analyzed by using the Kaplan-Meier method and performed for different subsites of the head and neck. Results: Contradicting most papers published we could show that there was no correlation between ERCC1 expression and overall or recurrence free survival by looking at all HNSCC. But further subsite analysis revealed that a high ERCC1 expression was associated with an inferior overall survival in patients with SCC of the oral cavity (Median 15,4 months vs. 59,8 months p=0,028). Statistical analysis of the oropharynx, hypopharynx and larynx showed no difference between the high and low ERCC1 expressing groups. Looking at age, gender, T, M and UICC stage there was no statistical significant difference. Regarding N stage, high ERCC1 expression was found to be associated with progressive nodal disease (>pN1; p=0,0499). Conclusions: ERCC1 functions as a predictive marker for overall survival in patients with squamous cell carcinoma of the oral cavity but not of other subsites in the head and neck. The effect of a high ERCC1 expression correlating with inferior survival looking at all subsites in the head and neck tumors could not be shown as described in literature suggesting different behavior of tumors in different subsites. Therefore further studies have to be done to add more information to potential predictive markers for SCC in the head and neck.