Purpose: To assess the correlation of excision repair cross complementation group 1 (ERCC1) immunohistochemical expression with objective tumor response and cancer-specific survival in patients with locally advanced head and neck squamous cell carcinoma treated with cisplatinbased induction chemotherapy. Experimental Design: The initial cohort was composed of 107 patients who were treated from 1992 to 1996 by an induction chemotherapy regimen for locally advanced head and neck squamous cell

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... inoma. p53 mutations had previously been studied. Pretherapeutic biopsy samples from 96 patients with a known tumor response were available. Two independent observers blinded to clinical annotations evaluated ERCC1immunohistochemical expression. Results: Of 96 patients, 68 (71%; 95% confidence interval, 61-79%) had tumors that expressed ERCC1intensively and diffusely. Using the logistic regression method, the 28 (29%) patients with tumors expressing ERCC1at lower levels had a 4-fold greater odds of benefiting from an objective response to chemotherapy (odds ratio, 4.3; 95% confidence interval, 1.4-13.4; P = 0.01) compared with the group of 68 patients with high ERCC1expression. ERCC1and p53 status, but not their interaction, were independent predictors of tumor response. In a Cox proportional hazard model adjusted on age, TNM stage, tumor differentiation, and tumor localization, ERCC1 low expression was associated with a lower risk of cancer death (risk ratio, 0.42; 95% confidence interval, 0.20-0.90; P = 0.04) whereas p53 status had no prognostic value. Conclusion: Our results suggest that those patients characterized by low ERCC1expression are more likely to benefit from cisplatin induction chemotherapy compared with patients with high ERCC1expression.