Purpose: The excision repair cross-complementing 1 (ERCC1) gene is coding for a nucleotide excision repair protein involved in the repair of radiation-and chemotherapy-induced DNA damage. We examined the potential of quantitative ERCC1 mRNA expression to predict minor or major histopathological response to neoadjuvant radiochemotherapy (cisplatin, 5-fluorouracil, and 36 Gy of radiation) followed by transthoracic en bloc esophagectomy in patients with locally advanced esophageal cancer (cT 2-4 , N x , M 0 ).Experimental Design: Tissue samples were collected by endoscopic biopsy before treatment. RNA was isolated from biopsies, and quantitative real-time reverse transcriptase PCR assays were performed to determine ERCC1 mRNA expression. Relative mRNA levels (tumor/normal ratios) were calculated as (ERCC1/-actin in tumor)/(ERCC1/ -actin in paired normal tissue). ERCC1 expression levels were correlated with the objective histopathological response in resected specimens. Histomorphological regression was defined as major response when resected specimens contained <10% of residual vital tumor cells or in case a pathologically complete response was achieved.Results: Twelve of 36 tumors showed a major histopathological response, and 24 of 36 showed a minor histopathological response. Relative expression levels of ERCC1 of >1.09 were not associated with a major histopathological response (sensitivity, 62.5%; specificity, 100%) and 15 of 24 patients with minor histopathological response to the delivered neoadjuvant radiochemotherapy could be unequivocally identified. This association of dichotomized relative ERCC1 mRNA expression and histopathological response was statistically significant (P < 0.001).Conclusions: Relative expression levels of ERCC1 mRNA determined by quantitative real-time reverse transcriptase-PCR appear highly specific to predict minor response to our neoadjuvant radiochemotherapy protocol in patients with locally advanced esophageal cancer and could be applied to prevent expensive, noneffective, and potentially harmful therapies in a substantial number (42%) of patients.
Patients with locally advanced esophageal cancer have a dismal prognosis when treated exclusively by surgery. This fact prompted many investigators to apply neoadjuvant treatment strategies in an effort to improve survival. Results from phase III randomized trials are encouraging however, they revealed that only patients with major histopathological response will benefit from treatment. Therefore, predictive molecular markers indicating response or non-response to neoadjuvant treatment would be extremely helpful in selecting patients for current and future treatment protocols. In this paper we review the role of the molecular markers ERCC1 (excision repair cross-complementing 1 gene) and c-erbB-2 (synonym: HER2/neu) in predicting response to radiochemotherapy and outcome for patients with locally advanced resectable esophageal cancers (cT2-4, Nx, M0). The results are promising and it appears that we might expect to unequivocally identify with ERCC1 and c-erbB-2 respectively, approximately up to one third of patients who fulfil the criteria for neoadjuvant treatment for locally advanced esophageal cancer but will not benefit from our treatment protocol. Integration of such markers in the clinical setting might prevent a substantial number of patients from expensive, non-effective and potentially harmful therapies, and could lead to a more individualized type of combined multimodality treatment in the near future.
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