[Examination of ERCC1 expression in lung cancer patients treated with platinum-based chemotherapy]

Platinum-based chemotherapies are widely used in the treatment of lung cancer. However, little is known about their effect in the expression of certain tissue biomarkers. We have studied the ERCC1 (excision repair cross-complementation group 1) expression in tissue samples of patients treated with neoadjuvant chemotherapy. Fifty lung cancer tissue blocks of 25 patients (15 males, 10 females) were studied. They included 25 bronchoscopic biopsies (14 squamous cell carcinomas and 11 adenocarcinomas) together with their corresponding surgical biopsies after neoadjuvant chemotherapy. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissues to study the expression of ERCC1. Staining scores (0-300) were calculated by multiplying the percentage of positive tumor cells (0-100) by the staining intensity (0-3). All but one bronchosopic squamous cell carcinoma tissues (13/14) expressed ERCC1. Four of these cases became negative after neoadjuvant therapy, and in 8 cases the level of expression decreased. In the adenocarcinoma group all but one bronchosopic tissues (10/11) expressed ERCC1. Six of these cases became negative after neoadjuvant therapy, and in 4 cases the level of expression decreased. Comparison of staining scores before and after chemotherapy revealed more pronounced decrease in adenocarcinomas and in female patients. There was no newly expressed ERCC1-positive case in the surgical biopsy group. The results of the present study suggest that platinum-based chemotherapy affects the expression of tissue biomarker (ERCC1) which may have predictive value, and probably induces a selection of tumor cells with more aggressive phenotype. This knowledge might be of importance when designing treatment protocols for non-small cell lung cancer patients.