[Expression of oncogenes C-myc, C-raf and N-ras in advanced cancers of the upper respiratory and digestive tracts. Correlation with tumor clinical response to chemotherapy].

: A correlation between oncogenes expression (N-ras, C-myc, C-raf) and response to neoadjuvant chemotherapy has not been established in carcinology of the head and neck yet. We have studied the expression of these three oncogenes in 24 tumors patients with squamous cell carcinoma previously untreated. Tumors samples were biopsed before initiation of treatment. After extraction of total RNAs, oncogene expression was measured by northern and slot blot analysis using 32P radiolabeled probes. The endoscopic, histological and clinical response was evaluated after chemotherapy (5-FU: 1 g/m2/d, D1 to D5; CDDP: 100 mg/m2 at D1, 3 courses every 3 weeks). There was no significant difference of N-ras expression between responding or resistant tumors to chemotherapy. However, there was a significant difference of C-myc (p < 0.05) and C-raf (p < 0.01) expression between the two patients population: C-raf and C-myc expression were higher in the responding tumors than in the resistant tumors to chemotherapy. In conclusion, C-myc and C-raf expression could be a marker for chemosensitivity.