Number of subjects: Taking alpha=5% and bêta=7.5% with 10% patients not evaluable after randomisation, 236 patients (118 patients/arm) must be enrolled to show a 50% increase in the main endpoint at 3 years (from 20% to 40%).This study will show a hazard ratio of 0.56. Stopping rule: non-salvageable local recurrence rate > 10% checked by the independent Data Monitoring Committee every 80 patients.