Prognostic Value of Measuring CtDNA in a Cohort of Patients With Stage III and IV Upper Aero-digestive Tract (UADT) Cancer , Treated With Curative RADiOtherapy With or Without Concomitant Treatment.

"A blood sample of 20 mL (2 tubes of 10 mL) for research purposes will be collected during:~* The day of the centering scan (Visit 1);~* During treatment at Week 2 and Week 6 (+/- 1 week) (Visit 2 and 3);~* The day of the post-therapeutic visit scheduled between 3 and 5 weeks after the end of radiotherapy, whether or not associated with concomitant treatment (Visit 4);~* At each monitoring visit following radiotherapy associated or not with concomitant treatment (every 3 months for 24 months (V5 to V12 ; V12 = final visit)~* When the disease progresses before initiation of the 2nd line of treatment."