Résumé : Background and purpose The aim of this study was to assess the efficacy of a 38-h communication skills training program designed for multidisciplinary radiotherapy teams. Materials and methods Four radiotherapy teams were randomly assigned to a training program or to a waiting list. Assessments were scheduled at baseline (T1) and then after the training was completed or four months later (T2), respectively. Communication around radiotherapy delivery was assessed based on audio recordings of the first and last radiotherapy sessions in order to assess team members' communication skills and the expression of concerns by breast cancer patients (analyzed with content analysis software LaComm). Results 198 radiotherapy sessions were recorded. During the first radiotherapy sessions, members of the trained teams exhibited more assessment skills (p = 0.048), provided more setting information (p < 0.001), and used more social words (p = 0.019) compared to the members of the untrained teams. During the last radiotherapy session, members of the trained teams used more assessment skills (p = 0.004) and patients interacting with members of the trained teams expressed more sadness words (p = 0.023). Conclusion Training of multidisciplinary teams has the potential to transfer skills that affect the short exchanges that take place around radiotherapy delivery.