- Week 1: inclusion and first visit. The patients will be contacted (phone call) by an investigator who will provide explanations about the study. Notably, the investigator will explain that the patients will be allocated randomly to one of two study arms and that they may not chose which one they will be allocated to. In addition, the investigator will check eligibility through a brief questionnaire-based interview. Patients who meet the inclusion criteria will be invited to come to the Luxembourg Institute of Health (Strassen, Luxembourg) for the first visit. During this first visit (duration: 90 min), patients will be asked to sign the written informed consent. Then, patients will be asked to fill in several questionnaires available in English, French, German and Portuguese: three background questionnaires and one cancer-specific health related quality of life (HRQoL) questionnaire (EORTC-QLQ30). Height and weight will be measured. Patients will subsequently perform physical fitness tests, including ramped Bruce protocol test on a treadmill, leg strength and grip strength tests. Finally, patients will receive a 3D-accelerometer (Actigraph) measuring physical activity behaviour, which they will have to wear for one week. Further details one these methodologies are provided below.