Patients in this arm will be assigned to a 12-week exercise intervention twice weekly based on Nordic Walking (NW). The intervention will be structured as follows: i) 10 min warm-up, ii) 40 min NW with muscle strengthening exercises interspersed in between and iii) 10 min cool-down. Intensity will be monitored with a heart rate monitor (when available) and/or Borg Scale to reach a moderate intensity for the first 6 weeks (4 - 6 or 55-65% HR reserve) to a moderate-to-high intensity the following weeks (7 - 8 or 65-75% HR reserve).

Patients in this group will be assigned to a 12-week, twice weekly water-based exercise programme to be conducted at a chest-high swimming pool kept around 30 to 32 degrees Celsius. Each session will be structured as previous: i) 10 min warm up; ii) 40 min of combined endurance and strength exercise training and iii) 10 min cool down. Intensity will be monitored using the Borg Scale to be moderate during the first 6 weeks (4 - 6) and moderate-to-high the following 6 weeks (7-8).

In this group, patients will participate in a traditional, circuit-based exercise training at a fitness facility twice daily during 12 weeks. Each session will consist of: i) 10 min warm up; ii) 40 min of combined resistance and endurance training using a circuit-based structure and iii) 10 min cool-down. Intensity will be monitored with a HR monitor (when available) and/or Borg Scale to reach a moderate intensity for the first 6 weeks (4 - 6 or 55-65% HR reserve) and will progress to moderate-to-high over the following weeks (7-8 or 65-75% HR reserve).

A 12-week Nordic Walking exercise programme supervised twice weekly

HRQoL measured with the EORTC Quality of Life C30 questionnaire

Cancer-related fatigue as measure with the Brief Fatigue Inventory

A steady state cardiopulmonary exercise testing with breath-by-breath analysis and lactate measurement to determine submaximal cardiorespiratory fitness