Experimental: Prehabilitation group

The intervention group will participate in a prehabilitation program of approximately 4-6 weeks before surgery, and additionally during neoadjuvant chemotherapy if applicable. The program consist of a tailored exercise program, nutritional support and if relevant smoking cessation and/or psychological counselling. The exercise program is under supervision of an oncology specialized physiotherapist and comprises aerobic-, resistance- and breathing- and relaxation exercises. A dietician will provide nutritional support and give dietary advice to increase protein intake, including a supplement containing 30 g of whey-protein daily and after supervised training. Patients who score high on anxiety and depression will be offered a referral to a psychologist. Intensive counselling and nicotine replacement therapy will be offered to all patients who smoke.~Patients will be asked to keep a diary to track unsupervised activity and to track intake of the protein supplementation.

No_intervention: Control group

Patients randomized to the control group will receive care as usual according to local ERAS guideline implementation. In addition, they will receive a leaflet with the recent guidelines regarding physical activity, dietary advice, and smoking cessation. Their actual physical activity level will be obtained via questionnaire.