https://www.selleckchem.com/products/KU-55933.html Local protocols for perioperative care in each participating hospital will determine into which cohort a patient is placed. The primary outcome is cost-effectiveness, which will be calculated by comparing all healthcare costs with the quality-adjusted life-years (QALYs, calculated using EQ-5D questionnaires). Secondary outcomes are mortality, complications within 30 days after surgery, readmissions, reoperations, length of stay, weight loss, generic quality of life (QOL), OSA-specific QOL, OSA symptoms and CPAP adherence. Patients will receive questionnaires before surgery and 1, 3, 6 and 12 months after surgery to report QALYs and other patient-reported outcomes. Approval from the Medical Research Ethics Committees United was granted in accordance with the Dutch law for Medical Research Involving Human Subjects Act (WMO) (reference number W17.050). Results will be submitted for publication in peer-reviewed journals and presented at (inter)national conferences. NTR6991. NTR6991. Exercise interventions have been widely investigated in patients with cancer and demonstrate beneficial effects. However, intervention studies that include older women with breast cancer exercising during medical treatment are scarce. Hence, the aim of this study is to investigate the effect of a 12-week exercise-based intervention in older women (≥65 years) with breast cancer receiving (neo)adjuvant or first-line or second-line systemic therapy. This is a single-centre, two-armed randomised controlled trial. We anticipate including 100 patients, who will be randomised 11 to exercise-based intervention or control stratified by treatment setting ((neo)adjuvant or metastatic) and treatment (chemotherapy or endocrine therapy + cyclin-dependent kinase (CDK) 4/6 inhibitors). The intervention group will receive standard oncological treatment and a 12-week supervised exercise-based intervention comprising a progressive resistance exercise programme