Effects of intravenous administered iron in non-anemic iron deficient patients with colorectal cancer.

Primary objectives: The aim is to investigate the effects of intravenously administered iron in non-anemic iron deficient patients on physical capacity, immunological cells and their function prior to surgery.
Primary endpoints: The study will have three separate primary outcomes. The first primary outcome will be changes in cellular respiration (VO2max at the Anaerobic Threshold) measured by the gold standard Cardio Pulmonary Exercise Testing (CPET). The second primary outcome is the preoperative change in the Neutrophil to Lymphocyte Ratio (NLR)30. The third outcome will be difference in up and downregulation of immune function at the invasive front of the tumor, measured by the Nanostring PanCancer Immune profiling panel.