Iron deficiency has been reported in up to 35% of patients with a gynecologic malignancy. These patients often require surgical intervention to determine the stage and to treat their illness. Blood transfusions occur in approximately 14% of these surgeries and carry immediate and long-term risks, including surgical site infection, cancer recurrence, and increased surgical length of stay. Intravenous iron formulations have the potential to rapidly correct anemia in patients with gynecologic malignancy and potentially decrease blood transfusion and complications following surgery. This prospective, randomized, placebo-controlled, double blind study aims to assess the effectiveness of preoperative ferric derisomaltose/iron isomaltoside compared to placebo in correcting preoperative hemoglobin in patients undergoing surgery for gynecologic malignancy. The primary outcome is to assess the effectiveness of this formulation on pre-operative hemoglobin, and the feasibility of a larger, outcomes based, study in the future. Exploratory outcomes are to assess the effect of preoperative intravenous iron on surgical length of stay, complications, and patient-reported quality of life.

Inclusion Criteria:

1. At least 18 years of age and signed written informed consent

2. Patients undergoing elective major surgery on the gynecologic oncology service with the following criteria will be considered for inclusion:

   1. The indication for the operation may be for suspected or proven gynecologic malignancy.
   2. Major surgery is defined as an operation of a duration of 1 hour or greater, with an Aletti complexity score of at least 1[19].
   3. The expected time from recruitment to surgery is at least 28 days.

3. Screening haemoglobin less than 120g/L and transferrin saturation (TSAT) <20%

4. Randomization and administration of study infusion a minimum of 21 days and maximum 90 days before planned operation.

5. Negative pregnancy test for women of childbearing potential (within last 7 days), and agree to use effective form of contraception until 6 weeks post treatment (if applicable)

6. Laboratory data used for determination of eligibility at the baseline visit must not be older than 4 weeks.

Exclusion Criteria:

1. Known history of acquired iron overload, or family history of haemochromatosis or thalassemia, or TSAT >50%
2. Known alternative cause for anemia (e.g. B12 or folate deficiency, or haemoglobinopathy)
3. Known hypersensitivity to FDI or its excipients
4. Temperature >38 C or patient on non-prophylactic antibiotics
5. Known chronic liver disease or active hepatitis
6. Received erythropoietin or IV iron therapy in previous 12 weeks
7. If LFT's are ordered, either clinically indicated or for chemotherapy, and screening alanine transaminase (ALT) or aspartate transaminase (AST) is above three times the upper limit of normal (ULN) range
8. Immunosuppressive therapy (for solid organ transplant), or renal dialysis (current, or planned within next 12 months)
9. Unfit for elective surgery
10. Pregnancy or lactation
11. Unable to fully comprehend and/or perform study procedures
12. Cervical cancer with a clinical stage of 2A or greater.

Intravenous treatment will be prepared by an unblinded provider and placed in opaque bags/tubing to blind the patient, administrator of the medication, and subsequent outcome assessors and care providers.