Vitamin D for Women at Increased Risk of Developing Ovarian, Fallopian, or Primary Peritoneal Cancer

Inclusion Criteria: * Patients must be undergoing prophylactic or therapeutic oophorectomy * Patients must be considered to be at a high risk of developing ovarian, fallopian or primary peritoneal cancer, according to 1 or more of the following characteristics: * Patients with a BRCA mutation including variants of uncertain significance * Patients with Lynch syndrome * Patients with a family history that places them at high risk of developing ovarian cancer * Patients with a personal history of breast cancer * Patients currently taking Vitamin D prior to registration will be eligible if serum Vitamin D levels are \<60ng/ml. We believe that most of these patients will be on low replacement doses of Vitamin D3 to begin with but in order to prevent against toxicity their Vitamin D3 levels will be checked at the start of the trial. * Patients must be women age 18 and older * Patients who are of childbearing potential and sexually active must use contraception while on study. * Patients must have a signed and witnessed informed consent and authorization permitting release of personal health information prior to registration on the study. Exclusion Criteria: * Patients who are unable to take Vitamin D3 supplementation are NOT eligible * Patients who are unwilling or unable to undergo oophorectomy are NOT eligible * Patients with suspicious or abnormal findings on preoperative physical exam, laboratory results, or imaging studies within 4 weeks of treatment start are NOT eligible * Patients with a GFR \<59 within 4 weeks of treatment start are NOT eligible * Patients are NOT eligible if they exhibit any contraindications within 4 weeks of treatment start to 25 (OH) D supplement including: * Hypercalcemia (\>11.5mg/dL) * Hypervitaminosis D * Malabsorption syndrome * Active gallbladder disease * Active hepatic disease * Hypoparathyroidism * Leukemia * Nephrolithiasis * Renal failure sarcoidosis * Renal disease (eGFR\<59 ml/min/1.73m2) * Patients currently receiving digoxin are NOT eligible * Patients who are pregnant or breastfeeding are NOT eligible. Patients must have a negative urine pregnancy test at baseline (within 4 weeks of treatment start) to confirm eligibility