This study will evaluate serum vitamin D (25(OH)D) and serum leptin levels at the time of diagnosis of ovarian, primary peritoneal, and/or fallopian tube cancer as well as vitamin D receptor mutation status (FokI SNP genotype). The study will evaluate the impact of vitamin D repletion on serum vitamin D levels, serum leptin levels, and treatment-related morbidity in these patients.

This study will contain 2 cohorts: those with normal serum 25(OH)D and those with low serum 25(OH)D at enrollment. The study will take place in women with ovarian, primary peritoneal, and fallopian tube cancer.

Patients who have given written consent to enroll in the study will have a serum 25(OH)D levels, serum leptin levels, and vitamin D receptor FokI single nucleotide polymorphism analyzed at the time of diagnosis. Patients with vitamin D deficiency will be prescribed vitamin D supplementation according to current guidelines. Treatment with cholecalciferol will not impact cancer therapy. Participants treatment course information will be collected prospectively, but will not be dictated by this study. Serum 25(OH)D and leptin levels will be collected again at the completion of primary therapy, 6 months after the completion of primary therapy, and at the time of disease recurrence. If patients remain vitamin D deficient at any of these follow-up time points, they will be referred to an endocrinologist for further work-up and treatment of their vitamin D deficiency. Data collection will continue for up to 1 year after enrollment.

Inclusion Criteria:

• Patients must have a histologic diagnosis of ovarian, fallopian tube, or primary peritoneal carcinoma per pre-treatment biopsies by laparoscopy, or interventional radiology, paracentesis, or CT guided core biopsy. Histologic documentation of the original primary tumor is required via the pathology report.
• Patients must have adequate: Renal function: Glomerular Filtration Rate (GFR) > 30; Gastrointestinal absorption: No underlying malabsorption syndrome (i.e. inflammatory bowel disease, celiac disease)
• Ability to tolerate oral medication
• Patients taking vitamin D at the time of enrollment without a diagnosis of vitamin D deficiency
• Patients of childbearing potential must have a negative pregnancy test prior to the study entry and be practicing an effective form of contraception.
• If applicable, patients must discontinue breastfeeding prior to study entry.
• Patients must be at least 18 years old

Exclusion Criteria:

• Patients with a known pre-existing diagnosis of vitamin D deficiency.
• Patients with renal disease and a GFR <30
• Patients with primary hyperparathyroidism
• Patients with other invasive malignancies, with the exception of nonmelanoma skin cancer.
• Patients with concomitant endometrial cancer diagnosed at the time of their ovarian cancer are allowed to participate if the endometrial cancer is International Federation of Gynecology and Obstetrics stage 1B or less.
• Patients of childbearing potential, not practicing adequate contraception, patients who are pregnant, or patients who are breastfeeding are not eligible for this trial.