Study of Vitamin D Supplementation Tailored to Vitamin D Deficiency in Breast Cancer Patients

Inclusion Criteria:

• Breast adenocarcinoma treated by neoadjuvant or adjuvant chemotherapy within 12 monthsprior to study enrollment

• WHO performance status 0-1

• Age ≥18 years old

• Affiliation to a social security regime or beneficiary of equivalent social protection

• Written informed consent provided before any study specific procedures Complementary inclusion criterion for randomization

• Proved vitamin D deficiency as defined by serum vitamin D level lower than 30 ng/ml (75nmol/L).

Exclusion Criteria:

• Metastatic disease

• History or presence of any other malignancy (except curatively treated nonmelanomaskin cancer or in situ cervix carcinoma) …………. traités dans les 5 ans précédents.

• Contraindication to calcium or cholecalciferol

• Known severe hypersensitivity to vitamin D or to calcium supplementation or to one ofthe excipients.

• Disease and/or medical conditions accompanied by hypercalcaemia and/or hypercalciuria

• Calcium lithiasis and tissue calcification

• Hypervitaminosis D

• Presence of significant comorbidities: i) Uncontrolled endocrine disease ii) Known disorders of calcium phophorus laboratorytesting iii) Proved osteopenia or osteoporosis requiring vitamin D and calciumsupplements

• Concomitant treatment with other experimental products or another vitamin D calciumtreatment

• Pregnancy, breastfeeding or of reproductive potential not using an effectivecontraceptive method

• Legal inability or restricted legal ability. Medical or psychological conditions notallowing proper study completion or informed consent signature