Effects of pre-surgical Vitamin D supplementation and ketogenic diet in a patient with recurrent breast cancer

Background: A woman, mother of one at the age of 19 years, was diagnosed with mammary adenocarcinoma in the right breast in 1985 at the age of 37 years. The patient underwent surgery (quadrantectomy), lymphadenectomy and radiotherapy. In 1999, an adenocarcinoma was diagnosed in the left breast, followed by adequate resection, radiotherapy and anti-oestrogen receptor treatment for 6 years. In March 2014, an infiltrating adenocarcinoma was diagnosed in the remaining part of the right breast that had been operated on and irradiated in 1985. Case Report: The pre-surgical biopsy, showed weak positivity for progesterone receptor (PgR) (10%, score 2+), and high positivity for the nuclear protein Ki67 (30%). In the three weeks between diagnosis and operation, when no other treatment had been planned, the patient decided to self-administer high doses of oral vitamin D3 (10,000 IU/day), and to follow a strict ketogenic diet. Results: Following right mastectomy, analysis of the surgical specimen showed no positivity for HER2 expression (negative, score 0), and significant increase in positivity of PgR (20%). Positivity for ER and Ki67 were unaltered. Conclusion: This observation indicates that a combination of high-dose vitamin D3 and ketogenic diet leads to changes in some biological markers of breast cancer, i.e. negativization of HER2 expression and increased expression of PgR.