Change of serum vitamin D according to the breast cancer treatment.

172 Background: Vitamin D deficiency is associated with increased breast cancer risk and decreased breast cancer survival. The purpose of this study was to determine the effect of breast cancer adjuvant treatment to the vitamin D status, as measured by the serum hydroxyvitamin D (25OHD) in breast cancer patients. Methods: For 589 patients who was diagnosed as a non metastatic breast cancer in 2009 at the asan medical center, blood was prospectively analyzed in batches for serum 25 OHD level at basal and at 6 and 12month. We excluded the patients who took a vitamin D supplementation and got a neoadjuvant chemotherapy. Vitamin D sufficiency was defined as serum as 30ng/ml or greater, insufficiency as 20 to 29 ng/ml and insufficiency as less than 20ng/ml. Results: At baseline, mean serum 25OHD was greater in summer (April to Oct) than Winter (Nov to May ) (28.2ng/ml vs 32.9ng/ml respectively, p=0.000). The patients who did not get a chemotherapy and anti-hormonal therapy as baseline, the patient with chemotherapy showed decreased serum 25OHD level than who without chemotherapy in 6 month but not in 12 month (p=0.003, vs p=0.156 respectively). The patients who had taken anti-hormonal therapy showed significant increasing serum 25OHD in 6 month and 12 months (p=0.000 both). For the patients who got both chemotherapy and anti-hormonal therapy, the changes of serum 25OHD level is smaller than the patients who got a chemotherapy only. For the patients who got a chemotherapy, 57% of patients were vitamin D sufficient at baseline, but 27% of patients in 6 month and 49% in 12 month (p=0.001). Conclusions: Vitamin D status was worse during chemotherapy but recovered after chemotherapy. Antihormonal therapy make the serum vitamin D level increased. The translational research about the effect of chemotherapy and antihormonal therapy to the vitamin D status should be warranted.