Association between Changes in Serum 25-Hydroxyvitamin D Levels and Survival in Patients with Breast Cancer Receiving Neoadjuvant Chemotherapy.

Purpose: We investigated the changes in serum 25-hydroxyvitamin D (25[OH]D) levels before and after neoadjuvant chemotherapy (NCT) and the associations with pathologic complete response (pCR) and survival in patients with breast cancer.

Methods: Serum 25(OH)D concentrations were measured pre- and post-NCT in 374 patients between 2010 and 2013. Based on a cutoff of 20 ng/mL, patients were categorized into "either sufficient" or "both deficient" groups.