Effect of Vitamin D Supplementation on the Efficacy and Adverse Effects of Neoadjuvant Therapy in Patients with Breast Cancer

This is a parallel-group, open-label randomized controlled trial designed to investigate the effects of supplemental vitamin D (VD) on the outcomes and side effects of neoadjuvant therapy in patients with breast cancer. Both groups will receive standard neoadjuvant therapy on day 1 and for each subsequent cycle. Additionally, vitamin D2 will be randomly administered to both groups.Blood samples and imaging results will be collected and analyzed prior to the initiation of neoadjuvant therapy and after every two cycles. Key outcomes to be recorded include the pathological complete response rate (pCR), objective response rate (ORR), disease control rate (DCR), and grade III or higher adverse effects related to neoadjuvant therapy. The primary and secondary study findings, along with adverse events, will be thoroughly evaluated.