Vitamin D Supplementation During Neoadjuvant Chemotherapy for Breast Cancer Improves Pathological Complete Response: A Prospective Randomized Clinical Trial

Abstract

Introduction: Achieving a pCR serves as a biomarker indicating enhanced overall survival for breast cancer patients undergoing NST. Vitamin D enhances the antitumor effect of chemotherapeutics as demonstrated in cancer cells and animal models. In this prospective randomized clinical study, we aim to investigate the effect of oral vitamin D supplementation during neoadjuvant systemic therapy (NST) on pathologic complete response (pCR).

Methods: Between June 2019 and June 2023, an oral form of 50,000 IU vitamin D3 (cholecalciferol) replacement was administered once a week during NST for the study group.

Results: There were 114 (50.2%) cases in the study group and 113 (49.8%) in the control group (totally 227 cases). Factors that positively influenced pCR were higher clinical T stage, higher AJCC clinical stage, Estrogen receptor negativity, progesterone receptor negativity, human epidermal growth factor receptor 2 positivity, high Ki-67 expression (≥ 20%), hormone negative molecular subtypes, and vitamin D intake in univariate analysis. In the multivariate analysis, factors significantly affecting pCR were vitamin D intake (OR: 2.33, 95% CI 1.20-4.53; p = 0.013), hormone receptor negativity (OR: 2.22, 95% CI 1.11-4.43; p = 0.024), and Ki-67 ≥ 20% (OR: 3.27, 95% CI 1.03-10.34; p = 0.044).

Conclusions: This is the first and only study to compare the effect of oral vitamin D supplementation on pCR during NST. Vitamin D supplementation during NST has a significant effect on pCR in breast cancer patients. Although this effect is not significant for axillary pCR, there is an almost significant correlation.

Trial registration: ClinicalTrials.gov (Identifier: NCT03986268).

Keywords: ERBB2 protein; breast neoplasms; dietary supplements; human; neoadjuvant systemic therapy; pathologic complete response; vitamin D.