13P - A Randomized, Double-blind, Placebo-Controlled Window of Opportunity Trial Evaluating Clinical Effects of High Dose Vitamin D in Patients with Brea...

Date 04 May 2017
Event IMPAKT 2017
Session Welcome reception and Poster Walk
Topics Breast Cancer
Presenter Angel Arnaout
Authors A. Arnaout1, C. Addison2, S. Robertson3, G. Pond4, N. Chang3, M. Clemons5
  • 1Surgery, Ottawa Hospital Cancer Center, K1H8L6 - Ottawa/CA
  • 2Cancer Therapeutics, Ottawa Hospital Research Institute, K1H8L6 - Ottawa/CA
  • 3Pathology, Ottawa Hospital, K1H 8L6 - Ottawa/CA
  • 4Ontario Clinical Trials Oncology Group, McMaster University, L8V 1C3 - Hamilton/CA
  • 5Medical Oncology, Ottawa Hospital Cancer Center, K1H8L6 - Ottawa/CA



Background: Epidemiologic and preclinical laboratory data suggest that there is a role for vitamin D in breast cancer therapy through its tumor suppressive effects. The objective of this study was to assess the biologic effects of short term high dose vitamin D intake on breast tumor biology in a window of opportunity presurgical trial.

Methods: This is a prospective, randomized, double blind, placebo-controlled phase 2 trial assessing the effect of high dose (40,000 IU) of oral vitamin D3 on breast cancer biology in patients awaiting surgical management of their primary breast cancer. Eligible patients took the study drug for at least 2 weeks leading up to the day of surgery. Pre- and post- 25-OH vitamin D blood levels, tumor Ki67 index and tumor caspase 3 were analyzed.

Results: 80 patients completed the study; 38 in the control group and 42 in the vitamin D group. The mean duration on the study was 19 days. Within the study cohort, 16/80 (64%) were ER positive, 55/80 (55%) were PR positive, 65/80 (61%) were Her2 negative. Mean overall baseline blood 25-OH Vitamin D levels in the study cohort was 76.4 nmol/L, which increased to 241.9 nmol/L in the vitamin D treated group (p=0.0001). Mean Ki67 level at baseline was 35.4% overall and there was no statistically significant difference in the ki67 obtained from the surgical specimen between the treatment group (mean = 39.3%) and the control group (41.0%). Baseline caspase 3 level was 31.2% overall and there was no statistically significant difference in the caspase 3 obtained from the surgical specimen between the treatment group (mean = 13.1%) and the control group (15.6%). However, the overall caspase 3 level (14%) obtained from the surgical specimen from both study groups was significantly lower than that at obtained from the core biopsy at baseline (31.2%) (p=0.04).

Conclusion: This is the first prospective randomized trial evaluating the effect of short term, high dose vitamin D on the in vivo markers of proliferation and apoptosis. No significant difference was seen in these markers as a result of vitamin D intake, despite significantly higher circulating levels of 25-OH vitamin D in the blood.

Clinical trial identification

ClinicalTrials.gov Identifier: NCT01948128