Abstract P5-13-09: Feasibility of a Randomized Controlled Trial of Vitamin D vs. Placebo in Recently Diagnosed Breast Cancer Patients
Authors: Cescon DW , Ganz PA , Hallak S , Ennis M , Mills BK , Goodwin PJ. 
Published: April 2011

Background: Vitamin D (Vit D) supplementation is an area of interest in the primary and secondary prevention of many cancers. We previously reported a high prevalence of Vit D insufficiency and deficiency in newly diagnosed breast cancer (BC) patients. Low Vit D levels were associated with poor BC outcomes. Here we evaluate the state of Vit D adequacy and supplementation in a more recently diagnosed cohort of BC patients from 2 large urban centres, and we examine the feasibility of a placebo-controlled randomized trial (RCT) of supplementation in this population. Patients and Methods: Women diagnosed with T1-3, N0-3, M0 invasive BC within the previous 2 years were prospectively identified from institutional registries and recruited from Mount Sinai Hospital, Toronto and UCLA, Los Angeles (LA), between March 2009 and January 2010. Anthropometric measurements were performed, and dietary, lifestyle and medication histories were obtained using structured questionnaires and interviews. Tumor and treatment characteristics were obtained from clinical records; blood samples were collected for analysis of Vit D levels. The pre-specified feasibility criteria for a Vit D (vs placebo) RCT were: ≥30% of patients with (i) deficient or insufficient Vit D levels, (ii) taking ≥1000 IU Vit D/day and (iii) willing to participate in such a trial.

Results: 173 eligible patients were enrolled (80 Toronto, 93 LA). Median age at enrollment was 57 years; 73.4% were post-menopausal. Median tumor size (1.8 cm), lymph node involvement (39%), ER (80%), PR (65%) and Her2 (15%) positivity were similar between centres. Treatment characteristics including rates of mastectomy (44%), adjuvant chemotherapy (56%), radiation (68%), hormonal therapy (69%) and trastuzumab (14%) did not differ between centres. 84.4% of women reported use of Vit D containing supplements, with median daily doses of 1200 IU (Toronto) and 1400 IU (LA) (p=0.3) among users. Respective median 25-OH Vit D levels were 85.5 nmol/L (34.3 ng/mL) and 98.5 nmol/L (39.5 ng/mL) (p=0.04), and rates of deficiency, insufficiency and adequacy were 3.8%, 23.8%, 72.5% (Toronto) and 4.3%, 20.7%, 75.0% (LA) (p=0.88). No Vit D levels were in the toxic range. 25-OH Vit D levels correlated with Vit D supplement use (r=0.41, P&lt;0.0001). 68% of women expressed willingness to participate in a Vit D RCT; however, only 12.7% of the study population met the pre-specified feasibility criteria.

Conclusions: Vit D levels and supplementation rates are substantially higher in these BC patients than in previous cohorts, though more than 25% of women do not have adequate levels. Rates of adequacy did not

differ between patients recruited in Toronto and LA. While the maj ority of women would be willing to participate in an RCT of Vit D supplementation, low levels of deficiency/insufficiency and high rates of supplement use may limit the feasibility of such a study. Funded by the Breast Cancer Research Foundation.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-13-09.