128900-144

Prognostic associations of 25OH vitamin D in NCIC CTG MA.21, a phase III adjuvant RCT of three chemotherapy regimens (EC/T, CEF, AC/T) in high-risk breast cancer (BC).

Subcategory: 
ER+
Category: 
Breast Cancer - HER2/ER
Session Type and Session Title: 
Oral Abstract Session, Breast Cancer - HER2/ER
Abstract Number: 
504
Citation: 
J Clin Oncol 32:5s, 2014 (suppl; abstr 504)
Author(s): 
Ana Elisa Lohmann, Judy-Anne W. Chapman, Margot J. Burnell, Mark Norman Levine, Elena Tsvetkova, Kathleen I. Pritchard, Karen A. Gelmon, Patti O'Brien, Lei Han, Hope S. Rugo, Kathy S. Albain, Edith A. Perez, Theodore A. Vandenberg, Haji I. Chalchal, Ravinder Pal Singh Sawhney, Lois E. Shepherd, Pamela Jean Goodwin; Mount Sinai Hospital / University of Toronto, Toronto, ON, Canada; NCIC Clinical Trials Group, Queen's University, Kingston, ON, Canada; Saint John Regional Hospital, Saint John, NB, Canada; Ontario Clinical Oncology Group, McMaster University, Hamilton, ON, Canada; University of Ottawa, Ottwa, ON, Canada; Sunnybrook Odette Cancer Centre and the University of Toronto, Toronto, ON, Canada; British Columbia Cancer Agency, Vancouver, BC, Canada; NCIC, Kingson, ON, Canada; University of California San Francisco Comprehensive Cancer Center, San Francisco, CA; Loyola University Medical Center, Maywood, IL; Mayo Clinic, Jacksonville, FL; London Regional Cancer Program, London, ON, Canada; Allan Blair Cancer Center, Regina, SK, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada

Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).

Abstract Disclosures

Abstract: 

Background: Low vitamin D (VitD) has been associated with poor outcomes in BC. We examined in MA.21 the association of VitD blood levels with relapse-free-survival (RFS) in all patients, and in BC subtypes. Methods: Fasting blood was collected pre-chemotherapy in 935/2,104 ((44.4%) of subjects (blood collection was initiated part-way through the trial); serum was frozen at -80C and shipped on dry ice to Mount Sinai Hospital (Toronto); it was analyzed for Vit D (radioimmunoassay, Diasorin) 25(OH)D (nmol/L). VitD underwent a λ=0.5 Box-Cox transformation for analysis to reduce asymmetry; data were back-transformed for reporting. VitD was assessed as a transformed continuous factor, and by quartiles and IOM categories (<40, [40-50), [50-125), >125 nmol/L). Univariate and multivariate (mv) assessments were with Cox models, adjusted for treatment, stratification factors, and imbalances in who had VitD assessed. Results: Median age was 47.8 years; most patients were white (91.6%), premenopausal (69.4%) with good performance status (PS) 0-1 (99.9%). The majority presented with grade III (52%), HER2 neg (66.6%), HER2 missing (22.9%), ER pos (61.9%), T1-2 (89.4%), N+ (72.7%) BC. 52.1% underwent mastectomy and 74.3% received adjuvant radiotherapy. Compared to the full MA.21 population, those with VitD levels were marginally (but significantly) more likely to be white, PS 1 or 2, to have undergone mastectomy and to have ER+, HER2 neg tumors. Mean Vit D was 69.7 nmol/L [95% CI (68.1-71.3)] nmol/L. The majority (752/935 = 80.5%) had levels > 50nmol/L (20ng/ml), considered adequate by the Institute of Medicine (IOM). In adjusted mv analyses, (continuous) VitD was not associated with RFS (HR 0.98, 95% CI (0.93-1.03); p=0.36) or categorical variable (between quartiles, p=0.20-0.43; between IOM categories, p=0.33-0.78). There were no significant differences in mean VitD levels or association of VitD with RFS in tumor subtypes (ER+, HER2- / any ER, HER2+ / ER-, HER2-; p=0.14-0.50). Conclusions: There is no evidence that VitD was associated with RFS in MA.21; the majority of subjects had adequate VitD levels at study entry. Clinical trial information: NCT00014222.