Calcium Plus Vitamin D Supplementation and the Risk of Breast Cancer
Year: 2008
Type: article
Abstract: BACKGROUND: Although some observational studies have associated higher calcium intake and especially higher vitamin D intake and 25-hydroxyvitamin D levels with lower breast cancer risk, no randomized trial has evaluated these relationships. METHODS: Postmenopausal women (N = 36 282) who were enrolled in a Women's Health Initiative clinical trial were randomly assigned to 1000 mg of elemental calcium with 400 IU of vitamin D(3) daily or placebo for a mean of 7.0 years to determine the effects of supplement use on incidence of hip fracture. Mammograms and breast exams were serially conducted. Invasive breast cancer was a secondary outcome. Baseline serum 25-hydroxyvitamin D levels were assessed in a nested case-control study of 1067 case patients and 1067 control subjects. A Cox proportional hazards model was used to estimate the risk of breast cancer associated with random assignment to calcium with vitamin D(3). Associations between 25-hydroxyvitamin D serum levels and total vitamin D intake, body mass index (BMI), recreational physical activity, and breast cancer risks were evaluated using logistic regression models. Statistical tests were two-sided. RESULTS: Invasive breast cancer incidence was similar in the two groups (528 supplement vs 546 placebo; hazard ratio = 0.96; 95% confidence interval = 0.85 to 1.09). In the nested case-control study, no effect of supplement group assignment on breast cancer risk was seen. Baseline 25-hydroxyvitamin D levels were modestly correlated with total vitamin D intake (diet and supplements) (r = 0.19, P < .001) and were higher among women with lower BMI and higher recreational physical activity (both P < .001). Baseline 25-hydroxyvitamin D levels were not associated with breast cancer risk in analyses that were adjusted for BMI and physical activity (P(trend) = .20). CONCLUSIONS: Calcium and vitamin D supplementation did not reduce invasive breast cancer incidence in postmenopausal women. In addition, 25-hydroxyvitamin D levels were not associated with subsequent breast cancer risk. These findings do not support a relationship between total vitamin D intake and 25-hydroxyvitamin D levels with breast cancer risk.
DOI: 10.1093/jnci/djn360
Authors: Rowan T. Chlebowski, Karen C. Johnson, Charles Kooperberg, Mary Pettinger, Jean Wactawski-Wende, Tom Rohan, Jacques Rossouw, Dorothy Lane, Mary Jo O’Sullivan, Shagufta Yasmeen, Robert A. Hiatt, James M. Shikany, Mara Vitolins, Janu Khandekar, F. Allan Hubbell, for the Women's Health Initiative Investigators
Institutions: University of California, Los Angeles, The Lundquist Institute, Harbor–UCLA Medical Center, University of Tennessee Health Science Center, Fred Hutch Cancer Center, University at Buffalo, State University of New York, Yeshiva University, National Institutes of Health, Stony Brook University, University of Miami, University of California, Davis, University of California, San Francisco, University of Alabama at Birmingham, Wake Forest University, Northwestern University, University of California, Irvine
Language: English
Topic: Vitamin D Research Studies
Subfield: Pathology and Forensic Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2162139093