Higher versus Lower 25-hydroxyvitamin D Levels Markedly Reduce Breast Cancer Risk

by | Nov 19, 2019 | 2018, Breast Cancer, Cancer, Vitamin D - Cancer

Written by Joyce Smith, BS. Pooled analysis of three studies show that the relationship between 25(OH)D serum levels and breast cancer risk are inversely related.

cancer - breastNumerous studies have shown an association between 25-hydroxyvitamin D [25(OH)D] status and risk of breast cancer 1. However, there are few studies that look at concentrations of 25(OH)D in excess of 100 nmol/l and breast cancer risk 2,3. This study pooled the results of two randomized controlled trials (RCTs) to investigate the relationship between 25(OH)D levels and breast cancer incidence.

The first RCT, published in 2007 by Lappe et al 4, focused on bone health and cancer, and involved 1,129 healthy, postmenopausal women, aged 55 or older from eastern Nebraska. They were allocated to three groups who supplemented daily with 1,100 IU of vitamin D3 and 1,400-1,500 mg calcium; calcium only; or placebo only. A four-year follow-up revealed that the vitamin D3 and calcium group had a 77% reduced risk of cancer compared to the placebo group.

The second RCT by Lappe et al in 2017 5 focused strictly on cancer, and involved 2,196 women who took either 2000 IU of vitamin D3 and 1,500 mg calcium or a placebo daily. A four-year follow-up revealed a 30 % reduction in cancer incidence in the vitamin D3-calcium group compared to placebo group. The third, a prospective cohort study, involved 1,713 women enrolled in the Grassroots Health cohort who were free to choose their daily amount of vitamin D3, were tested frequently for their 25(OH)D levels and understood the importance of achieving and maintaining 25(OH)D blood levels above 40 g/ml (100 nmol/l) for good health. They were followed up for 1.9 years.

The current 2019 6 study by Lappe and team was a final cohort of 5,038 women that pooled the results of both RCTs and the prospective cohort study to investigate the relationship between vitamin D status  and breast cancer incidence across a broad range of 25(OH)D concentrations among women aged 55 years and older. The pooled cohort provided a larger sample size and greater statistical power and allowed for a greater range of 25(OH)D concentrations.

Analysis revealed that women with Vitamin D status of ≥ than 150 nmol/l (≥ 60ng/ml) had an 80% lower risk of breast cancer than women with 25(OH)D concentrations of less than 50nmol/l (<20 ng/ml), after adjusting for age, BMI, smoking status and calcium supplementation.

The findings also show that the risk of breast cancer is dose responsive, with 25(OH)D levels of >150nml/l (≥ 60ng/ml) being the most protective. Testing for vitamin D status and optimizing levels to >150nml/l could be considered as part of a strategy for 25(OH)D breast cancer prevention.

The present study involved a large population thus increasing generalizability and its perspective design enabled the use of vitamin D values before breast cancer diagnosis to distinguish between cause and effect. Breast cancer is the most common non-skin cancer in women 7. Primary prevention and evidence –based interventions are essential to decrease  breast cancer  incidence ( 252,000 new cases projected in 2017)  and the  associated mortality (40,600  projected deaths  in 2017) 7 and economic costs (16.6 billion in 2010) 8 in the united States. The analysis from this study suggests that if women raised their 25(OH) D concentration from a mean of approximately 30 ng/ml 9 to 55 ng/ml, more than 6 billion dollars could be saved every year in the United States. The authors add that Vitamin D status is a modifiable risk factor for breast cancer, and increasing 25(OH)D concentrations via supplementation at the population level is safe and affordable.

Source: McDonnell SL, Baggerly CA, French CB, Baggerly LL, Garland CF, Gorham ED, et al. (2018) Breast cancer risk markedly lower with serum 25- hydroxyvitamin D concentrations 60 vs <20 ng/ ml (150 vs 50 nmol/L): Pooled analysis of two randomized trials and a prospective cohort. PLoS ONE 13(6): e0199265. https://doi.org/10.1371/ journal.pone.0199265

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Posted November 19, 2019.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

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