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Vitamin D deficiency may increase breast cancer risk in postmenopausal women
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Postmenopausal women with recently diagnosed breast cancer had a higher risk for developing vitamin D deficiency vs. similar women without the disease, with obesity influencing vitamin D status, according to findings published in Menopause.
“The effects of the active [vitamin D] metabolite (1,25(OH)2D3) on the breast are mediated by [vitamin D receptor], which controls the expression of genes that regulate cell proliferation, differentiation and apoptosis,” Murilo Renato Matos Machado, MD, from the department of gynecology and obstetrics at Botucatu Medical School of Sao Paulo State University, and colleagues wrote in the study background. “[Vitamin D] may reduce cancer risk by inhibiting cell proliferation, inducing differentiation and apoptosis, and inhibiting angiogenesis both in the normal and malignant breast. Several uncontrolled studies have reported a high rate of [vitamin D] deficiency in women with breast cancer.”
In a cross-sectional study, Machado and colleagues analyzed data from 209 postmenopausal women with newly diagnosed breast cancer seeking medical care at the Breast Disease Assessment Center in southeastern Brazil from 2015 to 2016 (mean age, 61 years; mean time since menopause, 12.4 years; mean BMI, 30.7 kg/m²). Researchers matched women 1:2 with healthy women by age and menopausal status (n = 418; mean age, 60 years; mean time since menopause, 12.2 years; mean BMI, 28.8 kg/m²). No participants reported taking vitamin D supplementation. Serum 25-hydroxyvitamin D was measured in all women with breast cancer within 10 to 20 days after diagnosis and before proposed treatment. Serum levels of at least 30 ng/mL were defined as sufficient. Researchers used binary logistic regression analysis to examine the association between vitamin D status and breast cancer incidence.
Within the cohort, researchers observed a higher rate of obesity among women with breast cancer vs. controls (57.4% vs. 40.2%). Additionally, researchers observed higher rates of vitamin D insufficiency among women with breast cancer vs. healthy controls (55.6% vs. 49.3%; P = .039) as well as higher rates of vitamin D deficiency (26.2% vs. 20.3%; P = .018).
In risk analyses adjusted for age, time since menopause and BMI, women with breast cancer had a 1.5-fold higher risk for developing vitamin D deficiency vs. healthy women without breast cancer (OR = 1.52; 95% CI, 1.04-2.22).
“Insufficient or deficient 25-(OH)D concentrations were detected in 81.8% of women with breast cancer and in 69.6% of women without cancer,” the researchers wrote. “These results are in agreement with previous studies that demonstrated a high rate of [vitamin D] deficiency among women with breast cancer.”
The mechanisms underlying any effect of vitamin D on breast cancer incidence remain unclear, they wrote.
“The active form of [vitamin D] (1,25(OH)2D) and its derivatives may exert antitumor effects through negative regulation of growth factor signaling, in addition to its effects on proliferation, differentiation, apoptosis and angiogenesis,” the researchers wrote, noting that the regulation of apoptosis in adipocytes and breast cancer cells by 1,25(OH)2D3 “might be the connection between obesity and breast cancer.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.
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