Randomized Double-Blind Placebo-Controlled Biomarker Modulation Study of Vitamin D in Premenopausal Women at High Risk for Breast Cancer (SWOG S0812)
Mené aux Etats-Unis sur 208 femmes présentant un risque élevé de cancer du sein avant la ménopause (âge médian : 44,6 ans), cet essai randomisé multicentrique évalue l'effet, sur la densité mammaire, d'une supplémentation en vitamine D dispensée pendant 12 mois
Résumé en anglais
Observational studies have reported an inverse association between vitamin D intake and breast cancer risk. We examined whether vitamin D supplementation in high-risk premenopausal women reduces mammographic density (MD), an established breast cancer risk factor. We conducted a multicenter randomized double-blind placebo-controlled trial in premenopausal women at high risk for breast cancer (5-year risk>=1.67%, lifetime risk>=20%, lobular carcinoma in situ, prior stage 0-II breast cancer, hereditary breast cancer syndrome, or high MD [heterogeneously/extremely dense]), with a baseline serum 25-hydroxyvitamin D [25(OH)D]<=32 ng/mL. Participants were randomized to 12 months of vitamin D3 20,000IU/week or matching placebo. The primary endpoint was change in MD from baseline to 12 months using the Cumulus technique. Secondary endpoints included serial blood biomarkers (25(OH)D, 1,25(OH)D, insulin-like growth factor (IGF)-1, IGF binding protein-3) and MD change at 24 months. Among 208 women randomized, median age was 44.6 years, 84% were white, 33% had baseline 25(OH)D<20 ng/mL, and 78% had high baseline MD. Comparing the active and placebo groups at 12 months, MD changes were small and did not significantly differ. Mean MD changes at 12 and 24 months were -0.3% and -1.2%, respectively, in the active arm and +1.5% and +1.6% with placebo (p>0.05). We observed a mean change in serum 25(OH)D of +18.9 vs. +2.8 ng/mL (p<.01) and IGF-1 of -9.8 vs. -1.8 ng/mL (p=0.28), respectively. At 12 months, MD was positively correlated with serum IGF-1 and IGF-1/IGFBP-3 (p<0.01). This trial does not support the use of vitamin D supplementation for breast cancer risk reduction.
