Patient Summary: The Women's Health Initiative randomized trial of calcium plus vitamin D: Effects on breast cancer and arthralgias

Carolyn Vachani, RN, MSN, AOCN
Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 9 de junio del 2006

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The Women's Health Initiative randomized trial of calcium plus vitamin D: Effects on breast cancer and arthralgias.

This study looked at the question: would calcium and vitamin D supplements decrease risk of breast cancer ? 32,282 women were randomized to receive either 1000 mg calcium carbonate and 400 IU vitamin D or placebo. The women were postmenopausal, with no history of breast cancer for the past 10 years. The study was stopped after 7 years.

The study found no difference in the rates of invasive breast cancer (528 cases in Calcium/D group vs. 546 cases in the placebo group) or non-invasive breast cancer. They also reported no difference in joint pains, which was a secondary question of the study.

Several previous retrospective studies (looking back on Ca/Vit D use) did show a benefit. Possible explanations for the lack of effect on breast cancer incidence in this study include:

    • Too much baseline Vit D use (participants were allowed to have used ~750 IU prior to the study) compared with level of intervention (400 IU) to see an effect from intervention
    • Not enough Vit D intervention? Need about 3000 IU to achieve serum level of 42 ng/mL, which has been correlated with greatest breast cancer risk decrease
    • Too much baseline Ca use before randomization (mean intake was 1165 mg, which is close to optimal amount, 1200 mg)
    • Participation in hormone therapy trial may have confounded effect (this study was part of the WHI hormone trial)
    • Intervention in the right age group?

At the present time, Ca and Vit D supplementation can not be recommended to prevent breast cancer.



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