Vitamin D and Mammographic Breast Density
Condition: Breast Cancer
MeSH terms: Breast Neoplasms
Study type: Interventional

Summary: 
      There is some evidence that vitamin D could be used to reduce breast cancer risk. Randomized
      controlled trials would provide definitive evidence about this effect. However, trials with
      breast cancer as outcome are expensive and time-consuming. Use of surrogate outcomes has been
      advocated to accelerate progress in the identification of interventions that could prevent
      breast cancer. Mammographic breast density is one of the strongest breast cancer risk
      indicators and is already used as a surrogate outcome in several breast cancer prevention
      trials. The aim of this double-blind randomized controlled trial is to determine whether
      daily oral supplementation with vitamin D3 (1,000, 2,000 or 3,000 IU) over a period of 1 year
      reduces breast density in premenopausal women compared to placebo. A total of 376 women (94
      per arm) who live in Quebec City will be recruited. Showing that vitamin D reduces breast
      density would provide strong support for the idea that vitamin D can be a safe and
      inexpensive approach for the prevention of breast cancer.
    

Detailed description: 
      OBJECTIVES

      Primary:

      - to determine whether adding oral supplementation with vitamin D3 (cholecalciferol) at doses
      of 1,000, 2,000 and 3,000 IU/d to baseline total vitamin D intake over a period of 12 months
      reduces mammographic breast density among premenopausal women at moderate to high risk of
      breast cancer who reside in the Quebec City area, Canada.

      Secondary:

        -  to assess the net increase in 25(OH)D levels resulting from this vitamin D3
           supplementation;

        -  to document the compliance with, and safety of, supplementation with tested doses of
           vitamin D3 over one year.

      OUTLINE This study is a double-blind, placebo-controlled, randomized trial among
      premenopausal women who live in the Quebec City area and have ≥ 20% breast density at
      baseline.

      The intervention consists of the addition, over baseline total vitamin D intake from food and
      supplements, of three different doses of vitamin D3 (1000, 2000 or 3000 IU/day) for a period
      of 12 months. There are four arms in the trial:

        -  Arm 1: 1,000 IU vitamin D3/d (1 tablet vitamin D 1000 IU + 2 tablets placebo);

        -  Arm 2: 2,000 IU vitamin D3/d (2 tablets vitamin D 1000 IU + 1 tablet placebo);

        -  Arm 3: 3,000 IU vitamin D3/d (3 tablets vitamin D 1000 IU);

        -  Arm 4: placebo (3 tablets placebo/d).

      Vitamin D tablets (1000 IU tablets) and the placebo tablets are undistinguishable in size,
      shape, color and taste, and are manufactured by the same company.
    

Intervention name(s): Vitamin D3; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Given orally
Other intervention name(s): Cholecalciferol
Intervention MeSH terms: Vitamin D; Cholecalciferol
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: breast cancer; mammographic breast density; vitamin D; prevention; randomized controlled trial