Soy Isoflavones and Breast Cancer Risk Reduction

Study Results

Results available

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Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE2

Total Enrollment

197 participants

Study Classification

INTERVENTIONAL

Study Start Date

2004-04-30

Study Completion Date

2023-05-31

Brief Summary

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Soy consumption has been associated with reduced risk for developing breast cancer. Soy contains isoflavones which are weak estrogens. The roles of soy isoflavones in reducing breast cancer risk are currently unclear. Breast density has been considered as a breast cancer risk marker. We hypothesize that because isoflavones have estrogen-like activities, breast density and possibly bone density will be lower in women on soy-isoflavones.

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Detailed Description

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This is a randomized, double-blind study, with two arms and 100 women in each arm. Premenopausal women will be recruited and randomly allocated to take one of the two different dietary supplements in pills daily for 2 years. The two supplements are soy isoflavones (treatment) and placebo (carbohydrates). Both treatment and placebo pills will contain multi-vitamins and minerals. Multiple blood, urine, and breast fluid samples will be obtained before and during the dietary supplement periods and analyzed for biomarkers of breast cancer risk. At baseline and after the intervention period, breast density and bone density will be assessed by radiologic techniques. The efficacy of the dietary intervention will be determined by comparing mean changes of serum markers for breast cancer risk,dense breast tissue, and bone mineral density over the two year dietary intervention period in the two supplement groups with adjustment for baseline values and individual patient characteristics of interest. We predict that 2 years of soy isoflavone supplement will reduce breast density, which may be explained by individual changes in serum markers of breast cancer risk.

Conditions

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Breast Cancer

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

One group received soy isoflavones (60 mg daidzein, 60 mg gensitein and 16.6 mg glycitein, all as aglycone equivalent) Another group, carbohydrate filler

Primary Study Purpose

TREATMENT

Blinding Strategy

QUADRUPLE

Participants Caregivers Investigators Outcome Assessors

Research pharmacist dispensed study pills according to a pre-generated randomization list and were blinded to all other aspects of the study protocol.

Subjects, research staff, investigators, and statistician all were blinded to treatment assignment.

Study Groups

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1

soy isoflavones

Group Type EXPERIMENTAL

isoflavones

Intervention Type DIETARY_SUPPLEMENT

soy isoflavones: Each tablet contains 246 mg Novasoy, 676 mg calcium, 15 mg riboflavin, and other innert materials to a total weight of 1000 mg. Subject takes two isoflavone tablets plus 1 multi-vitamin per day for five days per week for upto 2 years.

2

carbohydrates (maltodextrin)

Group Type PLACEBO_COMPARATOR

carbohydrate

Intervention Type DIETARY_SUPPLEMENT

carbohydrate: 246 mg maltodextrin, 676 mg calcium, 15 mg riboflavin and other innert ingredients to a total weight of 1000 mg per tablet. subject takes two tablets plus one multivitamin per day for five days per week for upto 2 years.

Interventions

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isoflavones

soy isoflavones: Each tablet contains 246 mg Novasoy, 676 mg calcium, 15 mg riboflavin, and other innert materials to a total weight of 1000 mg. Subject takes two isoflavone tablets plus 1 multi-vitamin per day for five days per week for upto 2 years.

Intervention Type DIETARY_SUPPLEMENT

carbohydrate

carbohydrate: 246 mg maltodextrin, 676 mg calcium, 15 mg riboflavin and other innert ingredients to a total weight of 1000 mg per tablet. subject takes two tablets plus one multivitamin per day for five days per week for upto 2 years.

Intervention Type DIETARY_SUPPLEMENT

Other Intervention Names

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Isoflavone pill Sugar pill

Eligibility Criteria

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Inclusion Criteria

* healthy premenopausal women
* 30 to 42 years old
* normal mammograms
* regular menstrual cycles

Exclusion Criteria

* abnormal mammograms
* first degree relatives with breast cancer
* pregnant or lactating
* peri- or post-menopause
* breast augmentation, reduction or lifting
* on oral contraceptive medications or exogenous hormones
* medically prescribed diets
* allergic reaction to soy products

Minimum Eligible Age

30 Years

Maximum Eligible Age

42 Years

Eligible Sex

FEMALE

Accepts Healthy Volunteers

Yes