Soy Isoflavones and Breast Cancer Risk Reduction

The University of Texas System (UT)

Status and phase: Completed; Phase 2

Conditions: Breast Cancer

Treatments: Dietary Supplement: isoflavones; Dietary Supplement: carbohydrate

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT00204490

03-260

1UL1RR029876-01 (U.S. NIH Grant/Contract)

UTMB GCRC #635 (Other Identifier)

R01CA095545 (U.S. NIH Grant/Contract)

M01RR000073 (U.S. NIH Grant/Contract)

Details and patient eligibility

About

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.

Full description

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.

Enrollment: 197 patients

Sex: Female

Ages: 30 to 42 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Quadruple Blind

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197 participants in 2 patient groups, including a placebo group

1

Experimental group

Description:

soy isoflavones

Treatment:

Dietary Supplement: isoflavones

2

Placebo Comparator group

Description:

carbohydrates (maltodextrin)

Treatment:

Dietary Supplement: carbohydrate