Soy Protein and Breast Cancer Risk Reduction

Phase 2

Completed

Conditions: Breast Cancer

Interventions: Dietary Supplement: soy milk
Dietary Supplement: cow's milk

Registration Number: NCT00204477

Lead Sponsor: The University of Texas Medical Branch, Galveston

Brief Summary: Soy consumption has been associated with reduced risk for developing breast cancer. Ovarian hormones and breast density are considered breast cancer risk markers. We propose to test the hypothesis that consumption of soy protein reduces ovarian steroid hormones and results in a corresponding reduction in breast density comparing to casein protein.

Detailed Description: The aims will be tested by conducting 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 two different dietary supplements daily for 2 years. The two test diets soy protein drink and caseinate protein drink. Multiple blood, urine, and breast fluid samples will be obtained before and during the dietary intervention period and analyzed for ovarian hormones. At baseline and after the intervention period, breast density, and bone density will be assessed by radiological techniques at baseline and 1 yr and 2 yr after protein drink supplementation. The efficacy of the dietary intervention will be determined by comparing mean changes of ovarian steroids, and density of the breast and bone tissues over the 2 year dietary intervention period in the two diet groups with adjustment for baseline values and individual patient characteristics of interest. We predict that 2 years of soya dietary supplements will reduce breast density, which will be explained by individual hormonal changes.

Recruitment & Eligibility

Status: COMPLETED

Sex: Female

Target Recruitment: 321

Inclusion Criteria

healthy premenopausal women
30 to 40 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, and lifting
on oral contraceptive medications or exogenous hormones
medically prescribed diets
allergic reaction to soy or cow's milk

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Soy milk	soy milk	Subjects will consume two soy milk drinks from the content of 2 sachets (40 g isoflavone-free soy protein and 600 mg calcium) in place of a small meal, five days per week. Each sachet will contain 20 g soy protein and 300 mg calcium. Content of sachets will be mixed with \~1.6 liter of water for ingestion.
Cow's milk	cow's milk	Subjects will consume two cow's milk drinks from the content of 2 sachets (40 g cow's milk protein, casein, and 600 mg calcium) in place of a small meal, five days per week. Each sachet will contain 20 g cow's milk protein and 300 mg calcium. Content of sachets will be mixed with \~1.6 liter of water for ingestion. Casein is free of ovarian hormones.

Primary Outcome Measures

Name	Time	Method
Mammographic Density (2 Years)	2 years	Breast images were acquired by digital mammography. Fibroglandular tissue were segmented from fatty breast tissue. The total breast area is the sum of the fibroglandular tissue area and fatty breast tissue area. Mammographic density (breast density) is the percentage of fibroglandular tissue in the total breast.
Percentage of Grandular Tissue in Total Breast Measured by MRI	2 years	Breast images acquired by breast magnetic resonance imaging (MRI). The amount of fatty breast tissue,(cc), glandular breast tissue(cc ), total breast (cc), and percentage of glandular tissue in total breast (%) were estimated.
Mammographic Density (1 Year)	1 Year	Breast images were acquired by digital mammography. Fibroglandular tissue were segmented from fatty breast tissue. The total breast area is the sum of the fibroglandular tissue area and fatty breast tissue area. Mammographic density (breast density) is the percentage of fibroglandular tissue in the total breast.
Breast Tissue Composition Measured by MRI	2 years	Breast images acquired by breast magnetic resonance imaging (MRI). The amount of fatty breast tissue,(cc), glandular breast tissue(cc ), total breast (cc), and percentage of glandular tissue in total breast (%) were estimated.
Mammographic Density (Baseline)	Baseline	Breast images were acquired by digital mammography. Fibroglandular tissue were segmented from fatty breast tissue. The total breast area is the sum of the fibroglandular tissue area and fatty breast tissue area. Mammographic density (breast density) is the percentage of fibroglandular tissue in the total breast.