Soy-rich diet associated with fewer fractures in breast cancer survivors

Diets high in soy foods are associated with a decreased risk of osteoporotic bone fractures in pre-menopausal breast cancer survivors according to a new study.

Breast cancer is a prevalent disease in women which is associated with a decrease in their bone mineral density.

Going under many treatments for breast cancer can cause premature menopause and decrease bone mineral density. This leads to a higher incidence of osteoporosis-related fractures among survivors compared to healthy women in the same age range.

"The menopausal transition is known to be a period of high risk for bone loss, and given the relative scarcity of data related to fracture risk among younger women with breast cancer, this study marks an important contribution to this body of literature," said the paper's lead author, Evelyn Hsieh.

The study was published in the Journal JNCI Cancer Spectrum.

During the course of the study, researchers studied the impact that BMI, exercise, and soy-rich food consumption had on bone fracture rates among breast cancer survivors.

The study incorporated the data of 5,042 newly diagnosed breast cancer survivors between the ages of 20 and 75. Researchers collected detailed information at enrollment, including cancer diagnosis and treatment history, medication use, dietary habits, exercise and other lifestyle factors.

About 52 per cent of the women in the study were postmenopausal. Patients then had follow-up visits at 18 months, and 3, 5, and 10 years after their diagnosis to update exposure and outcome information.

Throughout the 10-year study period, 3.6 per cent of survivors reported an osteoporotic bone fracture.

But women who had a higher soy intake were associated with a 77% reduced risk of osteoporotic fractures in younger women, and exercise showed a significantly reduced risk of fractures among older women.

Consistent with prior studies, the extended use of tamoxifen, a drug that is prescribed for breast cancer patients showed a 37 per cent reduced risk of fractures in the overall study population.

Tamoxifen is a selective estrogen receptor modulator, or SERM, that causes an increase in bone mineral density. Soy-based foods, which are rich in isoflavones, are a natural alternative for SERM.

"Our findings, in particular regarding the protective effects of soy food consumption provide novel insight into how future interventions can be best tailored to different risk groups," said Evelyn.