Potential Benefits of Soy Food Consumption for Breast Cancer Survivors
Posted Mar 21 2011 10:25am
Soy food and soy isoflavone consumption by breast cancer patients remains an area of controversy and debate among the medical community. This controversy stems from the fact that the soy isoflavones found naturally in soybeans are structurally similar to estrogen and can act like a weak estrogen in some cases. This has caused many individuals to become concerned about the effect of soy food and soy isoflavone consumption on estrogen-dependent diseases like estrogen-receptor positive breast cancer.
However, recent breast cancer research over the last couple of years suggests that soy foods and soy isoflavones have breast cancer fighting benefits including possibly reducing breast cancer risk and reducing the risk of breast cancer recurrence. Two of the largest and most recent population-based studies, the Shanghai Breast Cancer Survival Study (free to download) and the Life After Cancer Epidemiology study, reported that higher levels of soy food and soy isoflavone consumption in breast cancer survivors was linked to reduced risk of breast cancer recurrence and reduced risk of death. Nonetheless, additional studies in different populations are needed to further clarify the potential benefits of soy consumption for breast cancer survivors.
A new breast cancer study published online in Cancer Epidemiology, Biomarkers & Prevention explored the relationship between soy food and soy isoflavone consumption on mortality in breast cancer patients who had been diagnosed with breast cancer within the previous 2 years on average. For this study, soy food and soy isoflavone consumption were determined in nearly 3,100 breast cancer survivors using a food-frequency questionnaire and a separate questionnaire to assess soy supplement intake. Breast cancer survivors reported new breast cancer events every 6 months, which were then confirmed with medical records. Analysis of the link between breast cancer recurrence, mortality and soy consumption during 7 years of follow up showed that
The risk of death was significantly decreased as soy isoflavone intake increased.
Breast cancer survivors consuming more than 16.3 mg of soy isoflavones per day had a 54% reduced risk of dying.
Soy food and soy isoflavone intake was not linked to breast cancer recurrence regardless of whether the breast cancer survivors were taking tamoxifen or not.
When examined by hormone receptor status of the breast cancer tumor, soy consumption did not increase mortality or breast cancer recurrence in hormone receptor-positive or hormone receptor-negative breast cancer survivors.
These are interesting results that confirm the results of the other two large population-based studies published in the last couple of years. This study and the previous two studies reported that soy food or soy isoflavone consumption reduced the risk of dying and either had no effect on or reduced the risk of breast cancer recurrence. Additionally these studies suggested that the potential benefits of soy consumption for breast cancer survivors is not altered by tamoxifen use, something that has been a concern among the medical community. This new breast cancer study also suggests that soy consumption has no impact on breast cancer recurrence or mortality in breast cancer survivors diagnosed with hormone receptor-positive breast cancer. Overall, these three recent studies suggest that breast cancer survivors should be able to enjoy adding soy foods to their diet if they desire.