Genistein and Breast Cancer Tumors: Should Soy Consumption Be Halted in Breast Cancer Patients?
According to recent scientific findings, the positive or negative effects associated with breast cancer patients consuming soy products can differ according to when the food was consumed. Patients who had already eaten soy products prior to their diagnosis might actually benefit from it, but those who only start eating soy after undergoing tamoxifen treatment could be faced with their cancer returning.
The study is entitled “Lifetime Genistein Intake Increases the Response of Mammary Tumors to Tamoxifen in Rats,” and could help scientists determine the result of the dilemma regarding the advantages and drawbacks of soy consumption in the case of breast cancer patients.
The Role of Genistein in Influencing Breast Cancer
Genistein is a substance found abundantly in soy products that can actually take on the role of activating estrogen receptors because of its estrogen-like structure. Since excess estrogen can lead support the growth of ER-positive breast cancer tumors, medical specialists advise breast cancer patients to avoid soy entirely.
Surprisingly, the high soy consumption associated with certain Asian countries seems to have led to a decline in breast cancer that is five times greater than in the West. The senior investigator of the study and professor of oncology practicing at the Georgetown Lombardi Comprehensive Cancer Center, Leena Hilakivi-Clarke, PhD, considers this to be a key factor in determining how soy really affects the body during and after the development of breast cancer.
The Timing of Genistein and Soy Consumption
The study involved a mouse model that was used to test how genistein intake directly influences breast cancer. Separate groups of mice were used to test genistein-based diets both during adulthood and right after birth. While the latter was used as a control that mimicked the effects of a soy-rich oriental diet, the former group involved mice that were only given genistein after they were treated with tamoxifen to treat their mammary tumors.
The findings were conclusive, showing that a genistein-based diet used before the development of breast cancer actually helped to increase the immunity of the mice. It was also pointed out that the use of genistein in such a fashion prevented autophagy – a process that would otherwise allow cancer cells to survive after the treatment and potentially lead to the tumor beginning its development once more. As a result, the test was a success in preventing the recurrence of the cancer after its treatment.
On the other hand, the group that was only fed genistein after the tumor was already developed did not benefit from this increased immune response. The difference was that mice consuming genistein as adults faced a 33% chance of recurrence, compared to the smaller 7% chance linked to the other group.
As Hilakivi-Clarke concluded, this mouse model study has fully explained the contradictory results obtained through both the observation of human patients and that of previous laboratory mice that were fed a genistein diet. As a result, the issue of whether to use soy products or supplements while receiving treatment for breast cancer is much less straightforward than oncologists previously thought.
Even though additional studies may be necessary to understand the exact reason why the timing of soy and genistein introduction is so important, the study shows promising results regarding the use of soy and genistein-based diets and products to ensure the prevention of recurring breast cancer cases.