Kefah Mokbel, Chair of Breast Cancer Surgery at The London Breast Institute, shared on LinkedIn:
“Soy after breast cancer: should women really avoid it? New evidence offers reassurance.
Phytoestrogens – naturally occurring compounds found in foods such as soy and flaxseed – have long raised questions among women diagnosed with breast cancer.
Because these compounds can interact with estrogen receptors, a common concern is:
Could eating phytoestrogen-rich foods increase estrogen levels or the risk of breast cancer recurrence?
A newly published systematic review examined the evidence from randomized controlled trials, including 4 trials and 1,698 women with breast cancer.
What did the authors find?
The available trials did not show an increased risk of breast cancer recurrence with phytoestrogen intake.
They also did not show increases in circulating estrogen levels. In fact, the studies generally showed trends toward lower estrogen concentrations, although most differences were not statistically significant.
One small trial involving 19 women reported a significant reduction in circulating estrone.
Importantly, the evidence is still limited. Only one randomized trial assessed breast cancer recurrence, none assessed mortality, and several of the hormonal studies were small.
The takeaway
Current randomized evidence does not support routinely advising women with breast cancer to avoid foods containing phytoestrogens, such as soy products.
At the same time, there is not yet enough evidence to recommend phytoestrogen supplements as a strategy to prevent recurrence or improve prognosis.
More large, long-term randomized trials are needed to provide definitive answers.”
Title: Effects of phytoestrogens on prognosis and hormonal markers of breast cancer: A systematic review of randomized controlled trials
Authors: Laurence Poirier, Caroline Diorio
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