Advice for breast cancer patients

Two separate studies on women with breast cancer followed for at least 5 years suggest that soy food intake (or estimated isoflavone intake) does not have adverse effects on breast cancer survival ^{38 , 39} . Interestingly, Japanese breast cancer patients, when compared to western women, have better survival rates even after controlling for stage of diagnosis ⁴⁰ .

In reviewing the evidence to provide advice for consumers the American Cancer Society in 2006 concluded that up to three servings per day of traditional soy foods are unlikely to be harmful for breast cancer patients ⁴¹ . However, they advised against the use of concentrated sources of isoflavones in the form of supplements and powders.

The Cancer Council New South Wales in Australia also generally supports the consumption of soy foods in the diet as this is consistent with recommendations and national dietary guidelines to eat a diet high in plant based foods. It, similarly, however does not recommend or support the use of supplements such as soy protein isolate or isoflavone capsules for healthy men and women to prevent cancer and for breast cancer survivors ⁴² .