Funk: Good News for Women and Breast Cancer

We all know women who have or have had breast cancer and survived. In the soyfoods industry there has always been a question about if women at risk or survivors should eat soyfoods. I have asked Mark Messina, Ph.D. nutrition research expert, to write about the latest research and findings on this subject. And it is good news, please keep reading!

Early interest in health benefits of soy focused on the theory that these foods could reduce breast cancer risk. Research conducted over the past 20 years lends support to this hypothesis but with a twist. Most evidence suggests that soy protects against breast cancer only if it is consumed early in life – that is, during childhood and/or adolescence. For young girls who eat soyfoods, as little as one serving per day could reduce lifelong risk of getting breast cancer.

Despite these findings, there continues to be concern about the safety of soyfoods for women who have breast cancer or are at high risk for this disease. The safety questions are based on research showing that soy isoflavones – compounds that are essentially unique to soyfoods – stimulate estrogen-sensitive breast tumors in mice. Isoflavones are classified as phytoestrogens or plant estrogens. And, since greater lifelong exposure to the hormone estrogen may increase breast cancer risk, there have been questions about whether isoflavones have the same effect.

However, the most recent study to examine this issue shows that soyfoods may actually be beneficial for women with breast cancer. The Women’s Healthy Eating and Living (WHEL) study included approximately 3000 California women with breast cancer, 85 percent of whom were Caucasian. The researchers who conducted this study were from Kaiser Permanente, The Moores Cancer Center, University of California, the Department of Public Health Sciences, UC Davis School of Medicine and the Arizona Cancer Center, University of Arizona. In the seven years following their diagnosis, 448 women experienced a cancer recurrence and 271 women died (81 percent of the deaths were due to breast cancer). The investigators collected information about dietary habits of the subjects two years following their initial diagnosis.

Women who had an average daily intake of 26 milligrams of isoflavones (the amount in approximately one serving of soyfoods such as a cup of soymilk) were 54 percent less likely to have died. Of the women in the study who were taking the breast cancer drug tamoxifen (used to treat estrogen sensitive tumors) a high intake of soyfoods reduced mortality by 74 percent. Previous studies in Chinese and American women have shown similar results, leading the researchers of this study to conclude that there is no need for doctors to advise against soy consumption for women diagnosed with breast cancer.

By Mark Messina

SOURCE: Soy Food Consumption and Breast Cancer Prognosis. Bette J. Caan1, Loki Natarajan, Barbara Parker, Ellen B. Gold, Cynthia Thomson, Vicky Newman, Cheryl L. Rock, Minya Pu, Wael Al-Delaimy, and John P Pierce. Cancer Epidemiology Biomarkers and Prevention, 2011