Dietary Soy and Breast Cancer

There has been some controversy over the benefits of soy. Many scientists have been looking at this issue and the result is quite interesting. If you know anyone who's had breast cancer, please forward this article to them.

Dietary Soy Linked to Lower Risk for Breast Cancer Death, Recurrence

Laurie Barclay, MD
Freelance writer and reviewer, MedscapeCME

December 14, 2009 — Dietary soy intake among Chinese women with breast cancer is significantly associated with lower risk for death and recurrence, according to the results of a large, population-based cohort study reported in the December 9 issue of the Journal of the American Medical Association.

"Soy foods are rich in isoflavones, a major group of phytoestrogens that have been hypothesized to reduce the risk of breast cancer," write Xiao Ou Shu, MD, PhD, from Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues. "However, the estrogen-like effect of isoflavones and the potential interaction between isoflavones and tamoxifen have led to concern about soy food consumption among breast cancer patients."

The study goal was to determine the association of dietary soy intake after diagnosis of breast cancer with total mortality and cancer recurrence. In the Shanghai Breast Cancer Survival Study of 5042 female breast cancer survivors in China, women 20 to 75 years of age who were diagnosed between March 2002 and April 2006 were recruited and followed up through June 2009.

At about 6 months after cancer diagnosis, participants provided information on cancer diagnosis and treatment, lifestyle exposures after cancer diagnosis, and disease progression. Three follow-up interviews at 18, 36, and 60 months after diagnosis allowed updating of this information. To obtain survival information for participants who were lost to follow-up, the investigators used annual record linkage with the Shanghai Vital Statistics Registry database. Disease and treatment information were verified from medical record review....

......."Among women with breast cancer, soy food consumption was significantly associated with decreased risk of death and recurrence," the study authors write.

"In this population-based prospective study, we found that soy food intake is safe and was associated with lower mortality and recurrence among breast cancer patients," the study authors conclude. "The association of soy food intake with mortality and recurrence appears to follow a linear dose-response pattern until soy food intake reached 11 grams/day of soy protein; no additional benefits on mortality and recurrence were observed with higher intakes of soy food. This study suggests that moderate soy food intake is safe and potentially beneficial for women with breast cancer."