Soy Isoflavones in the Management of Breast Cancer Survivors: A Judgment Call

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Author: Tori Hudson
Date: Oct. 2001
Publisher: The Townsend Letter Group
Document Type: Article
Length: 4,804 words

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Breast cancer is one of the most important health problems facing Western women today. Approximately 180,000 new cases will be diagnosed in the United States this year and 45,000 women will die from the disease each year. Risk factors for breast cancer incidence are complex, multifactorial, and not completely understood. Established risk factors include nulliparity late age at first pregnancy, early menarche, late menopause, obesity, alcoholism, first degree relative with breast cancer, inheritance of BRCA1 and BROA2 gene mutations and exposure to ionizing radiation.

There is also strong epidemiological evidence that diet also has a role in the etiology of breast cancer.' This evidence has predominantly come from population studies, and subsequently cohort and case-control studies. Many of these studies have focused on dietary fat and the hypothesis that a diet high in fat can increase the risk of breast cancer. A review of some of the pertinent findings will be helpful in sorting out the complicated data. About 30 years ago, the fat intake of many countries, was plotted on a graph against breast cancer rates. [2] With few exceptions, the more dietary fat that individuals in that society consumed, the higher the risk of breast cancer. Ten out of ten international studies looking at large differences in fat intake from one country to another continued to confirm this relationship between higher dietary fat levels and higher rates of breast cancer. By and large, women who live in cultures with the lowest fat intake like Japan and Thailand have the lowest rates of breast ca ncer. Women in the Middle East who have medium amounts of fat in the diet have medium rates of breast cancer. Women in Europe and North America with the highest intake of dietary fat have the highest rates of breast cancer.

However, in 1992, the Nurses' Health Study group found no such link.[3] There have been many critiques of this study that have pointed out the inaccuracy of the measurements used and results obtained; but perhaps the most compelling at the time was the criticism of the five categories of dietary fat analyzed. The most glaring deficiency was that the group with the lowest amount of fat was still only slightly lower than 29%. This is notably higher than the 20% many researchers believe to be the beginning of where women would receive the protective benefit of a low fat diet. In March of 1999, a follow-up analysis of 88,795 women extended the Nurses' Health Study for another 6 years and more than 1500 cases. [4] This extended study is now considered large enough and long enough to assess the effect of less than 20% fat intake as well as examining risks of different types of fat. Surprising to many, they saw no increased risk of breast cancer with increased intake of animal fat, polyunsaturated fat, saturated fa t, or trans-unsaturated fat . They also found no evidence of decreased risk of breast cancer withincreased intake of vegetable fat or monounsaturated fats. Also contrary...

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Gale Document Number: GALE|A78900862