HRT Alternatives and Breast Cancer

Summarized by Robert W. Griffith, MD
May 7, 2004

Introduction

Since the collapse of hormone replacement therapy (HRT) as a safe way to protect women from the effects of the menopause, numerous alternatives have been suggested. Some of the most popular have centered on botanical products that contain estrogen-like compounds (see the first link below). Those called phytoestrogens contain isoflavones and lignans. Soy foods are rich in isoflavones, which resemble estrogen in their structure, and which can act both as estrogens and anti-estrogens.

Soy is eaten a lot in Asian countries, and some experts claim that it can reduce the risk of breast cancer. On the other hand, its estrogen-like properties, which are presumably responsible for its benefits in treating the symptoms of menopause, give rise to the fear that it could increase the risk of breast cancer.

Scientists from the Netherlands have completed a large study investigating a possible link between breast cancer and the intake of isoflavones and lignans; it's now been published in the American Journal of Clinical Nutrition.

What was done

The population studied was the Dutch part of the European Prospective Investigation into Cancer and Nutrition. Over 17,000 women living in or near Utrecht were enrolled between 1993 and 1997. They completed food-frequency questionnaires, and had a physical exam to ensure good health at entry.

The Netherlands health records allowed all cases of cancer occurring in the women to be listed. If someone without cancer died, left the country or otherwise was lost to follow-up, they were recorded as 'no cancer' up to the time of their loss.

Laboratory analysis data were used to calculate the phytoestrogen and lignan content of the food items given in the food-frequency questionnaires. Participants were divided into 4 equally-sized groups for each diet constituent - low, low-mid, mid-high, and high. (These are called quartiles.) The frequency of breast cancer in each quartile was estimated, and then the risk of getting breast cancer was calculated for the different phytoestrogen consumption groups.

What was found

Of the original women enrolled, 15,500 provided adequate information for inclusion in the final analyses. There were 280 cases of newly-diagnosed breast cancer during the follow up period, which averaged 5.2 years. Their ages ranged from 49 to 70, and ¾ of them were post-menopausal.

The participants who had the greatest intake of phytoestrogens - the 4th quartiles - were generally younger, older at delivery of their first child, were non-smokers, taller, had lower BMIs, and ate more fruit, fiber, soy and vegetables than the other quartiles.

When the analyses were made for possible associations between the intake of phytoestrogens and breast cancer, none were found. This was the case even after adjustments to allow for possible influence of factors like age, height, BMI, and so on. There appeared to be a hint of a possible 'protective' effect of high consumption of lignans, but this finding was not statistically significant, i.e. it could have occurred by chance alone.

What this means

This study shows that a high intake isoflavones or lignans is not linked to a risk of breast cancer. There was no protective effect, but also no negative effect (i.e. no increased risk).

It should be noted that this study was done in a Western country, where dietary isoflavone levels are normally much lower that in Asian countries, due to their high consumption of soy. Lignans occur more frequently in Western diets than isoflavones, being contained in vegetables, fruit, grains, and nuts. Even if these food constituents have a true protective effect on breast cancer risk, it was a small, insignificant effect in this study.

The important conclusion from this study is that, if you are suffering from the effects of menopause and isoflavones help relieve the symptoms, you can consume them without fear of increasing your risk of breast cancer.

Source

• Dietary phytoestrogens and breast cancer risk. L. Keinan-Boker, YT. van Der Schouw, DE. Grobbee,  et al., Am J Clin Nutr, 2004, vol. 79, pp. 282--288

Related Links
Some FAQs Women Ask at Midlife
Natural and Personalized Hormonal Products
Can Herbal Remedies Douse Hot Flashes?

Please take a moment to give us your comments. For questions about Health matters you may check our "Questions & Answers" Portal and Service.