October was Breast Cancer Prevention month, and as always, fund raising and education initiatives were everywhere. There are many advances in our understanding of how breast cancer develops, yet out of all the articles I saw in the mainstream media, none of them explained the most important factors influencing breast health.

Most breast cancer is the type that is called hormone sensitive. That means it is cancer that forms in response to estrogen. It is usually implied that it is solely a matter of having too much estrogen (and/or other compounds that have estrogen-like structure) in the body. However if you dig deeper, you learn that it is not so much the estrogen itself, but how it is being metabolized in the body and whether it is balanced by adequate progesterone that are the primary problems.^1-2

Estrogen/Progesterone Balance

The balance between estrogen and progesterone is very important for breast health and is almost never mentioned in popular literature on hormone sensitive breast cancer. There is a big misunderstanding among some people in the medical community that progesterone increases breast cancer risk. This was due to studies that found that synthetic progestins formerly used in women on hormone replacement therapy did increase breast cancer risk. However, further study has clarified that natural progesterones do not.³

Natural (bio-identical) progesterone actually reduces the production of certain growth factors, and increases a process called apoptosis (cell death) in proliferating breast cells. Several studies have shown that women with progesterone deficiency have anywhere from 4 to 6 times the risk of developing breast cancer.⁴

Estrogen Metabolism

As estrogen breaks down in the body from the primary estrogen in the body, estradiol, it can convert to a form called 2OH estrone, the good metabolite, or to 16OH and 4OH estrones, forms that cause tissue proliferation. 16OH contributes to endometriosis for instance, the over-proliferation of uterine lining tissue that causes painful menstrual cramps and can reduce a woman’s ability to conceive. These metabolites also increase the risk of breast cancer. On the other hand, women with a higher 2OH to 16OH ratio have a 40% less chance of developing breast cancer.

There is a second step in the breakdown of estrogen called methylation. This step takes 4OH and makes it less active in tissues and actually makes a form of estrone (called 2-methoxyestrone) which inhibits breast cancer. So if your methylation pathways are purring along wonderfully you can break estrogen down into beneficial metabolites. Key nutrients to support methylation are the B vitamins, folate, B6 and B12, and dietary sulfur (found in onions, garlic, cabbage family vegetables and in foods like whey and eggs).

The final step for estrogen breakdown is glucuronidation, a metabolic process in which the different estrogens bind with glucuronic acid in the liver and from there get excreted in the GI tract. At least that’s what should happen. Magnesium is needed for glucuronic acid to bind with estrogen. If you aren’t taking in enough, the estrogen will not be bound and will just continue circulating in the body.

Gut flora also influences glucuronidation. Pathogenic (harmful) bacteria in the intestines can cause estrogen to get uncoupled from the glucuronic acid. So instead of being carried out of the body, the estrogen re-enters circulation, and the woman will accumulate too much in her system. This pathogenic bacteria called beta-glucuronidase is associated with increased cancer risk.

Diets high in fiber and beneficial flora reduce beta-glucuronidase levels, and so promote good estrogen metabolism. A form of calcium called D-glucarate inhibits beta-glucuronidase and so is also a very helpful nutrient.

There are a couple of substances in foods that help healthy estrogen metabolism and have significant and strong evidence of being cancer protective. (See Laura’s article for more information on that.) This is where most of the articles in popular women’s magazines focus — eating a diet that is high in these cancer protective substances; and while it is important to eat this way, unless you measure your estrogen metabolites with urine or saliva testing, you have no way of knowing if your diet is directing your metabolism to more of the healthy and fewer of the bad estrogen metabolites. (My new e-book explains estrogen testing in detail. Look for The Keys to Healthy Aging: Making Hormone Replacement Work for You, available from Total Health Breakthroughs in a few weeks.)

Other Influences: Thyroid and Insulin

The other two influences on breast cancer you rarely read anything about are thyroid health and high insulin levels. Laura’s article discusses the diet and insulin connection to breast health, but medicine has known for some time that women with breast cancer have a higher than average degree of thyroid problems, including autoimmune thyroid disease and hypothyroidism.

We know now that any disease of autoimmunity raises cancer risk.⁵ Since it is known that people with autoimmunity have a suppression of natural killer cells, the cells that can fight and overcome cancer cells, this shouldn’t be surprising. You may think that autoimmune thyroiditis and hypothyroidism are not that common, but they in fact are second only to diabetes as the most common endocrine disorders — and they occur in anywhere from 10 to 30% of the population.^6-7

To really get proactive against breast cancer, all women can and should get tested for the following:

• Estradiol, estrone, progesterone, and estrogen metabolites.
• Low thyroid and thyroid antibodies if you have any reason to suspect your thyroid is under-active.
• Post-prandial glucose and insulin levels to ensure you are not developing insulin resistance.

Once you have an accurate reading on these vital hormone levels, an appropriate supplementation and dietary plan can be applied as needed.

References

1. Kabat GC, et al. Epidemiology. 2006;17(1):80-8.
2. Adly L, et al. Int J Cancer. 2006;119(10):2402-7.
3. Campagnoll D, et al. J of Steroid Biochem and Mol Biol. 97(5): 441-450.
4. Oldenburg H, et al. Critical Reviews in Oncology/Hematology. 200763(2);125-149.
5. Landgren O. J Natl Cancer Inst. 2006 Sep 20;98(18):1321-30; and Eur J Gastroenterol Hepatol. 2000:12: 645-48.
6. Maruchi N, et al. Mayo Clin Proc. 1976;51: 263-5.
7. E-medicine from webMD. Hashimoto Thyroiditis, May 30, 2006.

[Ed. Note: James LaValle is the founding Director of the LaValle Metabolic Institute, one of the largest integrative medicine practices in the country. Dr. LaValle is the author of the bestselling book Cracking the Metabolic Code: 9 Keys to Optimal Health and is the Executive Editor of THB's The Healing Prescription. To learn more, click here.]