Controlling Estrogen Levels to Limit Risk in ER+ Cancers

Controlling estrogen levels to limit risk of recurrence in ER + cancers

Soy has positive benefits for many cancers, including breast

• Soy foods stimulate the immune system and inhibit growth signals, signals to build a new blood supply to the tumor (angiogenesis) and aromatase (which otherwise converts other circulating hormones into estrogen.

• Promotes cell differentiation and maturation

• Soy is especially helpful during periods of breast tissue growth during adolescence and should be encouraged in the diet of young girls.

• And estrogens that are produced are less carcinogenic, and less likely to promote growth of cancer cells

Soy intake was initially controversial because of its role as a “weak estrogen”, as a phyto (plant) estrogen that can bind at the estrogen receptor, sending a weak signal into the cell.

• Several studies have contradicted that concern, including the Shanghai study of breast cancer survivors which found no evidence of harm from eating soy products, and some improvement in survival rates

• Moderate use of soy foods, within a plant-based diet is supported by the American Cancer Society (ACS) and  the American Institute of Cancer Research (AICR)Levels should not exceed the isoflavone levels in the typical Asian diet, around 40 – 50 mg/day= ½ c of soybeans, tofu, or tempeh, or one cup of most soy drinks. Isoflavones make up about ~3 mg per gram of soy protein in the food. www.soyfoods.org

• Avoid taking isoflavone supplements, or highly fortified foods.

Factors That Modify Estrogen Balance

Producing better forms of estrogen, linked to 30% less risk of breast cancerEstrogen can be hydroxylated at the 2, 4, and 16 position, with different impacts on cancer risk.

• 5 – 7 servings as week of cruciferous vegetables (Indole-3-Carbonate)

• Exercise, green tea, (soy), coffee

Higher Levels of Sex Hormone Binding Globulin (SHBG) keep estrogen bound in blood, limiting its ability to stimulate breast cells

• Moderate carbohydrate diet: resulting in lower insulin levels, increases SHBG levels

• Exercise, low fat diet, high fiber, (soy)

Limit the activity of Beta Glucuronidase (B-G), an enzyme in the GI tract, to limit reabsorption of estrogen that would otherwise be excreted in the stool.

• Low animal fat diet, cruciferous vegetables/calcium-d-glucarate

• High fiber (30 – 35 g/day), a goal met by including whole grains and following the plate model for meals.

• Probiotics lower the acidity in the gut, making the B-G enzyme less active

Limit estrogen production in the body

• Limit alcohol, include exercise, and manage weight (BMI > 27 doubles levels)

Remove sources of artificial/outside estrogens and endocrine disruptors

• Avoid hormone replacement therapy, which is metabolized to the 4-OH and 16-OH forms

• Choose low or fat-free dairy products, rBST free

• Avoid xenoestrogens: bisphenol A, phthalates(plastics) parabens (cosmetics)

• Choose BPA free plastics and heat in glass rather than plastic dishes

Strongly consider drug therapies recommended by your oncologist to control the amount of estrogen produced in your body and to block it’s impact.

Tamoxifen: Typically used in women who are still premenopausal, working to block the ability of estrogen to bind to cancer cells. It reduces risk of a new diagnoses or recurrence at 5 years by 50%, and 25% at 10 years

Your oncologist will test to ensure this will be an effective treatment for you, since some women cannot produce the active metabolite: endoxifen. Coffee may increase activation of the enzyme producing the active metabolite.

Drugs that can at least theoretically interfere with Tamoxifen include  paroxetine, fluoxetine, Welbutrin, duloxetine, benadryl, cimetidine, and turmeric

Aromatase inhibitors (AI): Typically used in post-menopausal women, as it reduces the last remaining source of estrogen in the body after the ovaries stop producing it. Our fat reserves contain and enzyme, aromatase, that can take other circulating hormones and convert them to estrogen. Blocking the activity of this enzyme reduces recurrence by 60%, and development of a new primary breast cancer by 75%. 

The primary side effect of reducing estrogen levels so effectively is joint pain, but ensuring that your blood levels of vitamin D levels are within the normal range has been shown to help limit this.