Both conventional wisdom and clinical trials have supported blocking aromatase for breast cancer patients but when Oncologist speak of an aromatase inhibitor they mean a drug.
Aromatase inhibitors work by blocking the enzyme aromatase, which turns the both hormones stored in fat cells into “bad estrogens” and androgens into estrogens thereby increasing the risk of cancer promotion. The idea is to reduce estrogens, especially in hormone-receptor-positive breast cancer patients.
There are three aromatase inhibitor drugs:
- Arimidex (chemical name: anastrozole)
- Aromasin (chemical name: exemestane)
- Femara (chemical name: letrozole)
Aromatase inhibitors don’t stop the ovaries from making estrogen, so clinically, they are mainly used to treat postmenopausal women. Tamoxifen, though not technically an aromatase inhibitor because its action is to shut-down estrogen production, is generally given to premenapausal women. Both classes of drugs do a good job in removing estrogen, but the cost is high.
Taking tamoxifen may increase your risk of uterine cancer, stroke, or a blood clot in the lung, which can be fatal.
The manufacturer warns to “tell your doctor” if you have:
- a history of stroke or blood clot;
- liver disease;
- high cholesterol or triglycerides (a type of fat in the blood);
- a history of cataracts; or
- if you are receiving chemotherapy or radiation.
It is not known whether tamoxifen passes into breast milk or if it could harm a nursing baby. This medicine may slow breast milk production. You should not breast-feed while taking tamoxifen.
In my experience, most women do NOT like the estrogen-draining effects of tamoxifen!
Aromatase inhibitors tend to cause fewer serious side effects than tamoxifen, such as blood clots, stroke, and endometrial cancer. But aromatase inhibitors can cause more heart problems, more bone loss (osteoporosis), and more broken bones than tamoxifen, at least for the first few years of treatment.
Though it is standard practice to prescribe estrogen-blocking medications in breast cancer patients for at least 5 years post-diagnosis, a recent study revealed continued use may be beneficial: Women who had already completed 5 years of letrozole received either letrozole or placebo for 5 additional years. Five-year disease-free survival was slightly higher with letrozole than with placebo (95% vs. 91%), but overall 5-year survival was similar in the two groups. Because aromatase inhibitors do have adverse effects, discussions on whether to proceed with an additional 5 years of treatment (total, 10 years) should be informed by this trial (NEJM JW Gen Med Aug 1 2016 and N Engl J Med 2016; 375:209).
Is there a Natural Alternative?
When we attempt to support breast cancer patients naturally we typically aren’t trying to block estrogen production like the drugs do; we would rather support healthy, normal elimination of estrogens through proper metabolism. However, some women may over-express estrogen in a state of ‘hyper-aromatization’ and do well on nutrients such as Chrysin, Quercetin, Naringenin, Resveratrol, Apigenin, Genistein, Grape Seed Extract, and Oleuropein, all ‘natural slowers’ of aromatase.
Generally our desire is to support healthy metabolism by supporting the cytochrome P-450 pathways (also look at these genes). Compounds found in vegetables such as cabbage, Brussels sprouts, and broccoli, from the Brassica plant family are essential for this. I3C and DIM, are found in these foods. Glutathione S transferase is also upregulated by the sulfur constituents in cruciferous vegetables so make sure you look at and support genetic defects in the Transsulfuration pathway.
Other nutrients that support healthy estrogen balance may include Norway spruce lignan extract AND Hops extract. Plant lignans are phytonutrients commonly found in small amounts in unrefined whole grains, seeds, nuts, vegetables, berries, and beverages, such as tea (green tea) and coffee. The friendly bacteria in our intestines convert plant lignans into the “human” lignans called enterodiol and enterolactone. Aromatic-PN is a concentrated, naturally occurring plant lignan called 7-hydroxymatairesinol, which is derived from the Norway spruce (Picea abies). In humans, 7-hydroxymatairesinol is a direct metabolic precursor of enterolactone.
Enterolactone is a phytoestrogen that binds to estrogen receptors and has both weak estrogenic and weak antiestrogenic effects. The latter accounts for much of its cell-protective capacity. Additionally, in vitro work has demonstrated that enterolactone affects aromatase and the biosynthesis of estrogen and has strong free radical scavenging and antioxidant properties.
The protective effect of lignans and enterolactone on tissues, including those of the prostate and breast, is encouraging. At the same time, the estrogenicity of HMR and enterolactone, although milder than estradiol, offers promising applications for women with menopausal concerns. For instance, in a randomized, single-blind, parallel group pilot study, 20 menopausal women taking 50 mg/d of hydroxymatairesinol for eight weeks experienced half as many hot flushes as compared to pretreatment. Furthermore, high serum enterolactone has repeatedly been associated with cardiovascular health.
Fermented soy may also be a great addition to help balance estrogens.
Aromatase Inhibiting Medications
- Block the conversion of other hormones to estrogens
- Are widely perscribed in breast cancer patients, especially those that are post-menapausal
- Carry the risk for numerous dangerous side-effects
- Block the production of all estrogens
- Are widely perscribed to pre-menapausal breast cancer patients
- Carry the risk of numerous dangerous side-effects and unwanted changes and symptoms