Estrogen and Breast Cancer

Betsy Washburn, MD, Surgical Breast Oncologist

Betsy Washburn, MD, Surgical Breast Oncologist

I talk to a lot of women in my clinic who know that taking estrogen can increase their breast cancer risk but don’t know why. At the start of menopause, a woman’s ovaries will produce less and less estrogen until production stops completely. Women in menopause experience a range of symptoms that affect quality of life like night sweats, mood swings, vaginal dryness, a drop in sex drive and more. Hormone replacement therapy is often recommended to alleviate these annoying symptoms and help women while their hormone levels are fluctuating wildly. Estrogen therapy, estrogen/progesterone combination therapy or bioidentical hormones provide real benefits like protection from heart disease and increased bone strength, yet many women do not understand how these medications also impact their risk of developing breast cancer.

It’s important to note that 80 percent of all breast cancers are fueled by estrogen – meaning they become more active and grow more quickly when estrogen is present in the body. Breast tissue is naturally much more active in women in their 20s, 30s and 40s compared to their 50s, 60s and 70s. The body produces less estrogen as you age, which works in women’s favor because one of the biggest risk factors for breast cancer is aging. As your breast cancer risk rises because of age, your estrogen levels are dropping – and this matters because less estrogen in the body means less activity in your breast tissue.

Over time, a woman’s breasts turn from a rubbery consistency to more of a jello consistency – not as dense or active and eventually becomes dormant. Hormonally active breast tissue is denser, has more cysts, is inflamed, and has more tissues that are dividing and growing than inactive tissue. When women take estrogen, the breast tissue remains active for a longer period of time when they are moving into a higher risk category of developing atypical cells and breast cancer.

How long is it safe to be on estrogen therapy?

It’s understandable that many women need relief from menopause, which can cause significant quality of life issues. Yet most women do not need to be on estrogen for an extended period of time. Women who have been on estrogen for 30 years without a change of dosing are unlikely to still need it. 

Just like many other treatment options, it’s important for women to weigh their increased risk of breast cancer against the relief they may gain from hormone replacement therapy. At CHI Memorial MaryEllen Locher Breast Center’s high risk clinic, each woman is evaluated based on her overall breast cancer risk. Women with no family history of breast cancer who don’t smoke or aren’t overweight can likely handle the increased risk from hormone replacement therapy because of the short term quality-of-life improvements.

But women who smoke or have a family history of breast cancer need to strongly consider whether adding another risk factor is worth the symptom relief. At the very minimum, these women should be followed more closely with breast exams and mammograms. All women, no matter how low their other risk factors, should evaluate their need for estrogen therapy every two to three years to ensure it’s still necessary. Many women can decrease their dosage over time, which lessens the overall risk.

Like any decision, it’s important to discuss the pros and cons of estrogen therapy with your doctor – particularly if you are at increased risk for breast cancer because of a family history of the disease or other unmodifiable risk factor. When you understand your risk, you can make the very best decisions for your breast and overall health.

To schedule an appointment with CHI Memorial Breast Care Associates, call (423) 698-0304. 

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