Early results from a study suggest that testosterone implanted under the skin (subcutaneously) as a pellet about every 3 months helped ease menopausal symptoms without raising a woman’s risk of breast cancer.
The results were published online on Sept. 3, 2013 by the journal Maturitas. Read the abstract of “Reduced breast cancer incidence in women treated with subcutaneous testosterone, or testosterone with anastrozole: A prospective, observational study.”
Menopausal symptoms such as hot flashes and night sweats can dramatically reduce quality of life for some women. Some women use hormone replacement therapy (HRT) to ease these symptoms. But research has shown that HRT increases breast cancer risk in women who haven’t been diagnosed. HRT also increases the risk of breast cancer coming back (recurrence) in women who have been diagnosed with the disease. HRT is not recommended for women who’ve been diagnosed with breast cancer. Undiagnosed women who have severe menopausal symptoms need to weigh the benefits of HRT against its risks.
Earlier research has shown that giving testosterone subcutaneously may ease several menopausal symptoms, including hot flashes, sleep problems, irritability, and fatigue. While testosterone is considered a male hormone because men have much higher levels, women do have testosterone. In men, testosterone is made by the testes. In women, the hormone is made by the ovaries and adrenal glands. Testosterone helps maintain:
- bone density
- fat distribution
- muscle strength and mass
- red blood cell production
- sex drive
- sperm production (in men only)
In women, the enzyme aromatase converts some testosterone to estradiol, a type of estrogen. Because HRT has been found to increase breast cancer risk, doctors believe that estradiol converted from testosterone could affect breast cancer risk.
In this study, called the Testosterone Implant Breast Cancer Prevention Study, the researchers wanted to see if using testosterone instead of the hormones in HRT -- estrogen and progesterone -- to treat menopausal symptoms would increase the risk of breast cancer.
Since March 2008, 1,268 postmenopausal women with no history of breast cancer who had menopausal symptoms were treated with a testosterone pellet implanted under the skin about every 3 months. None of the women were taking HRT. The women were about 52 years old when the first pellet was implanted.
Because doctors believe that estradiol converted from testosterone could affect breast cancer risk, some of the women were treated with pellets that also contained the aromatase inhibitor Arimidex (chemical name: anastrazole). Aromatase inhibitors are the most common type of hormonal therapy medicines used to lower the risk of breast cancer recurrence in postmenopausal women diagnosed with early-stage hormone-receptor-positive breast cancer. Aromatase inhibitors work by blocking aromatase. In women who had the testosterone-Arimidex pellet implanted under the skin, less testosterone was converted into estradiol.
The women are being followed for 10 years. This study reported results from the first 5 years of follow-up.
As of March 31, 2013, eight cases of breast cancer had been diagnosed in the 1,268 women (0.63%). This means that there would be 142 cases of breast cancer per 100,000 person-years of follow-up:
- six of the eight cancers were stage I
- five of the stage I cancers were HER2-negative
In a study like this, each woman in the study is being followed for at least 10 years. One woman followed for 5 years without developing breast cancer is considered to contribute 5 person-years of follow-up.
Studies looking at breast cancer rates among HRT users have found:
- 380 cases per 100,000 person-years of follow-up in women using HRT compared to 300 cases per 100,000 person-years in women not using HRT (Women’s Health Initiative)
- 501 cases per 100,000 person-years in women using HRT compared to 337 cases per 100,000 person-years in women who used HRT in the past, and 238 cases per 100,000 person-years in women who never used HRT (Million Women Study)
Average breast cancer rates in the United States are:
- 234 per 100,000 person-years for women aged 50 to 54
- 293 per 100,000 person-years for women aged 55 to 59
- 358 per 100,000 person-years for women aged 60 to 64
So this study seems to show that using the testosterone implant, with or without Arimidex, actually lowered the risk of breast cancer. Still, the researchers pointed out that the study didn’t have a control group of similar women who didn’t get testosterone implants. So we can’t say for sure if using testosterone implants to treat menopausal symptoms reduces the risk of breast cancer.
The researchers also found that:
- None of the women who developed breast cancer while being treated with the testosterone implant had a cancer recurrence.
- The testosterone implant caused only mild side effects in some women, including an increase in facial hair, hair thinning, and a mild increase in acne; at the same time, about half of the women said their skin improved while being treated with the implants.
- Women who were treated with the testosterone-Arimidex implant had no side effects related to Arimidex.
While these results are promising, they are still EARLY results. The researchers are continuing the study and plan to report more results as they’re collected. Also, testosterone pellets are not approved by the U.S. Food and Drug Administration to treat menopausal symptoms and aren’t commonly used for this purpose.
If you’re having troubling menopausal symptoms, talk to your doctor about all your options. Ask how you can minimize your risk of breast cancer AND relieve your symptoms. Be sure to discuss the pros and cons of currently available HRT options. Research suggests that estrogen-only HRT increases breast cancer risk less than combination HRT, which contains estrogen and progesterone. If you do decide to take HRT, ask if you can take a lower-dose formula and try to take it for the shortest time possible. You also may want to ask your doctor about vaginal or transdermal HRT.
Some complementary and holistic medicine techniques have been shown to ease hot flashes, including exercise, yoga, cognitive behavioral therapy, and acupuncture.
You can learn more about menopause and steps you can take to ease bothersome symptoms in the Breastcancer.org Managing Menopausal Symptoms pages.