Among the studies we review in this Update are a follow-up of the US Women’s Health Initiative clinical trials and a large observational study from the United Kingdom, which exlore the impact of different hormone therapies (HTs) on breast cancer risk. We look at the interesting patterns found by authors of a study in Canada that analyzed predictors of unnecessary bilateral salpingo-oophorectomy. In addition, we review a study that investigates whether hormone therapy can be effective, alone or adjunctively, in peri- and postmenopausal women with depression. Finally, Dr. Chrisandra Shufelt and Dr. JoAnn Manson summarize highlights from the recent American Heart Association’s scientific statement on the menopause transition and increasing risk factors for cardiovascular disease, and how this period can be viewed as an opportunity to encourage healthy, cardiovascular risk–reducing behaviors.
Studies clarify menopausal HT’s impact on breast cancer risk
Chlebowski RT, Anderson GL, Aragaki AK, et al. Association of menopausal hormone therapy with breast cancer incidence and mortality during long-term follow-up of the Women’s Health Initiative randomized clinical trials. JAMA. 2020;324:369-380. doi: 10.1001/jama.2020.9482.
Vinogradova Y, Coupland C, Hippisley-Cox J. Use of hormone replacement therapy and risk of breast cancer: nested case-control studies using the QResearch and CPRD databases. BMJ. 2020;371:m3873. doi: 10.1136/bmj.m3873.
For many menopausal women, the most worrisome concern related to the use of HT is that it might increase breast cancer risk. In the summer and fall of 2020, 2 important articles were published that addressed how the use of menopausal HT impacts the risk of breast cancer.
The Women’s Health Initiative (WHI) represents the largest and longest-term randomized trial assessing the health impacts of systemic HT. A 2013 WHI report found that with a median of 13 years’ cumulative follow-up, estrogen-only HT (ET) reduced the risk for breast cancer while estrogen-progestin therapy (EPT) increased the risk.1 In a July 2020 issue of JAMA, WHI investigators analyzed longer-term data (cumulative median follow-up >20 years), which allowed assessment of whether these trends (breast cancer incidence) persisted and if they led to changes in mortality from breast cancer.2
WHI data on breast cancer risk trends in ET vs EPT users
In the ET trial, in which Chlebowski and colleagues studied 10,739 women with prior hysterectomy, 238 versus 296 new cases of breast cancer were diagnosed in women in the ET versus placebo groups, respectively (annualized incidence, 0.30% [ET] vs 0.37% [placebo]; hazard ratio [HR], 0.78; P = .005). ET also was associated with significantly lower mortality from breast cancer: 30 versus 46 deaths (annualized mortality, 0.031% [ET] vs 0.046% [placebo]; HR, 0.60; P = 0.04).
In the EPT trial, which included 16,608 participants with an intact uterus, EPT compared with placebo was associated with significantly elevated risk for incident breast cancer: 584 versus 447 new cases, respectively (annualized incidence, 0.45% [EPT] vs 0.36% [placebo]; HR, 1.28; P<.001). However, mortality from breast cancer was similar in the EPT and placebo groups: 71 and 53 deaths (annualized mortality, 0.045% [EPT] and 0.035% [placebo]; HR, 1.35; P = .11).2
For women with previous hysterectomy who are considering initiating or continuing ET for treatment of bothersome menopausal symptoms, the breast cancer mortality benefit documented in this long-term WHI analysis could, as editorialists point out, “tip the scales” in favor of ET.3 Furthermore, the mortality benefit raises the possibility that ET could be evaluated as a risk-reduction strategy for selected high-risk menopausal women who have undergone hysterectomy. Although tamoxifen and aromatase inhibitors are approved for breast cancer chemoprophylaxis in high-risk menopausal women, these agents have not been found to lower breast cancer mortality.2
UK data analysis and risk for breast cancer in HT users
In an October 2020 issue of BMJ, Vinogradova and colleagues described their analysis of 2 primary care databases in the United Kingdom that in aggregate included roughly 99,000 women with breast cancer diagnosed between 1998 and 2018 (age range, 50–79; mean age at diagnosis, 63; >95% White); these were matched with more than 450,000 women without breast cancer (controls).4 Analyses were adjusted for smoking, body mass index (BMI), ethnicity, and mammography.
In this study, ever-use of EPT was associated with an adjusted odds ratio (OR) for breast cancer of 1.26 (95% confidence interval [CI], 1.24–1.29), while ET had an OR of 1.06 (95% CI, 1.03–1.10). In women aged 50 to 59 who used EPT for 5 years or more, 15 additional breast cancers were diagnosed per 10,000 woman-years; for ET users, the attributable risk was 3. Although risk rose with longer HT duration, this trend was less evident with ET than EPT.
In addition, the increased risk associated with ET use was less pronounced in women with a BMI greater than 30 kg/m2. Among EPT users, risks were similar with the progestins medroxyprogesterone acetate (MPA), norethindrone (NET), and levonorgestrel (LNG). Likewise, risks were similar regardless of estrogen dose and route of administration (that is, oral vs transdermal). Vaginal estrogen was not associated with a higher or lower risk for breast cancer. Among past users of ET or EPT (with MPA), no increased risk was noted 5 years or more after stopping HT. For users of EPT (with NET or LNG), risks diminished 5 years or more after stopping HT but remained modestly elevated compared with risk in never-users.4
In this large observational UK study, ET was associated with minimally elevated risk for breast cancer, while in the WHI study, ET reduced the risk for breast cancer. For EPT, the excess risk in both studies was identical. As the authors note, mean BMI in the UK study participants was slightly lower than that in the WHI participants, a distinction that might explain the differing findings with ET use.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
In our practice, for women with an intact uterus who are considering the use of EPT for treatment of bothersome menopausal symptoms, we counsel that long-term use of HT slightly elevates the risk for breast cancer. By contrast, we advise posthysterectomy women with bothersome menopausal symptoms that ET does not appear to increase the risk for breast cancer.
In our practice, for women with an intact uterus who are considering the use of EPT for treatment of bothersome menopausal symptoms, we counsel that long-term use of HT slightly elevates the risk for breast cancer. By contrast, we advise posthysterectomy women with bothersome menopausal symptoms that ET does not appear to increase the risk for breast cancer.
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