Long-Term Health Effects of Hormone Therapy for Menopause

Understanding Menopause and Perimenopause Health Risks

Natural menopause usually occurs between 44 and 55 years of age when the ovaries stop releasing eggs and substantially reduce hormone production, marked by 12 consecutive months without a menstrual period. Perimenopause acts as the transitional phase beforehand, bringing irregular periods, declining hormone levels, hot flushes, night sweats, and mood changes over several years. According to the review findings, these lower hormone levels can impact a woman’s heart, blood vessels, and bones by increasing cholesterol levels, altering weight and body fat, raising blood pressure, and elevating risks for diabetes, heart disease, stroke, osteoporosis, and reduced physical strength or mobility.

Combined Continuous Hormone Therapy Effects

Combined continuous hormone therapy utilizes both oestrogen and progestogen to protect the womb lining from endometrial cancer in women who still have a uterus. Based on evidence from a major study of 16,608 women measured at roughly 5.5 years of follow-up, combined continuous hormone therapy likely made little or no difference to heart attack or lung cancer risks. However, the data showed that the treatment increased the chance of developing breast cancer from about 19 to 24 women in every 1,000, while reducing bone fracture risks from about 111 to 87 women in every 1,000. The same combined therapy regimen may have also increased the probability of specific adverse events. According to the data, strokes rose from about 13 to 18 women in every 1,000, blood clots in veins increased from about 10 to 20 women in every 1,000, and gallbladder disease requiring surgery grew from about 16 to 27 women in every 1,000.

Oestrogen-Only Therapy Outcomes After Hysterectomy

For women without a womb who have undergone a hysterectomy, oestrogen alone can be prescribed safely without progestogen. Evidence from a study involving 10,739 women tracked over seven years indicated that oestrogen-only hormone therapy probably made little or no difference to heart attack risk, blood clots in veins, or breast cancer development. Lung cancer risk also showed little or no difference under oestrogen-only treatment. Despite those neutral findings on certain major conditions, oestrogen-only therapy carried distinct risks in the trial data. The review noted that oestrogen alone reduced bone fracture chances from about 141 to 103 women in every 1,000. Conversely, it increased the likelihood of a stroke from about 24 to 32 women in every 1,000 and raised gallbladder disease requiring surgery from about 27 to 47 women in every 1,000.

Evidence Limitations and Future Research Needs

Researchers advise caution when evaluating these review results due to ongoing evolution in hormone therapy doses, delivery methods, and types since the foundational trials were conducted in the 1990s and early 2000s. Most data originated from studies administering hormone therapy exclusively as oral pills, which may carry different risk profiles compared to modern transdermal patches or localized delivery systems. Furthermore, approximately 30% of the women in the primary datasets were aged 50 to 59 at baseline, leaving a data gap for younger cohorts. The review authors noted a lack of sufficient data to assess long-term hormone therapy risks in women younger than 50 years or those experiencing medically induced menopause from ovarian failure.