Menopausal Hormone Replacement Therapy and Increased Risk of Breast Cancer
According to new findings from a meta-analysis of worldwide epidemiologic evidence published in The Lancet by a Collaborative Group on Hormonal Factors in Breast Cancer, the risk of breast cancer increased steadily with the length of hormone replacement therapy. The increased risk of breast cancer was reported to be higher with estrogen-progestogen hormone therapies than with estrogen-alone hormone therapies.
“The link between hormone replacement therapy and an increased risk of breast cancer has been known for some time,” stated Professor Martin Marshall, Vice Chair of the Royal College of General Practitioners in the United Kingdom (RCGP), in an RCGP press release. “There is still a lot of evidence to suggest that hormone replacement therapy is safe and effective, and current clinical guidelines recommend it as an appropriate treatment for some women going through menopause. Nevertheless, it is important…that this study is taken into account as clinical guidelines are updated and developed.”
The research was based on 58 studies including 108,647 postmenopausal women; the average age that breast cancer was identified was 65 years. Of those women, 51% had used menopausal hormone replacement therapy. The average use of the therapy was 10 years in current users and 7 years in past users.
The increased risk of breast cancer was greatest among current users of hormone replacement therapy. Past users had some risk, which even continued for more than 10 years after therapy ended. For those who used the therapy for up to a year, there was little risk. Even with 1 to 4 years of use, there was an increased risk, which became greater with longer use.
“For women of average weight in developed countries, 5 years of menopausal hormone therapy, starting at age 50, would increase breast cancer incidence at ages 50–69 by about 1 in every 50 users of estrogen plus daily progestogen preparations; 1 in every 70 users of estrogen plus intermittent progestogen preparations; and 1 in every 200 users of estrogen-only preparations,” the investigators wrote.
Disclosure: The study authors’ disclosure information can be found at thelancet.com.