Among postmenopausal women, current use of menopausal hormone therapy may double the risk for developing several hormone receptor-positive breast cancers, according to a case-control analysis published in PLOS ONE.
“Breast cancer risk increases with increasing duration of use of [menopausal] HT,” Usha Salagame, MSc, program manager at the Centre for Health Record Linkage, Centre for Epidemiology and Evidence, New South Wales (NSW) in Sydney, and colleagues wrote in the study background. “A total of around 500,000 women in Australia were estimated to use [menopausal] HT in 2013-14, which includes 13% of Australian women aged 50-69 years, with about 75% of these women using [menopausal] HT for 5 years. Therefore, use of [menopausal] HT, and the risks associated with its use, remains an important issue in clinical practice in these settings.”
Salagame and colleagues analyzed data from the case-control NSW Cancer, Lifestyle and Evaluation of Risk (CLEAR) study, which recruited residents of New South Wales between 2006 and 2014 with a self-reported diagnosis of any type of invasive cancer or who were recruited as cancer-free controls. Researchers included patients who were postmenopausal at recruitment with a breast cancer diagnosis from 2008 or earlier, with pathology information available to diagnose estrogen receptor-positive or progesterone receptor-positive status (n = 399), as well as 324 cancer-free controls. Researchers used binomial logistic regression models to assess the relationship between current, past or never use of menopausal HT to breast cancer risk, for all breast cancer subtypes considered together, and multinomial logistic regression with four levels of the outcome variable: double receptor-positive cases, single receptor-positive cases, double receptor-negative cases and cancer-free controls.
Researchers found that, compared with never use of HT, current use of menopausal HT was associated with a twofold increased risk for developing estrogen receptor-positive breast cancer (adjusted OR = 2.04; 95% CI, 1.28-3.24), as well as estrogen and progesterone receptor-positive breast cancer (aOR = 2.29; 95% CI, 1.41-3.72).
Additionally, current menopausal HT use was associated with increased risk for developing estrogen and progesterone receptor-positive and human epidermal growth factor receptor-2-negative (HER-2-negative) breast cancer (aOR = 2.3; 95% CI, 1.42-3.73) vs. never use of HT. No other breast cancer subtypes based on estrogen or progesterone receptor expression were associated with current menopausal HT use. Past use of menopausal HT was also not associated with breast cancer risk, according to researchers.
“Our results are consistent with prior work in the USA, in which ecological studies have reported declines in the population level incidence of [estrogen receptor-positive] cancers concurrent with the widespread decline in [menopausal] HT use in the population during the period following the publication of the first results from the WHI trial,” the researchers wrote, adding that similar increases in risks were observed in the Nurses’ Health Study, the California Cohort Study and the Melbourne Collaborative Cohort Study.
The researchers noted that the study findings “provide additional support to the current recommendations and help to reinforce the current messaging around limiting the use of [menopausal] HT for the shortest time possible, for the alleviation of moderate to severe menopausal symptoms in women who are informed of the risks and benefits.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.