HRT-Related Breast Cancer Risks Vary

Breast cancer risks varied among women who used hormone replacement therapy

(RxWiki News) In the late 1990s, medicines that helped women with menopausal symptoms, such as hot flashes, were widely prescribed. That changed in 2003 after a large study found that hormone replacement therapy (HRT) increased breast cancer risks.

A new study concluded that HRT did not elevate breast cancer risks in all women.

Race and ethnicity, body mass index (BMI — a measure of body composition) and breast density (amount of fat in breast tissue) impacted breast cancer risks in this study.

HRT did not seem to increase the chances of breast cancer in black and obese women or women who had less dense breasts, the study found.

"Discuss the risks and benefits of all medicines you are prescribed with your physician."

Ningqi Hou, MHS, PhD, from the University of Chicago in Chicago, IL, and colleagues analyzed data from 1,642,824 mammograms and 9,300 women who were diagnosed with breast cancer.

The authors of this study explained that the controversy regarding HRT began after the Women’s Health Initiative (WHI) study showed a 24 percent increase in invasive breast cancer risk among women who used HRT medicines that increase levels of estrogen and progestin, two female hormones. Estrogen drives the majority of invasive breast cancers diagnosed in the US.

A dramatic decline in HRT use followed these findings, and breast cancer incidence decreased between 2002 and 2003 in women over the age of 50, the authors reported.

The research team for this study analyzed information on postmenopausal women from the Breast Cancer Surveillance Consortium, a US registry of mammography screening.

The researchers looked at HRT use among women of different races and ethnic backgrounds, ages, BMIs and breast density.

HRT use increased breast cancer risks among white women by 20 percent, Asian women by 58 percent and Hispanic women by 35 percent. However, black women who took hormone replacement therapy, did not have elevated breast cancer risks, according to study findings.

Women with low to normal BMIs of 25 or less and extremely dense breasts more glandular tissue and less fat) who used HRT had the highest breast cancer risk increase — 49 percent — compared to nonusers.

No increased breast cancer risks were seen in women who were overweight (BMI of 25 or more) or obese (BMI of 30 or more).

An accompanying editorial by Mary Beth Terry, PhD, and Parisa Tehranifar, DrPH, from the Department of Epidemiology and the Herbert Irving Comprehensive Cancer Center at Columbia University in New York, NY, pointed out that this study had a number of limitations.

The types of HRT used and the duration of use were not indicated in the study.

Patrick D. Maguire, MD, a radiation oncologist with Coastal Carolina Radiation and Oncology in Wilmington, NC, told dailyRx News, “While the authors' rightly qualify that their conclusions need to be validated with further studies (due to inherent limitations with their study noted in the accompanying editorial), they do raise the favorable possibility that some subgroups of women (black, obese, and those with less dense breast tissue) may benefit from HRT, when medically indicated, without a significantly increased risk of breast cancer.

"Until that time, even in these potentially lower risk groups, HRT should be used with caution," said Dr. Maguire, who was not involved in this study.

This research was published September 3 in the Journal of the National Cancer Institute.

The American Cancer Society funded this work. No conflicts of interest were reported.

Review Date: 
September 3, 2013
Last Updated:
September 3, 2013