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After HRT, Some Health Risks Remain

By Kathleen Doheny

HRT and Health Risks: Study Details
Heiss and his colleagues followed up 15,730 of the 16,608 women who participated in the original study, the WHI, designed to examine the health effects of taking estrogen plus progestin in older women. The WHI study was halted in 2002, after an average of 5.6 years of treatment, when researchers found an increased breast cancer risk among those who took the hormone therapy vs. those who took a placebo.

During the trial, they also found hormone users were at higher risk of heart disease, stroke, and blood clots than were nonusers but at lower risk of colorectal cancer and fractures.

In the new follow-up study, conducted from July 2002 to March 2005, Heiss' team looked at the effect that stopping the hormones had on six outcomes: heart disease, stroke, blood clots in the lungs (pulmonary embolism), invasive breast cancer, colorectal cancer and hip fracture.

HRT and Health Risks: Findings
"We have some good news," says Rowan T.Chlebowski, MD, PhD, a medical oncologist at the Los Angeles Biomedical Research Institute in California and another study researcher. "The cardiovascular disease risk really ended once you stopped the hormones."

The risk for cardiovascular problems, including heart attacks, strokes, and lung blood clots, was comparable for the former users and the nonusers. While former HRT users had 343 such "events," nonusers had 323.

After the HRT was stopped, the risk of fractures was similar among former users and nonusers, indicating the protective effect of the hormones disappeared once they were stopped. The rates of colorectal cancer didn't differ in a significant way between the two groups, either, indicating the protective effects found with HRT against colorectal cancer disappeared too.

The risk of breast cancer stayed elevated during the follow-up. "Women on HRT had a 27 percent increased risk" of breast cancer compared to nonusers, Chlebowski says. While 79 former HRT users developed breast cancer during the follow-up, 60 nonusers did. However, the differences are not statistically significant, Chlebowski says.

When looking at the breast cancer risk, say Heiss and Chlebowski, it may have been a bit too soon for the breast cancer risk to decline. "We do see a tendency toward the breast cancer risk going down," Heiss tells WebMD.

The other troubling cancer finding: "Women on HRT had a 24 percent greater risk of all [invasive types of] cancer compared to women on placebo," Heiss says. While 281 of the former HRT users developed cancer during the follow-up, 218 nonusers did. Still, Heiss says, "that is not overly alarming."

Chlebowski says the finding is "concerning" and warrants more study. Why other cancers, including lung cancer, were more common among former HRT users than nonusers is a mystery, he says.