Studies Offer Insight Into Breast Cancer Risk and Mortality for Former HRT Users

A brief from this year's San Antonio Breast Cancer Symposium that discusses several new studies that examine the use of hormone replacement therapies and their effects on breast cancer risk and mortality.

There’s good news for women who took hormone replacement therapy: If you stopped taking HRT, your chance of getting cancer drops dramatically, and if you do get cancer, you’re more likely to survive.

For women who used HRT and were later diagnosed with breast cancer, new data presented on Saturday in San Antonio suggest they are less likely to develop a lethal form of the disease than women who did not take HRT.

More than 2,700 postmenopausal women diagnosed with breast cancer between 1995 and 2005 were followed as part of the ongoing California Teachers Study. After taking into account variables such as general health, tumor characteristics, and the type of treatment received, women who used combined HRT (estrogen plus progestin) were 47 percent less likely to die of the disease. Estrogen-only HRT also reduced mortality risk, but after adjusting for the variables mentioned previously the reduction was not enough to be considered statistically significant.

Sarah

Marshall

MA

University

California Irvine

of

HRT users tend to have smaller, less aggressive tumors that are hormone receptor-positive, which makes them more sensitive to anti-estrogen therapies, said lead investigator , , senior statistician at the , at a press briefing.

Although the California Teachers Study didn’t address the risk of getting breast cancer for HRT users, another study presented on Saturday did. Additional analyses of the Women’s Health Initiative—the study reported in 2002 that linked HRT to the development of breast cancer—found that breast cancer risk rapidly declines after women stop taking combined HRT.

But even more significantly, the data demonstrate for the first time that the risk reduction is unrelated to a change in mammography utilization. “The question had always been, is the change in diagnosing breast cancer related to the fact that you’re not looking because you’re not doing mammograms? And you can see in both cohorts (HRT users and non-users) that mammogram use stayed the same [over time],” WHI lead investigator Rowan Chlebowski, MD, PhD, told reporters.

Commenting on results from the California Teachers Study, Chlebowski added that his study did not find any evidence of improved survival in combined HRT users diagnosed with breast cancer.

Read more of CURE's coverage of the 31st annual San Antonio Breast Cancer Symposium at http://media.curetoday.com/htmlemail/sabcs.