FRIDAY, Dec. 12 (HealthDay News) -- Taking hormone therapy after menopause is known to increase the risk of getting breast cancer, but women who take hormone therapy and then develop breast cancer have a lower risk of dying from the disease, a new study suggests.

Why?

"Hormone therapy seems to give you a particular type of cancer that is easier to treat," explained study author Sarah F. Marshall, a senior statistician at the University of California Irvine. She is to report her finding on Saturday at the San Antonio Breast Cancer Symposium, in Texas.

"We found that women who took hormone therapy before their diagnosis were more likely to be diagnosed with estrogen receptor-positive cancer, as well as having breast cancers that were more favorable in other ways, [such as being] smaller and detected at an earlier stage," Marshall said.

Estrogen-receptor positive breast cancers depend on estrogen to grow. Giving anti-estrogen therapy (such as tamoxifen) treats the cancer.

Marshall and her colleagues evaluated almost 2,800 postmenopausal women who were diagnosed with a primary invasive breast cancer after joining the study in 1995 and 1996. The researchers then tracked outcomes through the end of 2005, or until the women's death.

"We looked at self-reported use of hormone therapy before their diagnosis," Marshall said. "We compared three groups -- those without [current or previous hormone use], those on estrogen alone, and those on estrogen-progestin."

Those taking estrogen-progestin had a 47 percent reduced risk of death from breast cancer during the follow-up compared to those who did not take hormone therapy. Those on estrogen alone had an 18 percent reduced risk of breast cancer death, but that was not statistically significant, she said.

The study results may be somewhat reassuring for women who took hormone replacement therapy, she said.

The finding is not surprising, said Dr. Victor G. Vogel, the incoming national vice president of research for the American Cancer Society and a professor of medicine and epidemiology at the University of Pittsburgh. "It says if you are taking HRT, your risk of getting breast cancer is higher, but your risk of dying from breast cancer is less," he said.

The finding may be surprising, he added, to those who don't appreciate the complex interaction between estrogen and breast cancer, which is still something of a paradox, he said.

In other presentations at the conference, researchers reported that:

• Estrogen therapy may help women with metastatic breast cancer whose tumors stopped responding to anti-estrogen therapy. Giving the estrogen may return metastatic tumors to a vulnerable state after which patients can then be cycled back to the anti-estrogen therapy. The concept is not new, Vogel noted.
• A switch to the drug anastrazole after one to four years of tamoxifen boosts disease-free survival by about 31 percent, according to another study, but patients report worse quality of life. But quality-of-life issues can generally be treated and improved, Vogel said.
• The drug letrozole may beat out tamoxifen in improving overall survival in patients with primary breast cancer. A comparison study of the two found that letrozole reduces breast cancer recurrence and may decrease the risk of breast cancer death by 13 percent.

• More News on Breast Cancer
• More News on Hormone Replacement Therapy

Related MedlinePlus Pages:

• Breast Cancer
• Hormone Replacement Therapy