THURSDAY, Jan. 27 (HealthDay News) -- Here's some good news for women ever bothered by hot flashes and other menopausal symptoms: Your risk for breast cancer may be reduced as much as 50 percent, researchers from the Fred Hutchinson Cancer Research Center in Seattle report.

"We know that hormones are important to breast cancer risk, and we also know that menopausal symptoms occur primarily because of changes in hormones that women experience as they go through menopause," said lead author and breast cancer epidemiologist Dr. Christopher I. Li.

Now, for the first time, he said researchers looked at the relationship between menopause symptoms and breast cancer risk.

"If we can confirm this finding, it may be somewhat of a silver lining for women who experience menopausal symptoms, because they can often really reduce a woman's quality of life," he said.

For the study, published in the Jan. 26 online edition of Cancer Epidemiology Biomarkers and Prevention, Li's team questioned to 1,437 postmenopausal women, 988 of whom had been diagnosed with breast cancer.

The women, who were between 55 and 74 years old, were asked about menopausal symptoms, including hot flashes, night sweats, insomnia, vaginal dryness, irregular or heavy menstrual bleeding, depression and anxiety.

The researchers found that women who had the most hot flashes had a very low risk of developing breast cancer, the second leading cause of cancer death among U.S. women.

In fact, for women with the most severe menopausal symptoms, the relative risk of developing either of the two most common breast cancers -- invasive ductal and invasive lobular carcinoma -- was lowered an average of 50 percent, compared to women who reported no menopausal symptoms.

In 2002, a major U.S. study on hormone replacement therapy (estrogen and progestin) was halted early because of an increased risk in breast cancer risk for the women taking the hormones. Li said that since it's known that estrogen and progesterone play a role in breast cancer, reduction of these hormones, which trigger the most severe menopausal symptoms, might be protective, Li said.

Moreover, the association between menopausal symptoms and the risk for breast cancer remained even after taking into account other factors, such as weight and use of hormone replacement therapy, Li noted.

"These findings tell us more about what may cause or prevent breast cancer," Li said. "We certainly wouldn't go around inducing menopausal symptoms to reduce breast cancer risk. But if we can better understand the underlying biological mechanisms, that could help in developing prevention strategies," he said.

Breast cancer oncologist Dr. Stefan Gluck, a professor at the University of Miami's Sylvester Comprehensive Cancer Center, said this study "is another small, but important piece in our mosaic in understanding breast cancer."

The study confirms the suspicion that high levels of estrogen increase the risk of breast cancer, he added. "But we did not have proof that if [women] had less estrogen they have less breast cancer."

The reduction in risk is substantial, Gluck said. "At age 50 a woman has, on average, a 2 percent risk of getting breast cancer, so if she experiences menopausal symptoms the risk is suddenly only 1 percent," he said.

Similarly, an 80-year-old woman has a 14 percent risk of developing breast cancer, Gluck said. If she had menopausal symptoms, her risk is cut to only 7 percent, he noted.

"If you have menopausal symptoms, understand it's a natural process and it might reduce the risk of breast cancer," Gluck said. "So, it is something biologically good."

More information

For more information on breast cancer, visit the American Cancer Society.