THURSDAY, May 15 (HealthDay News) -- An injection of a local anesthetic into the nerves of the neck that regulate temperature could give breast cancer patients long-term relief from hot flashes and sleep deprivation, a new study suggests.

Severe hot flashes often accompany treatment for breast cancer, especially among women taking anti-estrogen drugs. These hot flashes can become so severe that women stop taking their medication at the risk of the cancer returning. In fact, more than 50 percent of these women stop taking their medication after 180 days, researchers report.

"Breast cancer survivors can have very severe hot flashes, and this modality of treatment seems to resolve that without the usual problems of hormone treatments," said lead researcher Dr. Eugene Lipov, medical director at Advanced Pain Centers in Hoffman Estates, Ill.

In the future, this could be how all hot flashes are treated, Lipov said. "Fifty million older women in the United States have hot flashes, not just breast cancer survivors, but menopausal women," he said. "Five million of these women have severe hot flashes."

The current treatments for hot flashes, including estrogen, all have dangers associated with them or are ineffective, Lipov said. "This is a safe approach that works very quickly and can last for up to three years," he said. "The average response time is three to eight months."

The report is published in the June issue of The Lancet Oncology.

In the study, Lipov's team treated 13 breast cancer survivors who had severe hot flashes, using a stellate-ganglion block. The researchers evaluated the number of hot flashes and the quality of the women's sleep one week before the injection and every week thereafter for 12 weeks.

The researchers found that the total number of hot flashes dropped from an average of 79.4 per week before the injection to an average of 49.9 per week in the first two weeks after treatment.

The number of hot flashes continued to decline over 12 weeks and reached a mean of 8.1 hot flashes per week. Moreover, the number of very severe hot flashes dropped to near zero by the end of the 12th week, according to the report.

In addition, the number of night awakenings dropped from an average of 19.5 per week before the injection to an average of 7.3 per week in the first two weeks after the procedure. Night awakenings continued to decrease, to an average of 1.4 per week by the end of the study.

"This is a big advance in treatment for women," Lipov said. "Women with severe hot flashes should really be treated with this."

One expert thinks that this might be a good way of controlling a serious side effect in breast cancer treatment.

"Most women experience hot flashes," said Dr. Joanne Mortimer, vice chairwoman of medical oncology at the City of Hope Comprehensive Cancer Center in Duarte, Calif. "And they interfere with normal activity in 15 percent."

"In addition, 65 percent of women treated for breast cancer experience hot flashes, and we cannot use estrogen replacement in these folks," Mortimer said. "Relief of symptoms is important for all women but is especially a need in the breast cancer survivor population."

Another expert was cautious about the benefits of this treatment and said more data was needed before it could become widely accepted.

"While it looks like the study produced meaningful results for many of the women in the trial, this is a tiny study, which did not go on for very long," said Barbara A. Brenner, executive director of Breast Cancer Action.

Brenner added that because the procedure involves injections and the use of fluoroscopy, which is radiation, it could increase the risk of cancer among women who have had radiation therapy for breast cancer.

"All of which is to say that, while some women will be so seriously affected by hot flashes and disruptions of sleep to want to do this, it would be good to have considerably more data both in terms of numbers studied and long-term side effects before touting it," Brenner said.

More information

For more on hot flashes, visit the U.S. National Library of Medicine.