Posted on: Wednesday, 26 January 2011, 11:56 CST

The more frequent and severe the hot flushes, the lower the cancer risk

Women who have experienced hot flushes and other symptoms of menopause may have a 50 percent lower risk of developing the most common forms of breast cancer than postmenopausal women who have never had such symptoms, according to a recent study by researchers at Fred Hutchinson Cancer Research Center.

The results of the first study to examine the relationship between menopausal symptoms and breast cancer risk are available online ahead of the February print issue of Cancer Epidemiology Biomarkers and Prevention.

The protective effect appeared to increase along with the number and severity of menopausal symptoms, according to senior author Christopher I. Li, M.D., Ph.D., a breast cancer epidemiologist in the Hutchinson Center’s Public Health Sciences Division.

"In particular we found that women who experienced more intense hot flushes – the kind that woke them up at night – had a particularly low risk of breast cancer," he said.

Li and colleagues suspected a link between menopause misery and decreased breast cancer risk because hormones such as estrogen and progesterone play an important role in the development of most breast cancers, and reductions in these hormones caused by gradual cessation of ovarian function can impact the frequency and severity of menopausal symptoms.

"Since menopausal symptoms occur as hormone levels fluctuate and drop, we hypothesized that women who experienced symptoms such as hot flushes and night sweats – particularly frequent and severe symptoms – might have a lower risk of breast cancer due to decreased estrogen levels," he said.

Indeed, the researchers found a 40 percent to 60 percent reduction in the risk of invasive ductal and invasive lobular carcinoma – the two most common types of breast cancer – among women who experienced hot flushes and other symptoms. the association between such symptoms and decreased cancer risk did not change even after the researchers accounted for other factors known to boost breast cancer risk, such as obesity and use of hormone replacement therapy.

For the study, which was funded by the National Cancer Institute, Li and colleagues interviewed 1,437 postmenopausal Seattle-area women, 988 of whom had been previously diagnosed with breast cancer and 449 of whom had not, who served as a comparison group. the women were surveyed about perimenopausal and menopausal symptoms ranging from hot flushes, night sweats and insomnia to vaginal dryness, irregular or heavy menstrual bleeding, depression and anxiety.

"While menopausal symptoms can certainly have a negative impact on quality of life, our study suggests that there may be a silver lining if the reduction in breast cancer risk is confirmed in future studies," Li said. "If these findings are confirmed, they have the potential to improve our understanding of the causes of breast cancer and improve approaches to preventing this disease."

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a Nepalese U.N. peacekeeper helps a woman to carry a tarp and a kitchen set in February. STORY HIGHLIGHTS

• NEW: French doctor says "massive contamination" of river caused the epidemic
• Epidemiologist’s report suggests Nepalese soldiers may have been the starting point
• United Nations has not dismissed the report, but "not accepted it completely" either
• CDC: "No evidence whatsoever that would suggest" the strain is unique to Nepal

Port-Au-Prince, Haiti (CNN) — a French doctor’s report suggests that the strain of cholera ravaging Haiti may have originated with U.N. peacekeepers from Nepal, but U.N. officials and others cautioned that the report was inconclusive.

The report by French epidemiologist Dr. Renaud Piarroux rules out a number of potential causes and points to the Nepalese soldiers as the most probable, said Vincenzo Pugliese, spokesman for the U.N. mission in Haiti, but it fails to deliver definitive proof.

"we have not dismissed the report but we have not accepted it completely," he said. "we remain open to investigating this and we will get to the bottom of it."

The Centers for Disease Control and Prevention’s Dr. Eric Mintz said research seeking the origin of the deadly outbreak — the death toll has now topped 2,000 since the first case was reported in mid-October — is being undertaken around the world.

"to date, I am aware of no evidence whatsoever that would suggest the strain in Haiti is unique to Nepal," Mintz said. "by the tests we have done here so far, this strain is indistinguishable from strains that have been seen in other countries in South Asia. Vibrio cholerae strains do not get their passports stamped when they cross an international border, and there are many strains in circulation around the globe at any given time."

The first case was reported October 14 in the north of the country, near a camp of Nepalese peacekeepers, but Pugliese said he was unaware that Piarroux had ever visited the camp. more than 90,000 people have been sickened by the water-borne disease, according to Haiti’s Ministry of Public Health.

In his report, Piarroux — who said his investigation lasted from November 7-27 — said the first cases came from residents living near the Artibonite River and that many of the early victims were getting their water from that river or its tributaries, downriver from the U.N. peacekeeper camp.

At one village, Piarroux said, residents told his team of pipes running from the camp to the river and that a nauseating substance flowed through the pipes. the residents said that military people removed the pipes, which they said came from a septic tank in the camp.

Doctors from the U.N. mission tested the latrines at the base on October 21, but the tests were negative for cholera, he said. the doctors told him the tests were conducted while the pipes were open.

"But it’s impossible to know if the septic tank or the pipes had been disinfected before the samples were taken," Piarroux wrote.

Piarroux noted the first cases of cholera were reported just days after a new battalion of soldiers arrived from Kathmandu, Nepal, on October 8 and 12. Kathmandu was experiencing a cholera outbreak at the time, he said, but doctors said none of the soldiers came forward with symptoms and that none of the samples collected from the camp registered positive for cholera.

Piarroux, however, urged caution in accepting those reports and suggested officials could have taken measures to erase any trace of cholera.

While the epidemic began near the camp along the Artibonite tributary, Piarroux wrote, "massive contamination" of the river and its delta caused an explosion of the disease. Cases of the disease follow downriver in succession, he said, notably on October 19, when six communities 100 kilometers away from the initial outbreak — all downriver — experienced outbreaks.

"This massive and widespread contamination across the entire delta and region of the Artibonite could only have been started by dumping a phenomenal amount of fecal material from infected people all at once," he wrote.

And from those areas, he said, infected people carried the disease to other villages, where human-to-human transmission took place.

Haiti was already reeling from the devastating 7.0 magnitude earthquake that hit the island nation on January 12, killing more than 220,000 dead, injuring more than 300,000 and leaving more than 1 million homeless. last month, Hurricane Tomas brushed the island, dumping torrents of rain.

Piarroux’s expert report was submitted to the French Foreign Ministry, which said it had received the report and sent it on to the United Nations and the Haitian government. the Haitian government, however, said it had not seen the study.

Several aid workers said they were concerned about the report’s suggestions, given Haiti’s currently volatile situation and stress that it is inclusive. Pugliese said the publicity surrounding the report was "a point of concern" that more violence against the peacekeepers could erupt as Haiti was already tense amid the pending announcement of election results, expected sometime Tuesday evening.

Stefano Zannini, head of the Haiti mission for Medecins Sans Frontiers (Doctors Without Borders) said the stir over the cholera outbreak’s origins was not as important as the battle against the intestinal disease.

"One person is dying every 30 minutes in Haiti," Zannini said. "Knowing the origin of the epidemic has no impact on saving lives."

CNN’s Moni Basu, Jim Spellman and Miriam Falco contributed to this report.