(HealthDay News) -- Five years after the results of the Women's Health Initiative sounded the supposed death knell for hormone replacement therapy, experts gathered Wednesday to reassess those results and discuss the fine-tuning and evaluation that has taken place since.
"The science has evolved substantially in the past five years," Dr. JoAnn Manson, chief of the division of preventive medicine at Brigham and Women's Hospital in Boston, said at a press conference sponsored by the Society for Women's Health Research. "There's been mounting evidence that a woman's age and amount of time since onset of menopause may influence the effect of hormone therapy."
The Society for Women's Health Research is a nonprofit organization but has received funds from companies such as Amgen, Cytyc, Eli Lilly, Ethicon and Wyeth.
The original Women's Health Initiative (WHI) was halted when U.S. researchers found an increased risk of adverse events which, depending on whether the woman was taking estrogen alone or estrogen plus progestin, included heart attack, stroke, breast cancer and blood clots.
Manson was one of the principal investigators on the WHI trial.
The average age of women enrolled in the WHI was 63, or about 12 years past menopause.
And the trial was designed not to look at how well hormone therapy combated menopausal symptoms such as hot flashes, but whether it could play a role in chronic disease prevention.
"The WHI was designed to evaluate the balance of benefits and risks of hormone therapy in generally healthy postmenopausal women when used for chronic disease prevention," Manson said. "At the time WHI was started in the early 1990s, it was becoming increasingly common in clinical practice to use hormone therapy in older women who were at high risk of cardiovascular disease, or who already had a diagnosis of cardiovascular disease, in order to prevent future cardiovascular events."
Since then, it has become increasingly clear that hormone therapy has different benefits and risks, depending on the age of the woman.
Just last week, Manson and her colleagues reported in the New England Journal of Medicine that women in their 50s who take estrogen therapy have lower levels of dangerous calcium deposits in their arteries, suggesting they're at reduced risk for heart disease.
But in older women, hormone therapy appears to increase the risk of cardiovascular problems and blood clots, a phenomenon confirmed by a study in this week's British Medical Journal.
And researchers have speculated that a decline in the incidence of breast cancer in recent years is due to a decline in the use of hormone therapy after the WHI results were announced. But a cause-and-effect link is not at all clear.
"I think it's possible that declining use of hormone therapy has contributed at least a little to a decreased incidence rate, but there could be other explanations," Manson said. "There's some suggestion that the decline in breast cancer may have begun as early as 1999, which was well before there was decreasing use of hormone therapy. And there is also some evidence that mammogram screening has decreased over the past several years and that this could contribute to lower rates of detection and diagnosis of breast cancer."
That being said, combined estrogen and progestin has been linked to a risk of breast cancer after four to five years of use. It's not clear if estrogen has a similar risk.
There was some evidence in the WHI study that combination hormone therapy reduced the risk of colon cancer, but the evidence isn't enough to recommend hormones as a preventive strategy, Manson said.
Similarly, while estrogen reduces the risk of fracture and enhances bone density, this benefit would require long-term treatment. Other medications are available and should be tried first, Manson said.
Overall, the bulk of the research today, five years after the WHI, should serve to reassure younger women who may need hormone therapy to alleviate menopausal symptoms.
"The most important reason to go on hormone therapy is for menopausal symptoms," said Dr. Nieca Goldberg, medical director of the Women's Health Program at New York University Medical Center and associate professor of medicine at New York University School of Medicine.
"Younger women who need to go on hormone therapy for this reason can relax. But hormone therapy should never be given to women with cardiovascular disease."
Manson added: "I don't think that hormone therapy should be started or continued for the express purpose of preventing cardiac disease or other chronic diseases, because there are known risks. However, this is very different from the situation in a recently menopausal woman who has moderate to severe hot flashes and night sweats which interfere with sleep and quality of life. Hormone therapy is known to be the most effective treatment for menopausal symptoms.
It's still a very appropriate short-term treatment, but we still recommend using the lowest effective dose for the shortest duration of time necessary."
More information
Visit the U.S. National Library of Medicine for more on hormone replacement therapy.
Kamis, 12 Juli 2007
Selasa, 10 Juli 2007
No Evidence Tomatoes, Lycopene Cut Cancer: FDA
(HealthDay News) -- There's little hard evidence that a diet rich in tomatoes and the tomato antioxidant lycopene can ward off cancer, according to research from the U.S. Food and Drug Administration.
Reporting in the July 10 issue of the Journal of the American Cancer Institute, FDA experts lay out in great detail the evidence -- or mostly lack of it -- behind their November 2005 statement that tomato consumption is not linked to any reduction risk of tumors of the prostate, ovary, stomach and pancreas.
The agency had previously found no evidence that tomatoes could cut risks for lung, colorectal, breast, cervical or endometrial tumors, either.
The November 2005 statement contended that, "there is no credible evidence to support qualified health claims for lycopene, as a food ingredient, component or food, or as a dietary supplement, and reduced risk of any of the cancers in the petition."
The petition for approval of the claims was submitted by a supplement maker, American Longevity.
The FDA has now put the evidence behind its decision in print, said Paul Coates, director of the office of dietary supplements at the U.S. National Institutes of Health and the author of a related journal editorial.
The new data review "gives people some idea of what the process is," Coates said. That's important, he said, because "one of the things that people are concerned about is how are these decisions arrived at. Making the process transparent and open will be helpful."
As part of its review, the FDA pored over data from 107 observational studies comparing the level of consumption of either tomatoes or lycopene with people's general cancer risk.
They also looked at 23 studies that focused on blood levels of lycopene, although most of those trials were deemed unreliable, either because there were too many confounding factors or because most focused on cancer patients, not healthy people.
The agency also included dozens of studies comparing lycopene or tomato intake against the risk of individual cancers such as prostate, colon and breast malignancies.
The bottom line, according to the FDA: There's just not enough evidence to recommend that Americans boost their tomato intake to ward off cancer.
However, the new report is certainly not the last word on cancer-preventing claims for lycopene, Coates added.
"It just codifies the fact that the information about lycopene and cancer is not very robust," he said. "It may well be that if more studies are done, a greater effect might be found. But now, when you look at similar studies done by different people, they come to the same conclusion."
For its part, the American Cancer Society prefers to stay away from recommending any one food as a cancer preventive agent, said Marji McCullough, director of nutritional epidemiology for the organization.
"In our guidelines, we encourage people to eat a variety of foods, especially fruits and vegetables," she said. "Several studies have suggested a lower risk of cancer with some kinds of foods, including tomatoes, but we encourage variety."
The society encourages consumption of "dark deep-colored vegetables, because some studies have found an association between them and lower cancer risk," McCullough said.
The society also encourages fruit and vegetable consumption, because it helps prevent weight gain, she said.
But endorsement of specific foods won't come until research shows that they clearly are associated with lower cancer risk, McCullough said. As for supplements, "most of the evidence comes from studies of foods," she said.
More information
There's more on lycopene at the American Cancer Society.
Reporting in the July 10 issue of the Journal of the American Cancer Institute, FDA experts lay out in great detail the evidence -- or mostly lack of it -- behind their November 2005 statement that tomato consumption is not linked to any reduction risk of tumors of the prostate, ovary, stomach and pancreas.
The agency had previously found no evidence that tomatoes could cut risks for lung, colorectal, breast, cervical or endometrial tumors, either.
The November 2005 statement contended that, "there is no credible evidence to support qualified health claims for lycopene, as a food ingredient, component or food, or as a dietary supplement, and reduced risk of any of the cancers in the petition."
The petition for approval of the claims was submitted by a supplement maker, American Longevity.
The FDA has now put the evidence behind its decision in print, said Paul Coates, director of the office of dietary supplements at the U.S. National Institutes of Health and the author of a related journal editorial.
The new data review "gives people some idea of what the process is," Coates said. That's important, he said, because "one of the things that people are concerned about is how are these decisions arrived at. Making the process transparent and open will be helpful."
As part of its review, the FDA pored over data from 107 observational studies comparing the level of consumption of either tomatoes or lycopene with people's general cancer risk.
They also looked at 23 studies that focused on blood levels of lycopene, although most of those trials were deemed unreliable, either because there were too many confounding factors or because most focused on cancer patients, not healthy people.
The agency also included dozens of studies comparing lycopene or tomato intake against the risk of individual cancers such as prostate, colon and breast malignancies.
The bottom line, according to the FDA: There's just not enough evidence to recommend that Americans boost their tomato intake to ward off cancer.
However, the new report is certainly not the last word on cancer-preventing claims for lycopene, Coates added.
"It just codifies the fact that the information about lycopene and cancer is not very robust," he said. "It may well be that if more studies are done, a greater effect might be found. But now, when you look at similar studies done by different people, they come to the same conclusion."
For its part, the American Cancer Society prefers to stay away from recommending any one food as a cancer preventive agent, said Marji McCullough, director of nutritional epidemiology for the organization.
"In our guidelines, we encourage people to eat a variety of foods, especially fruits and vegetables," she said. "Several studies have suggested a lower risk of cancer with some kinds of foods, including tomatoes, but we encourage variety."
The society encourages consumption of "dark deep-colored vegetables, because some studies have found an association between them and lower cancer risk," McCullough said.
The society also encourages fruit and vegetable consumption, because it helps prevent weight gain, she said.
But endorsement of specific foods won't come until research shows that they clearly are associated with lower cancer risk, McCullough said. As for supplements, "most of the evidence comes from studies of foods," she said.
More information
There's more on lycopene at the American Cancer Society.
Kamis, 05 Juli 2007
Adjusting Cabin Pressure Eases Air Passenger Discomfort
(HealthDay News) -- The discomfort some passengers feel on airplanes could be due to the air pressure settings inside cabins, a new study finds.
Most aircraft cabins are pressurized to 8,000 feet above sea level, an altitude that lowers the amount of oxygen in the blood by about 4 percentage points, researchers say.
This decrease in oxygen saturation isn't enough to bring on acute mountain sickness, but pressurizing the cabin to 6,000 feet could help some passengers feel better when flying, concludes a study in the July 5 issue of the New England Journal of Medicine.
"We found that the altitudes did not affect the occurrence of acute mountain sickness syndrome, but it did affect discomfort," said the study's lead author, Dr. J. Michael Muhm, senior occupation physician for Boeing Commercial Airplanes in Seattle, which funded the study.
"There was no difference in the likelihood of discomfort at ground level and 6,000 feet, but the likelihood increased between 6,000 and 8,000 feet."
He added, "We concluded that passenger and crew comfort would be enhanced" if the cabin was pressurized to 6,000 feet during long-duration flights.
Most commercial aircraft are pressurized to 6,000 to 8,000 feet, not sea level.
"In order to pressurize at ground level, we would have to increase the weight of the aircraft tremendously, because the material as it exists right now couldn't tolerate pressure at ground level," explained Dr. Claude Thibeault, medical director of the International Air Transport Association in Montreal. "We would have to increase fuel, decrease passengers. So, it's an operational sort of factor."
And 8,000 feet, the maximum allowed, is also physiologically acceptable for "normal" people, he added.
"The average Joe in good condition could tolerate 8,000 feet without health effects," Thibeault said. But he noted, "They didn't say without discomfort."
Short-haul flights are usually pressurized at 5,000 to 6,000 feet while long-haul flights are closer to 8,000 feet, according to Thibeault.
But acute mountain sickness, which can involve headache, nausea and vomiting, can occur at altitudes of 6,500 feet and higher.
The authors of the study wanted to see, among other things, if airplane travelers were prone to mountain sickness.
To that end, 502 adult volunteers participated in a 20-hour simulated flight to determine the effect of barometric pressures equivalent to altitudes of 650, 4,000, 6,000, 7,000 and 8,000 feet above sea level on arterial oxygen saturation and the occurrence of acute mountain sickness and discomfort.
Mean oxygen saturation went down as the altitude increased, eventually reaching a maximum decrease of 4.4 percentage points at 8,000 feet.
Acute mountain sickness occurred in 7.4 percent of participants, but the incidence did not vary between the different altitudes.
Discomfort rose with increasing altitude and was greater at 7,000 to 8,000 feet than at all the other altitudes combined. Discomfort became apparent 3 to 9 hours into the "flight."
Older people (over 60) were less likely to report discomfort than younger people, and men seemed more affected than women.
"There were no health effects, but the discomfort was there," Thibeault said. "What they were trying to do in this study is isolate one factor, which is altitude, so you can't blame these effects on other factors."
Next week, Boeing plans to launch its newest aircraft, the 787, with cabins pressurized to 6,000 feet.
"The 787 is one of our first airplanes with the fuselage made out of composites rather than aluminum, a structure that allows us to pressurize to 6,000 feet," said Jeanne Yu, director of environmental performance for Boeing. "The findings of this study, as well as the development of materials technology, enable us to fly the 787."
But she added, changing cabin pressures in existing aircraft is not that simple because of their aluminum structures.
"Airplanes are designed to withstand the continuous pressurization/depressurization cycles that occur in takeoffs and landings throughout their service life. To lower the maximum cruise cabin altitude, the pressure difference must be increased between the interior and exterior of the airplane. This change would fatigue (wear out) the structure more rapidly and impact the airplane's service life in an uncertain way, perhaps even compromising the design integrity of the airplane," she said.
More information
For more on staying healthy when you fly, head to the Academy of Family Physicians.
more discussion: Forum· Addiction Forum · Ask the Doctors Forum · Ayurveda Forum · Ayurvedic & Thai Herbs Forum · Colon Cleansing Forum · Dental Forum · Diabetes Forum · Diet Forum · General Cleansing Forum · Hepatitis A, B. C Forum · Integrated Medicine Forum · Live Blood Analysis Forum · Ozone-Oxygen-Forum · pH - Alkaline - Acidity Forum · Weight Loss Forum
Most aircraft cabins are pressurized to 8,000 feet above sea level, an altitude that lowers the amount of oxygen in the blood by about 4 percentage points, researchers say.
This decrease in oxygen saturation isn't enough to bring on acute mountain sickness, but pressurizing the cabin to 6,000 feet could help some passengers feel better when flying, concludes a study in the July 5 issue of the New England Journal of Medicine.
"We found that the altitudes did not affect the occurrence of acute mountain sickness syndrome, but it did affect discomfort," said the study's lead author, Dr. J. Michael Muhm, senior occupation physician for Boeing Commercial Airplanes in Seattle, which funded the study.
"There was no difference in the likelihood of discomfort at ground level and 6,000 feet, but the likelihood increased between 6,000 and 8,000 feet."
He added, "We concluded that passenger and crew comfort would be enhanced" if the cabin was pressurized to 6,000 feet during long-duration flights.
Most commercial aircraft are pressurized to 6,000 to 8,000 feet, not sea level.
"In order to pressurize at ground level, we would have to increase the weight of the aircraft tremendously, because the material as it exists right now couldn't tolerate pressure at ground level," explained Dr. Claude Thibeault, medical director of the International Air Transport Association in Montreal. "We would have to increase fuel, decrease passengers. So, it's an operational sort of factor."
And 8,000 feet, the maximum allowed, is also physiologically acceptable for "normal" people, he added.
"The average Joe in good condition could tolerate 8,000 feet without health effects," Thibeault said. But he noted, "They didn't say without discomfort."
Short-haul flights are usually pressurized at 5,000 to 6,000 feet while long-haul flights are closer to 8,000 feet, according to Thibeault.
But acute mountain sickness, which can involve headache, nausea and vomiting, can occur at altitudes of 6,500 feet and higher.
The authors of the study wanted to see, among other things, if airplane travelers were prone to mountain sickness.
To that end, 502 adult volunteers participated in a 20-hour simulated flight to determine the effect of barometric pressures equivalent to altitudes of 650, 4,000, 6,000, 7,000 and 8,000 feet above sea level on arterial oxygen saturation and the occurrence of acute mountain sickness and discomfort.
Mean oxygen saturation went down as the altitude increased, eventually reaching a maximum decrease of 4.4 percentage points at 8,000 feet.
Acute mountain sickness occurred in 7.4 percent of participants, but the incidence did not vary between the different altitudes.
Discomfort rose with increasing altitude and was greater at 7,000 to 8,000 feet than at all the other altitudes combined. Discomfort became apparent 3 to 9 hours into the "flight."
Older people (over 60) were less likely to report discomfort than younger people, and men seemed more affected than women.
"There were no health effects, but the discomfort was there," Thibeault said. "What they were trying to do in this study is isolate one factor, which is altitude, so you can't blame these effects on other factors."
Next week, Boeing plans to launch its newest aircraft, the 787, with cabins pressurized to 6,000 feet.
"The 787 is one of our first airplanes with the fuselage made out of composites rather than aluminum, a structure that allows us to pressurize to 6,000 feet," said Jeanne Yu, director of environmental performance for Boeing. "The findings of this study, as well as the development of materials technology, enable us to fly the 787."
But she added, changing cabin pressures in existing aircraft is not that simple because of their aluminum structures.
"Airplanes are designed to withstand the continuous pressurization/depressurization cycles that occur in takeoffs and landings throughout their service life. To lower the maximum cruise cabin altitude, the pressure difference must be increased between the interior and exterior of the airplane. This change would fatigue (wear out) the structure more rapidly and impact the airplane's service life in an uncertain way, perhaps even compromising the design integrity of the airplane," she said.
More information
For more on staying healthy when you fly, head to the Academy of Family Physicians.
more discussion: Forum· Addiction Forum · Ask the Doctors Forum · Ayurveda Forum · Ayurvedic & Thai Herbs Forum · Colon Cleansing Forum · Dental Forum · Diabetes Forum · Diet Forum · General Cleansing Forum · Hepatitis A, B. C Forum · Integrated Medicine Forum · Live Blood Analysis Forum · Ozone-Oxygen-Forum · pH - Alkaline - Acidity Forum · Weight Loss Forum
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