WASHINGTON - By Will Dunham
Regular exercise can reduce a woman's risk of cancer, but the benefits may slip away if she gets too little sleep, U.S. researchers said on Monday.
The study involving 5,968 women in Maryland confirmed previous findings that people who do regular physical activity are less likely to develop cancer.
But when the researchers looked at the women ages 18 to 65 who were in the upper half in terms of the amount of physical exercise they got per week, they found that sleep appeared to play an important role in cancer risk.
Those who slept less than seven hours nightly had a 47 percent higher risk of cancer than those who got more sleep among the physically active women, the researchers reported at a meeting of the American Association for Cancer Research.
"We think it's quite interesting and intriguing. It's kind of a first look into this. It isn't something that has been widely studied," James McClain of the National Cancer Institute, part of the U.S. government's National Institutes of Health, said in a telephone interview.
McClain, who led the study, said it is unclear exactly how getting too little sleep may make one more susceptible to cancer. "Getting adequate sleep has been long associated with health," McClain said.
The U.S. Centers for Disease Control and Prevention calls sleep loss an under-recognized public health problem, saying Americans are getting less and less slumber. The CDC said the percentage of adults reporting sleeping six hours or fewer a night increased from 1985 to 2006.
Sleep experts say chronic sleep loss is associated with obesity, diabetes, high blood pressure, stroke, cardiovascular disease, depression, cigarette smoking and excessive drinking.
In addition, research had shown that people who get regular exercise have a reduced risk of breast, colon and other types of cancer. Experts think the effects of exercise on the body's hormone levels, immune function and body weight may play an important role.
Copyright 2008 Reuters
Senin, 24 November 2008
Popping vitamins C and E doesn't stop cancer
WASHINGTON - Men who took vitamin E or vitamin C supplements were no more or less likely to develop cancer than men given a placebo, indicating these antioxidants have no cancer-prevention value, U.S. researchers said on Sunday.
Previous research showed that people who ate diets rich in vitamins E and C had a lower risk of cancer, suggesting that supplements of these vitamins might help ward off cancer, the researchers said.
The new study tracked cancer risk in 14,641 male U.S. doctors who took either 400 IU of vitamin E every other day or a placebo, or 500 milligrams of vitamin C daily or a placebo. Their average age was 64 at the start of the study and they were followed for eight years on average.
Taking the vitamins had no impact on the risk for any type of cancer, Howard Sesso of Harvard Medical School and Brigham and Women's Hospital in Boston and colleagues reported at a meeting of the American Association for Cancer Research.
Vitamins don't prevent heart disease, eitherOne week ago, Sesso reported in the Journal of the American Medical Association that in the same population of men, taking these vitamins also failed to reduce their risk of cardiovascular disease including heart attack and stroke.
"In our view, there's really no compelling reason to take these individual vitamin E and C supplements," Sesso said in a telephone interview. "Until other evidence comes out otherwise, we would argue that without any clear benefit, why would you take these?"
Vitamin E and vitamin C are antioxidants, thought to protect against damage caused by free radicals, substances that can harm cells, tissues and organs. Fruits and vegetables are rich in both, and it has been shown that people who eat plenty of these foods may have a lower risk of heart disease, cancer and other conditions.
The researchers were particularly interested in whether vitamin E supplementation would reduce the risk of prostate cancer after earlier research suggested it might. It did not.
There has been controversy over vitamin C and cancer for decades. The idea that vitamin C, also known as ascorbic acid, could be used to treat cancer was advanced in the 1970s by American scientist Linus Pauling, who awarded the Nobel Prize in chemistry in 1954.
Sesso said an ongoing element of his research is looking at whether taking a multivitamin combining a number of different vitamins has any effect on the risk for cancer and cardiovascular disease.
Copyright 2008 Reuters
Previous research showed that people who ate diets rich in vitamins E and C had a lower risk of cancer, suggesting that supplements of these vitamins might help ward off cancer, the researchers said.
The new study tracked cancer risk in 14,641 male U.S. doctors who took either 400 IU of vitamin E every other day or a placebo, or 500 milligrams of vitamin C daily or a placebo. Their average age was 64 at the start of the study and they were followed for eight years on average.
Taking the vitamins had no impact on the risk for any type of cancer, Howard Sesso of Harvard Medical School and Brigham and Women's Hospital in Boston and colleagues reported at a meeting of the American Association for Cancer Research.
Vitamins don't prevent heart disease, eitherOne week ago, Sesso reported in the Journal of the American Medical Association that in the same population of men, taking these vitamins also failed to reduce their risk of cardiovascular disease including heart attack and stroke.
"In our view, there's really no compelling reason to take these individual vitamin E and C supplements," Sesso said in a telephone interview. "Until other evidence comes out otherwise, we would argue that without any clear benefit, why would you take these?"
Vitamin E and vitamin C are antioxidants, thought to protect against damage caused by free radicals, substances that can harm cells, tissues and organs. Fruits and vegetables are rich in both, and it has been shown that people who eat plenty of these foods may have a lower risk of heart disease, cancer and other conditions.
The researchers were particularly interested in whether vitamin E supplementation would reduce the risk of prostate cancer after earlier research suggested it might. It did not.
There has been controversy over vitamin C and cancer for decades. The idea that vitamin C, also known as ascorbic acid, could be used to treat cancer was advanced in the 1970s by American scientist Linus Pauling, who awarded the Nobel Prize in chemistry in 1954.
Sesso said an ongoing element of his research is looking at whether taking a multivitamin combining a number of different vitamins has any effect on the risk for cancer and cardiovascular disease.
Copyright 2008 Reuters
Some breast cancers spontaneously disappear
NEW YORK - The results of a mammographic screening study suggest that some invasive breast cancers may spontaneously regress over time.
These findings "provide new insight on what is arguably the major harm associated with mammographic screening, namely, the detection and treatment of cancers that would otherwise regress," Dr. H. Gilbert Welch, from the Department of Veteran Affairs Medical Center, White River Junction, Vermont, and colleagues state.
The study, which is published in the Archives of Internal Medicine, involved 119,472 women, from 50 to 64 years of age, who underwent three rounds of mammography screening from 1996 to 2001 as part of the Norwegian Breast Cancer Screening Program. The cancer rates in this group were compared with those in 109,784 control women who would have been screened had the program been in place in 1992.
Women in the control group were invited to undergo a one-time screen at the conclusion of their observation period, the authors explain.
As anticipated, the 4-year cumulative incidence of invasive breast cancer in the screened group was higher than in the control group before screening: 1268 vs. 810 cases per 100,000 population.
However, even after the one-time screen in the control group, the 6-year cumulative incidence of breast cancer in the screened group was still higher: 1909 vs. 1564 cases per 100,000 population.
"Because the cumulative incidence among controls never reached that of the screened group, it appears that some breast cancers detected by repeated mammographic screening would not persist to be detectable by a single mammogram at the end of 6 years," Welch and colleagues conclude.
"If the 'spontaneous remission' hypothesis is credible, it should cause a major reevaluation in the approach to breast cancer research and treatment," Dr. Robert M. Kaplan, from University of California, Los Angeles, and Dr. Franz Porzsolt, from the University of Ulm, Germany, write in a related editorial. "Certainly it is worthy of further evaluation. But, finding better data to assess the hypothesis will be difficult."
Copyright 2008 Reuters
(msnbc)
These findings "provide new insight on what is arguably the major harm associated with mammographic screening, namely, the detection and treatment of cancers that would otherwise regress," Dr. H. Gilbert Welch, from the Department of Veteran Affairs Medical Center, White River Junction, Vermont, and colleagues state.
The study, which is published in the Archives of Internal Medicine, involved 119,472 women, from 50 to 64 years of age, who underwent three rounds of mammography screening from 1996 to 2001 as part of the Norwegian Breast Cancer Screening Program. The cancer rates in this group were compared with those in 109,784 control women who would have been screened had the program been in place in 1992.
Women in the control group were invited to undergo a one-time screen at the conclusion of their observation period, the authors explain.
As anticipated, the 4-year cumulative incidence of invasive breast cancer in the screened group was higher than in the control group before screening: 1268 vs. 810 cases per 100,000 population.
However, even after the one-time screen in the control group, the 6-year cumulative incidence of breast cancer in the screened group was still higher: 1909 vs. 1564 cases per 100,000 population.
"Because the cumulative incidence among controls never reached that of the screened group, it appears that some breast cancers detected by repeated mammographic screening would not persist to be detectable by a single mammogram at the end of 6 years," Welch and colleagues conclude.
"If the 'spontaneous remission' hypothesis is credible, it should cause a major reevaluation in the approach to breast cancer research and treatment," Dr. Robert M. Kaplan, from University of California, Los Angeles, and Dr. Franz Porzsolt, from the University of Ulm, Germany, write in a related editorial. "Certainly it is worthy of further evaluation. But, finding better data to assess the hypothesis will be difficult."
Copyright 2008 Reuters
(msnbc)
Langganan:
Postingan (Atom)