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《英国医生杂志》
Hair dye is unlikely to cause cancer
Millions of women (and men) worldwide dye their hair every few weeks with potentially toxic chemicals. Should they be worried about cancer? Probably not, say researchers from Spain and Canada who recently searched the literature for evidence of a link and drew a blank. They found 79 studies in all, covering a range of cancers, including breast (14 studies), bladder (10 studies), and haematological cancers (40 studies). Hair dye, used a little or a lot, was not convincingly associated with any of them. The only hint of a problem came from 17 case-control studies that included men. When combined, their results suggested a small increased risk of haematological cancer among men who had ever used hair dye (relative risk 1.57, 95% CI 1.33 to1.84), an isolated finding that could simply be due to publication bias or flaws in the studies' methods, say the authors.
Overall, their findings are reassuring but not unexpected. The most carcinogenic chemicals, diaminotoluene and diaminoanisole, were taken out of hair dyes more than 30 years ago, long before any of the studies in this review were done. Modern hair dyes are unlikely to be a serious public health risk, except possibly for people who work with them, such as hairdressers or manufacturers. Studies of occupational exposure were excluded from this review.
JAMA 2005;293: 2516-25
MRI is better than mammography for screening high risk women
Evidence is mounting that contrast enhanced magnetic resonance imaging (MRI) is a better screening tool than mammography for women with a high risk of breast cancer. Two studies, from the Netherlands and Canada, have already reported that MRI is more sensitive in these women. Now a third study, from the UK, finds the same. In this latest study, researchers screened 649 women with a strong family history or a proved genetic predisposition to breast cancer. The women, who were all aged between 35 and 49, had both tests once a year. Of the 35 cancers found, 77% were detected by MRI and 40% by mammography. The two tests together picked up 94% of cancers. Mammography alone was more specific than MRI alone (93% v 81%).
A linked commentary (pp 1747-9) says it's now clear that MRI detects more cancers, at an earlier stage, than mammography in young, high risk women. The question now is whether screening with MRI saves more lives. If survival data from this and other studies show that it does, women, their doctors, and health service providers will have to weigh that survival benefit against the expense of MRI (it costs 10 times more than mammography) and a lower specificity, which means more false positive results, more investigations, yet more cost, and greater stress for screened women.
Lancet 2005;365: 1769-78
Simvastatin is cost effective across broad range of cardiovascular risk
Among people with vascular disease or diabetes, simvastatin helps prevent strokes, heart attacks, and deaths. The costs of these benefits depend largely on the price of the drug and the baseline risk of the person taking it. In an economic analysis using 2001 prices simvastatin looked like good value for money, costing between ￡4500 and ￡31 100 (6540-45 200; $8340-56 950) for each major vascular event prevented. Saving lives cost a bit more—between ￡21 400 and ￡296 300 for each vascular death prevented.
Credit: LANCET
These figures are based on a placebo controlled trial testing 40 mg simvastatin for five years in over 20 000 adults with vascular disease or diabetes. Overall, the costs of hospital admission for vascular events were lower by a fifth in the treatment group. Although the analysis included only hospital costs, not the cost of primary care, outpatient visits, or laboratory monitoring, the authors are confident that simvastatin is cost effective for a broad population of patients with vascular disease, including adults with moderate risk of vascular events (down to 12% over five years) who are excluded in current treatment guidelines. Falling costs since expiry of the manufacturer's patent in May 2003 are likely to make simvastatin look even more attractive. Generic versions are now available in the UK that cost 85% less than proprietary simvastatin.
Lancet 2005;365: 1779-85
Walking the dog may prolong survival after breast cancer
Women may live longer after breast cancer if they walk for just a few hours each week, according to an analysis from a long running study of American nurses. The nurses were recruited in 1976 and have answered questions about health and lifestyle every two years since then. Between 1984 and 1998, stage I, II, or III breast cancer was diagnosed in 2987 members of the cohort. Researchers put these women into five categories according to the amount of exercise they took, then tracked them up to 2002 or death.
Women reporting a level of exercise equivalent to walking 3-5 hours a week had the lowest risk of death from breast cancer (relative risk compared with women walking less than one hour a week 0.5, 95% CI 0.31 to 0.82). All women who did the exercise equivalent of more than one hour's walking each week were less likely to die from breast cancer than women who did less (relative risks 0.8, 0.5, 0.56, and 0.6 for the top four exercise categories from least to most exercise), although exercise seemed to work best for women with hormone responsive cancers. Ten year survival rates for all women were 92% for women who walked for three or more hours a week (or equivalent), 89% for women who walked for one to three hours a week, and 86% for women who walked less than one hour a week.
Millions of women (and men) worldwide dye their hair every few weeks with potentially toxic chemicals. Should they be worried about cancer? Probably not, say researchers from Spain and Canada who recently searched the literature for evidence of a link and drew a blank. They found 79 studies in all, covering a range of cancers, including breast (14 studies), bladder (10 studies), and haematological cancers (40 studies). Hair dye, used a little or a lot, was not convincingly associated with any of them. The only hint of a problem came from 17 case-control studies that included men. When combined, their results suggested a small increased risk of haematological cancer among men who had ever used hair dye (relative risk 1.57, 95% CI 1.33 to1.84), an isolated finding that could simply be due to publication bias or flaws in the studies' methods, say the authors.
Overall, their findings are reassuring but not unexpected. The most carcinogenic chemicals, diaminotoluene and diaminoanisole, were taken out of hair dyes more than 30 years ago, long before any of the studies in this review were done. Modern hair dyes are unlikely to be a serious public health risk, except possibly for people who work with them, such as hairdressers or manufacturers. Studies of occupational exposure were excluded from this review.
JAMA 2005;293: 2516-25
MRI is better than mammography for screening high risk women
Evidence is mounting that contrast enhanced magnetic resonance imaging (MRI) is a better screening tool than mammography for women with a high risk of breast cancer. Two studies, from the Netherlands and Canada, have already reported that MRI is more sensitive in these women. Now a third study, from the UK, finds the same. In this latest study, researchers screened 649 women with a strong family history or a proved genetic predisposition to breast cancer. The women, who were all aged between 35 and 49, had both tests once a year. Of the 35 cancers found, 77% were detected by MRI and 40% by mammography. The two tests together picked up 94% of cancers. Mammography alone was more specific than MRI alone (93% v 81%).
A linked commentary (pp 1747-9) says it's now clear that MRI detects more cancers, at an earlier stage, than mammography in young, high risk women. The question now is whether screening with MRI saves more lives. If survival data from this and other studies show that it does, women, their doctors, and health service providers will have to weigh that survival benefit against the expense of MRI (it costs 10 times more than mammography) and a lower specificity, which means more false positive results, more investigations, yet more cost, and greater stress for screened women.
Lancet 2005;365: 1769-78
Simvastatin is cost effective across broad range of cardiovascular risk
Among people with vascular disease or diabetes, simvastatin helps prevent strokes, heart attacks, and deaths. The costs of these benefits depend largely on the price of the drug and the baseline risk of the person taking it. In an economic analysis using 2001 prices simvastatin looked like good value for money, costing between ￡4500 and ￡31 100 (6540-45 200; $8340-56 950) for each major vascular event prevented. Saving lives cost a bit more—between ￡21 400 and ￡296 300 for each vascular death prevented.
Credit: LANCET
These figures are based on a placebo controlled trial testing 40 mg simvastatin for five years in over 20 000 adults with vascular disease or diabetes. Overall, the costs of hospital admission for vascular events were lower by a fifth in the treatment group. Although the analysis included only hospital costs, not the cost of primary care, outpatient visits, or laboratory monitoring, the authors are confident that simvastatin is cost effective for a broad population of patients with vascular disease, including adults with moderate risk of vascular events (down to 12% over five years) who are excluded in current treatment guidelines. Falling costs since expiry of the manufacturer's patent in May 2003 are likely to make simvastatin look even more attractive. Generic versions are now available in the UK that cost 85% less than proprietary simvastatin.
Lancet 2005;365: 1779-85
Walking the dog may prolong survival after breast cancer
Women may live longer after breast cancer if they walk for just a few hours each week, according to an analysis from a long running study of American nurses. The nurses were recruited in 1976 and have answered questions about health and lifestyle every two years since then. Between 1984 and 1998, stage I, II, or III breast cancer was diagnosed in 2987 members of the cohort. Researchers put these women into five categories according to the amount of exercise they took, then tracked them up to 2002 or death.
Women reporting a level of exercise equivalent to walking 3-5 hours a week had the lowest risk of death from breast cancer (relative risk compared with women walking less than one hour a week 0.5, 95% CI 0.31 to 0.82). All women who did the exercise equivalent of more than one hour's walking each week were less likely to die from breast cancer than women who did less (relative risks 0.8, 0.5, 0.56, and 0.6 for the top four exercise categories from least to most exercise), although exercise seemed to work best for women with hormone responsive cancers. Ten year survival rates for all women were 92% for women who walked for three or more hours a week (or equivalent), 89% for women who walked for one to three hours a week, and 86% for women who walked less than one hour a week.