From Medscape Medical News
Emma Hitt, PhD
July 30, 2009 (Atlanta, Georgia) — New H1N1 influenza vaccine recommendations from the Centers for Disease Control and Prevention (CDC) suggest priority distribution among 5 groups.
Recommended Target Groups
Anne Schuchat, MD, director of the National Center for Immunization and Respiratory Diseases with the CDC, announced that the Advisory Committee of Immunization Practices recommends that 5 target groups receive the vaccine:
•Pregnant women,
•household contacts of children who are younger than 6 months of age,
•healthcare workers and emergency medical services personnel,
•children and young people between the ages of 6 months and 24 years of age, and
•nonelderly adults with underlying risk conditions or medical conditions that increase their risk for complications from influenza.
The committee also addressed the issue of what to do in the event of a vaccine shortage and how to prioritize those groups who should receive the vaccine.
"In general, under most circumstances, we really ought to promote vaccine in all of these 5 focus groups, and...picking them or prioritizing some before others would not benefit the public," Dr. Schuchat said. The CDC's estimate of the target groups totals 159 million individuals, but "there's a lot of overlap in some of the groups...[it is] probably a lower number than that," she said.
"Just in Case" Prioritization Group
However, the Advisory Committee of Immunization Practices also proposed a priority group consisting of a much smaller group, about 41 million individuals, that should be vaccinated in the event of a shortage. These include
•Pregnant women,
•household contacts of children who are younger than 6 months of age,
•healthcare workers and emergency services personnel who have direct patient contact or direct contact with infectious substances,
•children between the ages of 6 months and 4 years of age, and
•children 5 to18 years of age who have underlying risk factors that put them at greater risk for complications of influenza.
According to Dr. Schuchat, the real operating assumption is that they will "go forward with the broader group," she said.
Seasonal Influenza Vaccine Remains Important
According to the CDC, the seasonal influenza vaccine remains very important. "Our assumption is that it is very likely [that seasonal influenza and H1N1 vaccines] can be given together," Dr. Schuchat told Medscape Infectious Diseases during the briefing. "There will be more data coming out...but it is likely they can be given at the same visit," she said. According to Dr. Schuchat, 2 doses of the vaccine will probably be needed, with 15 μg antigen/dose.
"The recommendations make sense on the basis of what we know about this virus," said John Bartlett, MD, chief of the Johns Hopkins University School of Medicine, Division of Infectious Diseases, Baltimore, Maryland.
"Of interest is the observation that persons over 64 years, a high priority for seasonal flu vaccine, are not included here," he told Medscape Infectious Diseases. "That decision is based on the curious observation that the people born before 1957 appear to be relatively well protected from infection or serious disease with this strain of H1N1 virus." According to Dr. Bartlett, it appears that a similar strain circulated before 1957, accounting for this protection; other comparable viruses also have circulated more recently.
"Pregnant women and young people seem to be especially susceptible to [the H1N1] influenza strain and also to bad outcomes when infected," he said. "But the elderly should get [the] seasonal flu vaccine, since they account for the vast majority of the 36,000 deaths attributed to seasonal influenza in the average season" he added. "In fact, most people should get seasonal flu vaccine. The current indications for that vaccine apply to about 80% of the US population."
Production a Concern
Dr. Schuchat noted that the production of the H1N1 vaccine could be unpredictable. "Right now, we are to on track, expecting vaccine doses in the fall," she said, adding that "exactly how many [doses will be available] exactly when will be tough to pinpoint."
"Production is a concern, since the novel H1N1 virus does not grow well in eggs, and 2 doses are likely to be necessary," said Dr. Bartlett. If the virus thrives in the fall in the Northern hemisphere, "it will be a challenge to be ready," he said.
Friday, July 31, 2009
Monday, July 27, 2009
Salt a Key Player in Resistant Hypertension
by Lisa Nainggolan
From Heartwire
July 21, 2009 (Brisbane, Australia) — The first study to evaluate the effects of a low-salt diet in patients with resistant hypertension has shown that this strategy reduced blood pressure far beyond expectations, suggesting that such patients are extremely sensitive to the BP-lowering effects of sodium reduction.
The findings indicate "that in patients with resistant hypertension, a low-salt diet may be more effective than increasing the number of antihypertensive medications," lead author Dr Eduardo Pimenta (Princess Alexandra Hospital, Brisbane, Australia) told heartwire .
As a result, patients with resistant hypertension should, if possible, be counselled by a dietician, and "as 75% of sodium comes from prepared foods, restaurant meals, etc, public-health strategies are needed to reduce sodium content."
In an accompanying editorial commentary [2], Dr Lawrence J Appel (Johns Hopkins University, Baltimore, MD) congratulates Pimenta and coauthors on the implementation of a "challenging but informative and likely influential study" that demonstrated "striking" results. However, the study was small--with only 12 participants--and there was only one week per feeding period, so "replication of the study is clearly warranted," says Appel.
Nevertheless, the research indicates that a "renewed and aggressive emphasis on lifestyle modification, specifically sodium reduction, is warranted in patients with resistant hypertension and uncontrolled BP," he states.
Logistical Difficulties Overcome
Pimenta explains that resistant hypertension--defined as patients with uncontrolled BP despite taking three or more medications--is a common problem, affecting an estimated 20% to 30% of those with hypertension, and its prevalence is increasing.
The effects of reducing dietary sodium on mild-to-moderate hypertension are well documented, and have shown a small BP reduction with a low-salt diet, he adds. But according to Pimenta there have been no previous studies evaluating the role of dietary salt in those with resistant hypertension.
He and his colleagues conducted a two-period, randomized, crossover feeding study that compared two levels of sodium intake--250 mmol (5700 mg) per day versus 50 mmol (1150 mg) per day--in 12 patients with resistant hypertension referred to the University of Alabama Hypertension Clinic, where Pimenta was a postdoctoral research fellow. The aim was to determine the effects of dietary sodium restriction on office and 24-hour ambulatory BP, and each feeding period lasted one week.
At baseline, the participants–-half of whom were black and 67% of whom were female--had a mean body mass index of 32.9 kg/m2 and a mean office BP of 145.8/83.9 mm Hg on an average of 3.4 antihypertensive medications.
Results Extend the Role of Sodium Reduction to Resistant Hypertension
Compared with the higher level of sodium intake, the lower level reduced mean office systolic BP by 22.7 mm Hg and office diastolic BP by 9.1 mm Hg. Reductions in daytime, nighttime, and 24-hour ambulatory BP were virtually identical to reductions in office BP.
Importantly, says Appel, "the extent of BP reduction vastly exceeds corresponding levels of BP reduction observed in [salt-reducing] trials of hypertensive individuals not on medication," for example, the participants with untreated hypertension in the Dietary Approaches to Stop Hypertension (DASH)-sodium study.
"In the context of other human research on dietary sodium intake and BP, which has focused almost exclusively on individuals who were on no or few antihypertensive medications, these results extend the role of sodium reduction to an important but understudied population," he states.
And he admits to being "surprised by the extent of the BP reduction," which he describes as "huge . . . roughly equivalent to adding two antihypertensive medications."
HCTZ Not the Best Choice of Diuretic for Resistant Hypertension
All of the participants were taking the diuretic hydrochlorothiazide (HCTZ), and both Appel and Pimenta say that in this setting, one might have expected an attenuated effect from dietary salt reduction, given that the patients were already on volume-reducing therapy.
But the pattern of findings suggests a volume-expanded state on conventional doses of HCTZ, indicating that the diuretic type and dose recommended by general hypertension guidelines "may not be as effective in patients with resistant hypertension [as in] mild-to-moderate hypertensives," Pimenta says.
He suggests that chlorthalidone, "which reduces BP more effectively and has a longer duration of action than HCTZ," should be used in resistant hypertension patients, and Appel concurs.
A Clear Target for Intervention
"Another remarkable, perhaps expected, finding was the high baseline sodium intake" of the participants, "measured when [they] were eating food that they prepared or selected," notes Appel. The mean 24-hour dietary sodium excretion at baseline--194.7 mmol (4470 mg) per day--was nearly double the recommended upper limit of daily sodium for the general population, and nearly triple the corresponding daily limit for people with hypertension, he observes.
"Although one might be discouraged by the excessive levels of sodium intake in this high-risk population, such levels also provide a clear opportunity for intervention," he stresses. But a "critical issue" is how to accomplish this. A combination of individual-based counselling (eg, from a dietician) and public-health strategies to reduce the sodium content of the food supply at a population level are needed, he believes.
"It will be impossible to reach an intake of 50 mmol per day without a major reduction in the sodium content of commercially prepared foods. Outside the arcane environment of the feeding study, a sodium intake of around 50 mmol per day is rare in the US," where, even with intensive behavioral counselling focusing exclusively on sodium reduction, mean achieved levels of sodium intake are typically about 100 mmol (2300 mg) per day, he observes.
In the meantime, doctors managing patients with resistant hypertension should use chlorthalidone rather than HCTZ, should reinforce key messages related to the reduction of dietary sodium intake, and should refer the patient, if possible, to a dietician. In addition, physicians need to "advocate for policy changes that lead to a reduced sodium content of commercially prepared foods," Appel concludes.
From Heartwire
July 21, 2009 (Brisbane, Australia) — The first study to evaluate the effects of a low-salt diet in patients with resistant hypertension has shown that this strategy reduced blood pressure far beyond expectations, suggesting that such patients are extremely sensitive to the BP-lowering effects of sodium reduction.
The findings indicate "that in patients with resistant hypertension, a low-salt diet may be more effective than increasing the number of antihypertensive medications," lead author Dr Eduardo Pimenta (Princess Alexandra Hospital, Brisbane, Australia) told heartwire .
As a result, patients with resistant hypertension should, if possible, be counselled by a dietician, and "as 75% of sodium comes from prepared foods, restaurant meals, etc, public-health strategies are needed to reduce sodium content."
In an accompanying editorial commentary [2], Dr Lawrence J Appel (Johns Hopkins University, Baltimore, MD) congratulates Pimenta and coauthors on the implementation of a "challenging but informative and likely influential study" that demonstrated "striking" results. However, the study was small--with only 12 participants--and there was only one week per feeding period, so "replication of the study is clearly warranted," says Appel.
Nevertheless, the research indicates that a "renewed and aggressive emphasis on lifestyle modification, specifically sodium reduction, is warranted in patients with resistant hypertension and uncontrolled BP," he states.
Logistical Difficulties Overcome
Pimenta explains that resistant hypertension--defined as patients with uncontrolled BP despite taking three or more medications--is a common problem, affecting an estimated 20% to 30% of those with hypertension, and its prevalence is increasing.
The effects of reducing dietary sodium on mild-to-moderate hypertension are well documented, and have shown a small BP reduction with a low-salt diet, he adds. But according to Pimenta there have been no previous studies evaluating the role of dietary salt in those with resistant hypertension.
He and his colleagues conducted a two-period, randomized, crossover feeding study that compared two levels of sodium intake--250 mmol (5700 mg) per day versus 50 mmol (1150 mg) per day--in 12 patients with resistant hypertension referred to the University of Alabama Hypertension Clinic, where Pimenta was a postdoctoral research fellow. The aim was to determine the effects of dietary sodium restriction on office and 24-hour ambulatory BP, and each feeding period lasted one week.
At baseline, the participants–-half of whom were black and 67% of whom were female--had a mean body mass index of 32.9 kg/m2 and a mean office BP of 145.8/83.9 mm Hg on an average of 3.4 antihypertensive medications.
Results Extend the Role of Sodium Reduction to Resistant Hypertension
Compared with the higher level of sodium intake, the lower level reduced mean office systolic BP by 22.7 mm Hg and office diastolic BP by 9.1 mm Hg. Reductions in daytime, nighttime, and 24-hour ambulatory BP were virtually identical to reductions in office BP.
Importantly, says Appel, "the extent of BP reduction vastly exceeds corresponding levels of BP reduction observed in [salt-reducing] trials of hypertensive individuals not on medication," for example, the participants with untreated hypertension in the Dietary Approaches to Stop Hypertension (DASH)-sodium study.
"In the context of other human research on dietary sodium intake and BP, which has focused almost exclusively on individuals who were on no or few antihypertensive medications, these results extend the role of sodium reduction to an important but understudied population," he states.
And he admits to being "surprised by the extent of the BP reduction," which he describes as "huge . . . roughly equivalent to adding two antihypertensive medications."
HCTZ Not the Best Choice of Diuretic for Resistant Hypertension
All of the participants were taking the diuretic hydrochlorothiazide (HCTZ), and both Appel and Pimenta say that in this setting, one might have expected an attenuated effect from dietary salt reduction, given that the patients were already on volume-reducing therapy.
But the pattern of findings suggests a volume-expanded state on conventional doses of HCTZ, indicating that the diuretic type and dose recommended by general hypertension guidelines "may not be as effective in patients with resistant hypertension [as in] mild-to-moderate hypertensives," Pimenta says.
He suggests that chlorthalidone, "which reduces BP more effectively and has a longer duration of action than HCTZ," should be used in resistant hypertension patients, and Appel concurs.
A Clear Target for Intervention
"Another remarkable, perhaps expected, finding was the high baseline sodium intake" of the participants, "measured when [they] were eating food that they prepared or selected," notes Appel. The mean 24-hour dietary sodium excretion at baseline--194.7 mmol (4470 mg) per day--was nearly double the recommended upper limit of daily sodium for the general population, and nearly triple the corresponding daily limit for people with hypertension, he observes.
"Although one might be discouraged by the excessive levels of sodium intake in this high-risk population, such levels also provide a clear opportunity for intervention," he stresses. But a "critical issue" is how to accomplish this. A combination of individual-based counselling (eg, from a dietician) and public-health strategies to reduce the sodium content of the food supply at a population level are needed, he believes.
"It will be impossible to reach an intake of 50 mmol per day without a major reduction in the sodium content of commercially prepared foods. Outside the arcane environment of the feeding study, a sodium intake of around 50 mmol per day is rare in the US," where, even with intensive behavioral counselling focusing exclusively on sodium reduction, mean achieved levels of sodium intake are typically about 100 mmol (2300 mg) per day, he observes.
In the meantime, doctors managing patients with resistant hypertension should use chlorthalidone rather than HCTZ, should reinforce key messages related to the reduction of dietary sodium intake, and should refer the patient, if possible, to a dietician. In addition, physicians need to "advocate for policy changes that lead to a reduced sodium content of commercially prepared foods," Appel concludes.
Pesticide Exposure Linked to Parkinson's, Alzheimer's Disease
Pauline Anderson
From Medscape Medical News
July 23, 2009 — Two new studies have added to the growing body of evidence pointing to a link between pesticide exposure and the risk for neurological disorders.
One study linked high levels of an organochlorine pesticide called beta-hexachlorocyclohexane (beta-HCH) to an increased risk for Parkinson's disease (PD), while another showed an association between agricultural pesticide exposure and dementia, including Alzheimer's disease (AD).
The first study, published in the July issue of Archives of Neurology, included 50 patients with PD treated at the Clinical Center for Movement Disorders at the University of Texas (UT) Southwestern Medical Center at Dallas and 20 patients with AD and 43 controls from the Alzheimer's Disease Center at the UT Southwestern Medical Center.
Using blood samples, researchers tested for 16 organochlorine pesticides, including beta-HCH. The specific pesticides included in the study were chosen on the basis of how often they show up in environmental samples.
Banned During the 1970s
Used extensively across the United States beginning in the 1950s, organochlorine pesticides were banned during the 1970s because of concerns about their bioaccumulation and toxic effects. Animal studies show that these pesticides are neurotoxic, cause oxidative stress, and damage the brain's dopaminergic system.
The study, 1 of the largest of its kind to date and perhaps the first to link a particular pesticide with PD, found that 9 of the 16 pesticides tested were present in study subjects. The pesticide found most often was p.pDDE. It was detected in 100% of the AD patients, 72% of the PD patients, and 86% of the controls.
Beta-HCH was also present in elevated levels in some patients. It was detected most often in the serum of patients with PD: 38 of 50 (76%) compared with 17 of 43 (40%) in controls and 6 of 20 (30%) in patients with AD.
Compared with controls, the odds ratio for PD risk associated with beta-HCH levels was 4.39. The median level of beta-HCH was significantly higher in patients with PD (median, 0.36 ng/mL) compared with controls and patients with AD (median, 0 ng/mL for both).
This pesticide was widely used during the 1960s and 1970s, particularly on cotton plants, said Dr. Richardson. Although banned as a pesticide more than 30 years ago, traces of beta-HCH can still be found in water and soil.
Factors That Alter Risk
Researchers found beta-HCH in samples of some controls, although generally at lower levels than in patients with PD. This, said Dr. Richardson, suggests that other factors may interact with beta-HCH exposure to alter the risk for PD. While caffeine consumption and cigarette smoking have been associated with a decreased risk for PD, Dr. Richardson said it is most likely genetic factors that determine risk.
Blood samples from 18 of the PD patients taken 5 years apart showed that mean levels of beta-HCH did not change significantly over time. "This suggested that there may be some people who, because of their genetics, may not get rid of this pesticide as well as others, and these people may be the ones who are at risk for Parkinson's," said Dr. Richardson. "That's something we're very interested in trying to determine."
The authors noted that since 12 PD patients did not have detectable levels of beta-HCH, exposure to this pesticide may contribute to PD in only a subset of patients.
Exposure Through Food
Dr. Richardson speculated that most of the pesticide exposure is through food consumption. He noted that other studies have found a high rate of PD among populations that consume large quantities of fish and whale meat.
The second study, presented earlier this month at the Alzheimer's Association 2009 International Conference on Alzheimer's Disease (ICAD 2009), in Vienna, Austria, was part of a longitudinal cohort study of memory in aging among residents of Cache County, Utah, aged 65 years and older. These residents were asked detailed questions about their pesticide exposure.
Of 4012 study participants who had no dementia at baseline in 1995, 743 reported some exposure to pesticides, said Kathleen M. Hayden, PhD, assistant professor of psychiatry and behavioral sciences at Duke University, in Durham, North Carolina, who presented the findings.
Pesticides Only 1 Piece of Dementia Puzzle
Unlike patients in the first study, most of the exposure to pesticides in this analysis was likely through farming. Cache County is 1 of the primary agricultural regions in Utah, leading the state in barley production, said Dr. Hayden. Pesticide exposure of some study participants extended to 12 or more years.
Over 7 years of follow-up, 412 patients were identified with incident dementia, most with AD. Of these, 85 had reported exposure to pesticides.
After adjusting for age, sex, education, and APOE genotype, researchers determined that residents exposed to pesticides had an increased risk for dementia (OR, 1.56; 95% CI, 1.16 – 2.09). The OR for AD was 1.53 (95% CI, 1.02 – 2.26).
Although the study was not ideal (exposure classifications were less than perfect, for example), its strengths were that it had a relatively large sample size, the residents were followed for several years, and they underwent regular diagnostic assessments, said Dr. Hayden.
"It's definitely not a definitive study, but it does add to a growing body of literature linking pesticides to dementia," she said.
Pesticide exposure is likely only 1 piece of the AD puzzle. "Pesticides represent only 1 environmental factor; there are many environmental factors that may increase risk, and some that decrease risk," said Dr. Hayden. "These probably combine with genetic risk factors that we know about and others we have yet to discover."
Arch Neurol. 2009;66:870-875. Abstract
From Medscape Medical News
July 23, 2009 — Two new studies have added to the growing body of evidence pointing to a link between pesticide exposure and the risk for neurological disorders.
One study linked high levels of an organochlorine pesticide called beta-hexachlorocyclohexane (beta-HCH) to an increased risk for Parkinson's disease (PD), while another showed an association between agricultural pesticide exposure and dementia, including Alzheimer's disease (AD).
The first study, published in the July issue of Archives of Neurology, included 50 patients with PD treated at the Clinical Center for Movement Disorders at the University of Texas (UT) Southwestern Medical Center at Dallas and 20 patients with AD and 43 controls from the Alzheimer's Disease Center at the UT Southwestern Medical Center.
Using blood samples, researchers tested for 16 organochlorine pesticides, including beta-HCH. The specific pesticides included in the study were chosen on the basis of how often they show up in environmental samples.
Banned During the 1970s
Used extensively across the United States beginning in the 1950s, organochlorine pesticides were banned during the 1970s because of concerns about their bioaccumulation and toxic effects. Animal studies show that these pesticides are neurotoxic, cause oxidative stress, and damage the brain's dopaminergic system.
The study, 1 of the largest of its kind to date and perhaps the first to link a particular pesticide with PD, found that 9 of the 16 pesticides tested were present in study subjects. The pesticide found most often was p.pDDE. It was detected in 100% of the AD patients, 72% of the PD patients, and 86% of the controls.
Beta-HCH was also present in elevated levels in some patients. It was detected most often in the serum of patients with PD: 38 of 50 (76%) compared with 17 of 43 (40%) in controls and 6 of 20 (30%) in patients with AD.
Compared with controls, the odds ratio for PD risk associated with beta-HCH levels was 4.39. The median level of beta-HCH was significantly higher in patients with PD (median, 0.36 ng/mL) compared with controls and patients with AD (median, 0 ng/mL for both).
This pesticide was widely used during the 1960s and 1970s, particularly on cotton plants, said Dr. Richardson. Although banned as a pesticide more than 30 years ago, traces of beta-HCH can still be found in water and soil.
Factors That Alter Risk
Researchers found beta-HCH in samples of some controls, although generally at lower levels than in patients with PD. This, said Dr. Richardson, suggests that other factors may interact with beta-HCH exposure to alter the risk for PD. While caffeine consumption and cigarette smoking have been associated with a decreased risk for PD, Dr. Richardson said it is most likely genetic factors that determine risk.
Blood samples from 18 of the PD patients taken 5 years apart showed that mean levels of beta-HCH did not change significantly over time. "This suggested that there may be some people who, because of their genetics, may not get rid of this pesticide as well as others, and these people may be the ones who are at risk for Parkinson's," said Dr. Richardson. "That's something we're very interested in trying to determine."
The authors noted that since 12 PD patients did not have detectable levels of beta-HCH, exposure to this pesticide may contribute to PD in only a subset of patients.
Exposure Through Food
Dr. Richardson speculated that most of the pesticide exposure is through food consumption. He noted that other studies have found a high rate of PD among populations that consume large quantities of fish and whale meat.
The second study, presented earlier this month at the Alzheimer's Association 2009 International Conference on Alzheimer's Disease (ICAD 2009), in Vienna, Austria, was part of a longitudinal cohort study of memory in aging among residents of Cache County, Utah, aged 65 years and older. These residents were asked detailed questions about their pesticide exposure.
Of 4012 study participants who had no dementia at baseline in 1995, 743 reported some exposure to pesticides, said Kathleen M. Hayden, PhD, assistant professor of psychiatry and behavioral sciences at Duke University, in Durham, North Carolina, who presented the findings.
Pesticides Only 1 Piece of Dementia Puzzle
Unlike patients in the first study, most of the exposure to pesticides in this analysis was likely through farming. Cache County is 1 of the primary agricultural regions in Utah, leading the state in barley production, said Dr. Hayden. Pesticide exposure of some study participants extended to 12 or more years.
Over 7 years of follow-up, 412 patients were identified with incident dementia, most with AD. Of these, 85 had reported exposure to pesticides.
After adjusting for age, sex, education, and APOE genotype, researchers determined that residents exposed to pesticides had an increased risk for dementia (OR, 1.56; 95% CI, 1.16 – 2.09). The OR for AD was 1.53 (95% CI, 1.02 – 2.26).
Although the study was not ideal (exposure classifications were less than perfect, for example), its strengths were that it had a relatively large sample size, the residents were followed for several years, and they underwent regular diagnostic assessments, said Dr. Hayden.
"It's definitely not a definitive study, but it does add to a growing body of literature linking pesticides to dementia," she said.
Pesticide exposure is likely only 1 piece of the AD puzzle. "Pesticides represent only 1 environmental factor; there are many environmental factors that may increase risk, and some that decrease risk," said Dr. Hayden. "These probably combine with genetic risk factors that we know about and others we have yet to discover."
Arch Neurol. 2009;66:870-875. Abstract
Friday, July 17, 2009
1 in 3 Breast Cancers Detected by Screening Is Overdiagnosed, Overtreated
From Medscape Medical News
by Nick Mulcahy
July 14, 2009 — One in 3 breast cancers detected in publicly organized screening programs is overdiagnosed. And overtreatment inevitably occurs at the same rate, according to a meta-analysis of screening programs in Canada, Australia, Norway, Sweden, and the United Kingdom, published online July 9 in BMJ.
The new analysis is yet another study that adds to the controversy surrounding mammography's benefits and harms, which include overdiagnosis and overtreatment.
"The question is no longer whether overdiagnosis occurs, but how often it occurs," writes Gilbert Welch, MD, in an editorial accompanying the newly published analysis.
Overdiagnosis of cancer refers to cancers that grow so slowly that the patient dies of other causes before it produces symptoms or to cancer that is dormant or even regresses, explained Dr. Welch, who is a professor of medicine at Dartmouth Medical School in Hanover, New Hampshire.
Overdiagnosis is a "widely recognized problem" in prostate cancer screening, said Dr. Welch.
With regard to breast cancer, there is a growing body of evidence about overdiagnosis with which the new study is consistent, he added.
Namely, there are now 5 observational studies that indicate screening mammography is associated with increases in the incidence of breast cancer in women of screening age, but that there is "little or no subsequent decrease in the incidence of older women," notes Dr. Welch.
But is the rate of overdiagnosis really as high as 1 in 3 screen-detected cancers?
Dr. Welch says that that the "most compelling evidence to date" about overdiagnosis comes from an earlier randomized controlled trial of mammography versus observation (BMJ. 2006;332:689-692). In that study, overdiagnosis from screening occurred at a rate of 1 in 6, Dr. Welch notes.
Whatever the rate of overdiagnosis, both the study authors and the editorialist agree, overtreatment is likely to occur at the same rate.
"As it is not possible to distinguish between lethal and harmless cancers, all detected cancers are treated," write the study authors, Karsten Juhl Jørgensen, MD, and Peter C Gøtzsche, MD, from the Nordic Cochrane Center in Copenhagen, Denmark.
Close Call
The balance between the benefits and harms of mammography make it one of medicine's "close calls," adds Dr. Welch. It is a close call that has received a lot of public attention in the past year.
In the United Kingdom, there was public outcry over the lack of information about the harms of mammography in a public-health pamphlet about breast cancer screening. The protest led to a rewrite of the pamphlet, as reported by Medscape Oncology.
Furthermore, The New York Times and other media made front-page news out of a 2008 study from Norway that concluded that about 20% of screen-detected invasive breast cancers spontaneously regress. One of the Norwegian researchers told Medscape Oncology that such lesions are "pseudo-cancers."
In making decisions about whether or not to get screened, women are probably most interested in the "trade-off between the number of deaths from breast cancer avoided and the number of cancers overdiagnosed," suggested Dr. Welsh.
In an effort to provide physicians and their patients with a "balance sheet" of the harms and benefits of mammography, Dr. Welch included a tabular display along with his editorial. The credits and debits are for every 1000 women undergoing annual mammography for 10 years starting at the age of 50 years.
Credits :1 woman will avoid dying from breast cancer
Debits : 2–10 women will be overdiagnosed and treated needlessly
Credit: 10–15 women will be told they have breast cancer earlier than they would otherwise have been told, but this will not affect their prognosis
debit: 100–500 women will have at least 1 "false alarm" (about half these women will undergo biopsy)
New Study Details
To estimate the extent of overdiagnosis in organized screening programs, the Danish investigators compared trends in breast cancer incidence before and after the screening was initiated in the United Kingdom; Manitoba, Canada; New South Wales, Australia; Sweden; and parts of Norway.
The reason for this approach is based on the idea that, if screening was effective and did not produce overdiagnosis, then "the initial increase in cancers in the screened age groups would be fully compensated for by a similar decrease in the older age groups no longer offered screening," write the authors. Why is this so? Because the cancers in the older age groups would have been detected earlier on in life, as a result of screening, explain the authors.
The authors also note that such an approach must take into account changes in the background incidence of breast cancer and other factors.
One set of data offers an example of how the analysis was conducted. In Sweden, nationwide screening began in 1986, and in 1998, "almost all eligible women had been offered screening," the authors write. In 2000, the increase in invasive cancer after screening was implemented was 54% above expected rates for women aged 50 to 59 years and 21% for women aged 60 to 69 years. A drop in the incidence of breast cancer occurred among women aged 70 to 84 years, but the incidence "approached the expected rate," write the authors. In short, 88% of the increase among younger women was not compensated for by any drop in the older women, note the authors.
In summary, the total overdiagnosis of breast cancers, including ductal carcinoma in situ, from these public screening programs in different countries was 52%. The overdiagnosis of invasive breast cancer was 35%, report the authors.
BMJ. 2009;339:b1425 and b2587. Abstract, Abstract
by Nick Mulcahy
July 14, 2009 — One in 3 breast cancers detected in publicly organized screening programs is overdiagnosed. And overtreatment inevitably occurs at the same rate, according to a meta-analysis of screening programs in Canada, Australia, Norway, Sweden, and the United Kingdom, published online July 9 in BMJ.
The new analysis is yet another study that adds to the controversy surrounding mammography's benefits and harms, which include overdiagnosis and overtreatment.
"The question is no longer whether overdiagnosis occurs, but how often it occurs," writes Gilbert Welch, MD, in an editorial accompanying the newly published analysis.
Overdiagnosis of cancer refers to cancers that grow so slowly that the patient dies of other causes before it produces symptoms or to cancer that is dormant or even regresses, explained Dr. Welch, who is a professor of medicine at Dartmouth Medical School in Hanover, New Hampshire.
Overdiagnosis is a "widely recognized problem" in prostate cancer screening, said Dr. Welch.
With regard to breast cancer, there is a growing body of evidence about overdiagnosis with which the new study is consistent, he added.
Namely, there are now 5 observational studies that indicate screening mammography is associated with increases in the incidence of breast cancer in women of screening age, but that there is "little or no subsequent decrease in the incidence of older women," notes Dr. Welch.
But is the rate of overdiagnosis really as high as 1 in 3 screen-detected cancers?
Dr. Welch says that that the "most compelling evidence to date" about overdiagnosis comes from an earlier randomized controlled trial of mammography versus observation (BMJ. 2006;332:689-692). In that study, overdiagnosis from screening occurred at a rate of 1 in 6, Dr. Welch notes.
Whatever the rate of overdiagnosis, both the study authors and the editorialist agree, overtreatment is likely to occur at the same rate.
"As it is not possible to distinguish between lethal and harmless cancers, all detected cancers are treated," write the study authors, Karsten Juhl Jørgensen, MD, and Peter C Gøtzsche, MD, from the Nordic Cochrane Center in Copenhagen, Denmark.
Close Call
The balance between the benefits and harms of mammography make it one of medicine's "close calls," adds Dr. Welch. It is a close call that has received a lot of public attention in the past year.
In the United Kingdom, there was public outcry over the lack of information about the harms of mammography in a public-health pamphlet about breast cancer screening. The protest led to a rewrite of the pamphlet, as reported by Medscape Oncology.
Furthermore, The New York Times and other media made front-page news out of a 2008 study from Norway that concluded that about 20% of screen-detected invasive breast cancers spontaneously regress. One of the Norwegian researchers told Medscape Oncology that such lesions are "pseudo-cancers."
In making decisions about whether or not to get screened, women are probably most interested in the "trade-off between the number of deaths from breast cancer avoided and the number of cancers overdiagnosed," suggested Dr. Welsh.
In an effort to provide physicians and their patients with a "balance sheet" of the harms and benefits of mammography, Dr. Welch included a tabular display along with his editorial. The credits and debits are for every 1000 women undergoing annual mammography for 10 years starting at the age of 50 years.
Credits :1 woman will avoid dying from breast cancer
Debits : 2–10 women will be overdiagnosed and treated needlessly
Credit: 10–15 women will be told they have breast cancer earlier than they would otherwise have been told, but this will not affect their prognosis
debit: 100–500 women will have at least 1 "false alarm" (about half these women will undergo biopsy)
New Study Details
To estimate the extent of overdiagnosis in organized screening programs, the Danish investigators compared trends in breast cancer incidence before and after the screening was initiated in the United Kingdom; Manitoba, Canada; New South Wales, Australia; Sweden; and parts of Norway.
The reason for this approach is based on the idea that, if screening was effective and did not produce overdiagnosis, then "the initial increase in cancers in the screened age groups would be fully compensated for by a similar decrease in the older age groups no longer offered screening," write the authors. Why is this so? Because the cancers in the older age groups would have been detected earlier on in life, as a result of screening, explain the authors.
The authors also note that such an approach must take into account changes in the background incidence of breast cancer and other factors.
One set of data offers an example of how the analysis was conducted. In Sweden, nationwide screening began in 1986, and in 1998, "almost all eligible women had been offered screening," the authors write. In 2000, the increase in invasive cancer after screening was implemented was 54% above expected rates for women aged 50 to 59 years and 21% for women aged 60 to 69 years. A drop in the incidence of breast cancer occurred among women aged 70 to 84 years, but the incidence "approached the expected rate," write the authors. In short, 88% of the increase among younger women was not compensated for by any drop in the older women, note the authors.
In summary, the total overdiagnosis of breast cancers, including ductal carcinoma in situ, from these public screening programs in different countries was 52%. The overdiagnosis of invasive breast cancer was 35%, report the authors.
BMJ. 2009;339:b1425 and b2587. Abstract, Abstract
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