Mostrando las entradas con la etiqueta Breast cancer screening. Mostrar todas las entradas
Mostrando las entradas con la etiqueta Breast cancer screening. Mostrar todas las entradas

12 junio, 2013

Más criticas al cribado de cáncer de mama

Shown is a breast being compressed to get the ...Visión crítica sobre la detección de cáncer de mama mediante mamografía (Revisión Cochrane)

 Desde el excelente blog de Rincón Docente, Luis Lozano, nos informa de esta nueva iniciativa de colaboración Cochrane.
  | Dejar un comentario
Cochrane Collaboration
Cochrane Collaboration (Photo credit: Wikipedia)
Peter C. Gøtzsche es un conocido investigador danés líder del Centro Nórdico Cochrane de Copenhague, Dinamarca. Ha escrito numerosas evaluaciones dentro de la colaboración Cochrane.
Además de sus trabajos criticos sobre la investigación con placebos y los posibles sesgos de los metaanálisis es especialmente conocido por su voz crítica sobre el cribado del cancer de mama, sobre los que ya publicó un artículo de 2000 en Lancet (Is screening for breast cancer with mammography justifiable?).
Acaba de publicarse una revisión Cochrane sobre el screening de cancer de mama mediante mamografía escrita por él en colaboración con Karsten Juhl Jørgensen. Creo que se trata de una revisión que invita a la reflexión. Me he permitido traducir las conclusiones:
Shown is a breast being compressed to get the optimum mammographic image. (Photo credit: Wikipedia)
Implicaciones para la Práctica Clínica
Creemos que ha llegado el momento de reevaluar si la mamografía de cribado universal debería ser recomendada para cualquier grupo de edad. La disminución de las tasas de mortalidad por cáncer de mama se deben principalmente a la mejora de los tratamientos y la concienciación sobre el cáncer de mama, por lo que no estamos seguros de los beneficios del cribado en la actualidad. El sobrediagnóstico tiene costes humanos y aumenta el número de mastectomías y muertes. La probabilidad de que una mujer se beneficie del asistir a las pruebas  de cribado es pequeña, y en el mejor de los casos – si nos basamos en los resultados de ensayos aleatorios – diez veces más pequeño que el riesgo de que pueda experimentar daños graves en términos de sobrediagnóstico. Las mujeres, los médicos y los responsables políticos deben valorar cuidadosamente ventajas y desventajas cuando se decide si es adecuado o no asistir o apoyar programas de cribado.
Los defensores del cribado y de diversas  organizaciones en general han hecho hincapié en los beneficios y omitido información sobre los principales daños en sus materiales de información (Dixon-Woods, 2001; Gøtzsche 2012; Jørgensen 2004; Folleto NHS 2001; Folleto NHS 2010; EE.UU. Task Force 2002) y en cartas de invitación (Jørgensen 2006; Gøtzsche 2009). Por tanto la mayoría de las mujeres tienden a exagerar considerablemente los beneficios y no ser conscientes de los principales efectos nocivos del cribaje (Barratt 1997; Barratt 1999; Domenighetti 2003, Schwartz 2000).
Para intentar ayudar a asegurar que la mujer reciba una información adecuada para decidir si acudir o no a un programa de cribado, hemos redactado un folleto para pacientes basado en la evidencia disponible (Gøtzsche 2009). El folleto ha sido probado cuidadosamente entre los médicos generales y pacientes. Está disponible en el sitio web de BMJ en Inglés (Gøtzsche 2009) y en varios idiomas en el sitio web del Centro Nórdico Cochrane en http://www.cochrane.dk (acceso al folleto en español)
Se ha sugerido que estos recursos podrían redirigirse a intervenciones con beneficios comprobados en el cáncer de mama (Baum 2000) o utilizarse para otros fines (NBCC 2002). En comparación, el beneficio es al menos 200 veces mayor en las mujeres con cáncer de mama con ganglios positivos que son tratados con tamoxifeno ya que la extensión media de vida es de seis meses a los 10 años (EBCTCG 1998).
Implicaciones para la investigación
La mortalidad por cáncer de mama resulta poco fiable como medida de resultado de las pruebas de cribado (y por tanto también de los estudios de cohortes sobre eficacia de los programas nacionales) y exagera su beneficio. Debido a los problemas metodológicos de los ensayos de detección y los análisis reaalizados, sería útil que investigadores independientes realizaran un metanálisis basado en datos de pacientes individuales, donde no se permitiera la exclusión de las mujeres al azar. También sería útil obtener datos sobre todas las muertes por cáncer  de todos los ensayos ya que la clasificación errónea de la causa de la muerte a menudo se refiere a muertes por otros cánceres. Por último, es necesario investigar en métodos que permitan diferenciar los cánceres susceptibles de producir mayor mortalidad de los muchos tumores benignos identificados que no necesitarían tratamiento.

Related articles

No hay comentarios.: Labels: , , , , , , , ,

30 mayo, 2013

Frequency of Mammography: Age, Breast Density, and Hormone Therapy


Practice Update

JAMA Intern Med 2013 May 01;173(8)807-816, K Kerlikowske, W Zhu, RA Hubbard, B Geller, K Dittus, D Braithwaite, KJ Wernli, DL Miglioretti, ES O'Meara



TAKE-HOME MESSAGE

This large, prospective cohort study found that biennial screening mammography for most women aged 40 to 49 and 50 to 74 years, even among those with high breast density or receiving combination hormone therapy (risk factors for breast cancer), results in similar risks of presenting with advanced-stage disease as with annual screening mammography. Most women who undergo annual mammography are at high risk of false-positive results without benefit from the more frequent screening. However, a small proportion of women aged 40 to 49 with extremely dense breasts are more likely to present with advanced-stage disease if they undergo biennial vs annual screening; this benefit is counterbalanced by a higher risk of cumulative false-positive mammography results with annual screening.
Screen all women aged 50 to 74 biennially (regardless of breast density or hormone therapy use). When counseling women aged 40-49 about breast cancer screening, those with extremely high density breasts should be informed that annual mammography may minimize their risk of presenting with advanced-stage disease but the cumulative risk of false-positive results is high.



SUMMARY
PracticeUpdate Editorial Team
Updated US guidelines recommending that women aged 50 to 74 years undergo mammography biennially, instead of every 1 to 2 years as previously recommended, do not take into account women with additional breast cancer risk factors, such as increased breast density and postmenopausal use of hormonal therapy (HT). More frequent screening may be advantageous in these women, but few studies have reported outcomes when risk factors are combined with frequency of screening mammography.
This study evaluated women aged 40 to 74 years undergoing screening mammography in a community setting to determine whether the benefits (detection of early-stage disease) and harms (false-positive result or biopsy recommendation) differed by screening frequency according to age, breast density, and postmenopausal HT use. Breast Cancer Surveillance Consortium mammography registry data from 1994 through 2008 were used to identify women with and without breast cancer who had undergone annual, biennial, or triennial screening mammography. Analyses for benefit included 11,474 women with at least two screening examinations before diagnosis with breast cancer. Most of these women were aged ≥ 50 years, and > 50% had heterogeneously dense or extremely dense breasts. Analyses for harm included 922,624 women with no previous breast cancer and no cancer within 1 year of screening. Of these women aged 40 to 49 years, 55.1% had extremely dense breasts.
The risk of presenting with advanced-stage breast cancer was similar for most women aged 40 to 49 years and 50 to 74 years screened biennially compared with those screened annually, including those women with high breast density or who were receiving combination HT. Only women aged 40 to 49 years with extremely dense breasts were at increased risk of presenting with advanced-stage rather than early-stage disease when screened biennially vs annually (adjusted odds ratio [AOR] = 1.89; 95% CI, 1.06-3.39) and of presenting with a tumor size > 20 mm (AOR = 2.39; 95% CI, 1.37-4.18). Women aged 50 to 74 years with heterogeneously dense or extremely dense breasts who were receiving combination HT had an apparent, but nonstatistically significant, increased risk of advanced-stage disease (AOR = 1.56; 95% CI, 0.88-2.80) and tumor size > 20 mm (AOR = 1.59; 95% CI, 0.97-2.61) with biennial vs annual screening.
Annual screening was associated with a high probability of a false-positive mammography result in most women, with probability decreasing as the screening interval increased. Women aged 40 to 49 years were most likely to have at least one false-positive recall after 10 years of subsequent annual mammography, with cumulative probabilities of 68.9% and 65.5% in women with heterogeneously dense or extremely dense breasts, respectively. Likewise, women aged 50 to 74 years receiving combination HT and with heterogeneously dense or extremely dense breasts had similarly high cumulative probabilities of a false-positive result with annual screening (68.1% and 65.8%, respectively). Lowest cumulative probabilities were seen in women with fatty breasts across both age groups and regardless of combination HT use (30.3%–36.3%). Cumulative probabilities of at least one false-positive biopsy recommendation after 10 years were much lower than those of a false-positive recall, although of a similar pattern.
This study found that, with the exception of women aged 40 to 49 years with extremely dense breasts, biennial screening mammography was associated with a similar risk of presenting with advanced-stage disease compared with annual screening mammography, but overall the probability of a false-positive screening result was higher.



JAMA internal medicine
Outcomes of Screening Mammography by Frequency, Breast Density, and Postmenopausal Hormone Therapy
JAMA Intern Med 2013 May 01;173(8)807-816, K Kerlikowske, W Zhu, RA Hubbard, B Geller, K Dittus, D Braithwaite, KJ Wernli, DL Miglioretti, ES O'Meara
Abstract  

Related articles

Enhanced by Zemanta
No hay comentarios.: Labels: , , , , , , ,

18 abril, 2013

Screening cancer with mammography

English: Breast cancer incidence by age in wom...
English: Breast cancer incidence by age in women in the United Kingdom 2006-2008. Reference: Excel chart for Figure 1.1: Breast Cancer (C50), Average Number of New Cases per Year and Age-Specific Incidence Rates, UK, 2006-2008 at Breast cancer - UK incidence statistics at Cancer Research UK. Section updated 18/07/11. (Photo credit: Wikipedia)
Age-standardised death rates from Breast cance...
Age-standardised death rates from Breast cancer by country (per 100,000 inhabitants). (Photo credit: Wikipedia)
Screening with mammography uses X-ray to try to find breast cancer before a lump can be felt. The goal is to treat cancer early, when a cure is more likely. The review includes seven trials that involved 600,000 women who were randomly assigned to receive screening mammograms or not. The review found that screening for breast cancer likely reduces breast cancer mortality, but the magnitude of the effect is uncertain. Screening will also result in some women getting a cancer diagnosis even though their cancer would not have led to death or sickness. Currently, it is not possible to tell which women these are, and they are therefore likely to have breasts or lumps removed and to receive radiotherapy unnecessarily. The review estimated that screening leads to a reduction in breast cancer mortality of 15% and to 30% overdiagnosis and overtreatment. This means that for every 2000 women invited for screening throughout 10 years, one will have her life prolonged. In addition, 10 healthy women, who would not have been diagnosed if there had not been screening, will be diagnosed as breast cancer patients and will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress for many months because of false positive findings.
It is thus not clear whether screening does more good than harm. Women invited to screening should be fully informed of both the benefits and harms. To help ensure that the requirements for informed consent for women contemplating whether or not to attend a screening program can be met, we have written an evidence-based leaflet for lay people that is available in several languages on www.cochrane.dk.

Related articles

No hay comentarios.: Labels: , , , , , ,

28 noviembre, 2011

More abut stop mammography

Source: Vancouver Sun


 
Radiologist Dr. Paula Gordon, a leading B.C. breast-cancer expert and medical director of BC Women's Breast Health Program, predicts an increase in cases and deaths if women and doctors pay too much heed to “alarming” recommendations from a Canadian task force. Gordon is pictured at a press conference in January 2011.
 
More Images »
 

Radiologist Dr. Paula Gordon, a leading B.C. breast-cancer expert and medical director of BC Women's Breast Health Program, predicts an increase in cases and deaths if women and doctors pay too much heed to “alarming” recommendations from a Canadian task force. Gordon is pictured at a press conference in January 2011.

Photograph by: Nick Procaylo, PNG files

VANCOUVER — A leading B.C. breast-cancer expert predicts an increase in cases and deaths if women and doctors pay too much heed to “alarming” recommendations from a Canadian task force.
Radiologist Dr. Paula Gordon doesn’t deny that screening can occasionally lead to false positives, overdiagnosis and overtreatment. But she said certain studies were ignored — including a B.C. one — that show a 25-per-cent reduction in mortality among women screened by mammograms.
The task force also put too much stock on research that was poorly designed or was done decades ago, she contends.
“False positives can indeed cause harm because they can be traumatizing, and I agree that women should consider the potential harm of screening. But it is absurd that the task force is recommending no self-examination by women [without risk or symptoms] and no clinical examination by family doctors,” said Gordon, who was reacting to the task force report as chairwoman of an early detection working group of the Canadian Breast Cancer Foundation (BC/Yukon). She is also medical director of the breast health program at B.C. Women’s Hospital.
“This puts us back to the 1960s because the task force relied on old trials using equipment that is now obsolete. So it’s advising women in their 40s to make decisions based on scientific evidence that is older than they are,” said Gordon, referring to the advice against regular screening for low-risk women aged 40 to 49.
Gordon said mammograms do turn up abnormalities that are not cancerous, but false positives are inevitable and occur in all screening tests, including pap smears for cervical cancer. However, she cited surveys that show even with the risks of false positives, women would still rather have tests or even biopsies done, rather than delay diagnosis and treatment.
As to the task force’s recommendation that women at average risk of breast cancer have no need to routinely examine themselves or seek the same from doctors, “women are effectively being told to wait till they see a lump in their breast in the mirror before they seek treatment.
“ By that time, even with excellent care, mortality rates will return to what they were in the 1970s.”
Task force members, including Simon Fraser University researcher Michel Joffres, said not all breast tumours require treatment because some small ones may spontaneously regress. But Gordon disputed that.
“Nobody has evidence of self-healing and regression,” she said. “When we see cancer, it is not possible to predict how long it will take to grow. Just because we need to get better at knowing these things doesn’t mean it’s okay to stop looking for cancer.”
Joffres said about 12 per cent of women who go for screening are told they have an abnormality, and of those, seven per cent will be told, after further testing, they have cancer. One study showed that five of every 1,000 women aged 39 and older screened through mammography may be overdiagnosed and have unnecessary surgery to remove breasts or portions of them “and that is not an insignificant proportion,” he said.
Joffres and Gordon did agree on one thing: more confusion for women and primary care doctors. Joffres said the task force guidelines are meant to provoke more informed discussion between women and their doctors.
“These are weak recommendations; we’re not saying don’t do it,” he said.
B.C. was the first province in Canada to establish a breast cancer screening program in 1988. Women aged 40 to 79 are offered an X-ray at least every two years. Twenty per cent of cancers occur in women in their 40s, 25 per cent in females in their 50s, 27 per cent in their 60s and 28 per cent of breast cancers occurs in women over 70, Gordon said.
Carol Thorbes, an SFU communications officer who had routine mammograms and was considered an average risk when she was diagnosed with breast cancer at 49, said she’s concerned doctors will be less vigilant as a result of the proposed guidelines.
Her sister in Ontario died of breast cancer at 46 and Thorbes says there are pronounced differences between the provinces, with B.C. doctors far more supportive of routine screening, even in low-risk patients.
Sun Health Issues Reporter
 
 
 


Read more:http://www.vancouversun.com/health/Mammogram+recommendations+alarming+could+lead+more+deaths+expert/5746627/story.html#ixzz1f0zpR6tm
No hay comentarios.: Labels: ,

Time to stop mammography screening

Mammakarzinom, ID T1b. Mammography, breast can...Image via Wikipedia

Time to Stop Mammography Screening-CMAJ 2011
Related articles
No hay comentarios.: Labels: , , , , , , ,

27 octubre, 2011

British breast cancer screening now under independent review

Normal (left) versus cancerous (right) mammogr...Image via Wikipedia

Source: Health News Review

By Gary Schwitzer on October 26, 2011 8:21 AM  No Comments  No TrackBacks
Questions about how best to communicate to the public about the tradeoffs of potential benefits versus potential harms of mammography do not end at America's shores.
An independent investigation into breast cancer screening has been set up by the government's cancer chief to try to settle the growing controversy around its usefulness and potential harms.
Prof Sir Mike Richards's move is an attempt to put to rest the criticisms of a number of scientists, who say the NHS (British National Health Service) screening programme wrongly identifies cancers that might never harm women, leading to unnecessary and potentially damaging treatment with surgery, drugs and radiation therapy.
They also contest the official NHS position, which is that although there is some over-treatment as a result of screening, mammograms save lives.
The BMJ today published a letter from Susan Bewley, professor of complex obstetrics, Division of Women's Health, King's College London, to the man BMJ calls "England's cancer tsar," Mike Richards. Excerpt of her letter: 
"I declined screening when it was offered, as the NHS breast screening programme was not telling the whole truth. As a non-expert in the subject, I found myself examining the evidence for breast screening with increasing doubts. I compared the NHS and Nordic Cochrane Centre leaflets and found that the NHS leaflets exaggerated benefits and did not spell out the risks. Journals showed a reputable and growing body of international opinion acknowledging that breast cancer screening was not as good as used to be thought. The distress of overdiagnosis and decision making when finding lesions that might (or might not) be cancer that might (or might not) require mutilating surgery is increasingly being exposed. The oft repeated statement that "1400 lives a year are saved" has not been subjected to proper scrutiny. Even cancer charities use lower estimates. I expressed my misgivings to you "behind the scenes" as a work colleague. You replied in a personal email "that the large majority of experts in this country disagrees with the methodology used in the Cochrane Centre reviews of breast screening."
It is extraordinary to be told that methodology is contentious so many years into the national programme."
"I take the current controversy very seriously. I will do my best to achieve consensus on the evidence, though I realise this may not ultimately be possible. Should the independent review conclude that the balance of harms outweighs the benefits of breast screening, I will have no hesitation in referring the findings to the UK National Screening Committee and then ministers. You also have my assurance that I am fully committed to the public being given information in a format that they find acceptable and understandable and that enables them to make truly informed choices."

Related articles
No hay comentarios.: Labels: , , , , , , ,

24 octubre, 2011

Most women with screen-detected breast cancer have not had their life saved by screening

Age-standardised death rates from Breast cance...Image via Wikipedia
By Gary Schwitzer on October 24, 2011 4:42 PM  No Comments  No TrackBacks
That's the conclusion of an article published today in the Archives of Internal Medicine. I'm on the run today, but here's the abstract: 

Background Perhaps the most persuasive messages promoting screening mammography come from women who argue that the test "saved my life." Because other possibilities exist, we sought to determine how often lives were actually saved by mammography screening.
Methods We created a simple method to estimate the probability that a woman with screen-detected breast cancer has had her life saved because of screening. We used DevCan, the National Cancer Institute's software for analyzing Surveillance Epidemiology and End Results (SEER) data, to estimate the 10-year risk of diagnosis and the 20-year risk of death--a time horizon long enough to capture the downstream benefits of screening. Using a range of estimates on the ability of screening mammography to reduce breast cancer mortality (relative risk reduction [RRR], 5%-25%), we estimated the risk of dying from breast cancer in the presence and absence of mammography in women of various ages (ages 40, 50, 60, and 70 years).
Results We found that for a 50-year-old woman, the estimated risk of having a screen-detected breast cancer in the next 10 years is 1910 per 100 000. Her observed 20-year risk of breast cancer death is 990 per 100 000. Assuming that mammography has already reduced this risk by 20%, the risk of death in the absence of screening would be 1240 per 100 000, which suggests that the mortality benefit accrued to 250 per 100 000. Thus, the probability that a woman with screen-detected breast cancer avoids a breast cancer death because of mammography is 13% (250/1910). This number falls to 3% if screening mammography reduces breast cancer mortality by 5%. Similar analyses of women of different ages all yield probability estimates below 25%.
Conclusions Most women with screen-detected breast cancer have not had their life saved by screening. They are instead either diagnosed early (with no effect on their mortality) or overdiagnosed.







Related articles
No hay comentarios.: Labels: , , , , , , ,

17 septiembre, 2011

Breast Cancer Screening


By Graham McMahon

The latest article in our Clinical Practice series reviews current recommendations for breast-cancer screening and thesupporting evidence, including the controversy regarding mammographic screening of women in their 40s.
Worldwide, breast cancer is now the most common cancer diagnosed in women and is the leading cause of deaths from cancer among women, with approximately 1.3 million new cases and 458,000 deaths reported in 2008.OK

Clinical Pearls

• How have the screening recommendations from the U.S. Preventive Services Task Force (USPSTF) changed in recent years?
In contrast to its 2002 guidelines, the more recent recommendations of the USPSTF, published in November 2009, support a reduction in the use of screening mammography. The two most controversial changes were the reclassification of screening for women between the ages of 40 and 49 years from a B recommendation (based on moderately strong evidence) to a C recommendation (“the decision . . . should be an individual one and take into account patient context, including the patient’s values regarding specific benefits and harms”), and the recommendation that the frequency of screening be reduced from every 1 to 2 years to every 2 years.
• What is the consensus recommendation regarding mammographic screening for women between the ages of 50 and 69?
Screening mammography for women 50 to 69 years of age is universally recommended. All but one of the trials that included women in their 60s showed a significant reduction in mortality in the screened group, although this was not true for the subgroup of women in their 50s. Still, a meta-analysis revealed significant reductions in the number of deaths in both these age groups — 14% for women in their 50s and 32% for those in their 60s.

Morning Report Questions

Q: For a 42-year-old woman with no risk factors, what are the benefits and risks of screening mammography?
A: Her chance of having invasive breast cancer over the next 8 years is about 1 in 80, and her chance of dying from it is about 1 in 400. Biennial mammographic screening will detect two out of three cancers in women her age and will reduce her risk of death from breast cancer by 15%. However, there is about a 40% chance that she will be called back for further imaging tests and a 3% chance that she will undergo biopsy, with a benign finding.
Q: What are the benefits of digital mammography?
A: The contrast between breast tumors and surrounding normal parenchyma is greater with digital mammography than with film mammography, particularly when the breast tissue is dense. In one study in which almost 50,000 asymptomatic women 40 years of age or older underwent both digital and film mammography, the two techniques were equivalent overall in sensitivity (70% and 66%, respectively) and specificity (92% for both). However, in women under the age of 50 years, digital mammography was significantly more sensitive than film (78% vs. 51%).

Related articles
Enhanced by Zemanta
No hay comentarios.: Labels: , , , , , , ,
Suscribirse a: Entradas (Atom)