Video published on 19 Nov 2016 by Show More Spine.
Paul Glasziou’s Interview by Alan Cassels at Preventing Overdiagnosis Conference 2016 in Barcelona, Spain.
Watch more videos about overdiagnosis on YouTube.
A clear insight about over diagnosis in less than 3 mns
Mammograms tied to overdiagnosis of breast cancer
The current study offers fresh evidence linking routine screening to over-diagnosis of non-aggressive tumors because it compares outcomes over a single time period in two regions of Denmark – one that offered biennial mammography for women aged 50 to 69 and one that didn’t.
Effective breast cancer screening should detect early-stage cancer and prevent advanced disease.
To assess the association between screening and the size of detected tumors and to estimate overdiagnosis (detection of tumors that would not become clinically relevant).
Breast Cancer Screening in Denmark: A Cohort Study of Tumor Size and Overdiagnosis, Annals of Internal Medicine, DOI: 10.7326/M16-0270, 10 JANUARY 2017.
Philips Mammography Truck, Brazil via philips_newscenter.
Denmark from 1980 to 2010.
Women aged 35 to 84 years.
Screening programs offering biennial mammography for women aged 50 to 69 years beginning in different regions at different times.
Trends in the incidence of advanced (>20 mm) and nonadvanced (≤20 mm) breast cancer tumors in screened and nonscreened women were measured. Two approaches were used to estimate the amount of overdiagnosis: comparing the incidence of advance and nonadvanced tumors among women aged 50 to 84 years in screening and nonscreening areas; and comparing the incidence for nonadvanced tumors among women aged 35 to 49, 50 to 69, and 70 to 84 years in screening and nonscreening areas.
Screening was not associated with lower incidence of advanced tumors. The incidence of nonadvanced tumors increased in the screening versus prescreening periods (incidence rate ratio, 1.49 [95% CI, 1.43 to 1.54]). The first estimation approach found that 271 invasive breast cancer tumors and 179 ductal carcinoma in situ (DCIS) lesions were overdiagnosed in 2010 (overdiagnosis rate of 24.4% [including DCIS] and 14.7% [excluding DCIS]). The second approach, which accounted for regional differences in women younger than the screening age, found that 711 invasive tumors and 180 cases of DCIS were overdiagnosed in 2010 (overdiagnosis rate of 48.3% [including DCIS] and 38.6% [excluding DCIS]).
Regional differences complicate interpretation.
Breast cancer screening was not associated with a reduction in the incidence of advanced cancer. It is likely that 1 in every 3 invasive tumors and cases of DCIS diagnosed in women offered screening represent overdiagnosis (incidence increase of 48.3%).
Breast-Cancer and Mammography : Consider the Pros and Cons
How Tiny Are Benefits From Many Tests And Pills? Researchers Paint A Picture
Mammograms are said to cut the risk of dying from breast cancer by as much as 20 percent ; some researchers want people to question that kind of thinking.
NEJM Screening Mammograms, Analysis by Dr. H. Gilbert Welch
Dr. H. Gilbert Welch gives us a brief explanation of the findings of the New England Journal of Medicine article “Breast Cancer Tumor Size, Overdiagnosis, and Mammography Screening Effectiveness“, October 13, 2016.
The goal of screening mammography is to detect small malignant tumors before they grow large enough to cause symptoms. Effective screening should therefore lead to the detection of a greater number of small tumors, followed by fewer large tumors over time.
We used data from the Surveillance, Epidemiology, and End Results (SEER) program, 1975 through 2012, to calculate the tumor-size distribution and size-specific incidence of breast cancer among women 40 years of age or older. We then calculated the size-specific cancer case fatality rate for two time periods: a baseline period before the implementation of widespread screening mammography (1975 through 1979) and a period encompassing the most recent years for which 10 years of follow-up data were available (2000 through 2002).
After the advent of screening mammography, the proportion of detected breast tumors that were small (invasive tumors measuring
Although the rate of detection of large tumors fell after the introduction of screening mammography, the more favorable size distribution was primarily the result of the additional detection of small tumors. Women were more likely to have breast cancer that was overdiagnosed than to have earlier detection of a tumor that was destined to become large. The reduction in breast cancer mortality after the implementation of screening mammography was predominantly the result of improved systemic therapy.
Which country will be first to stop mammography screening?
The Canadian Task Force on Preventive Health Care should be congratulated for its new recommendations on screening for breast cancer in women at average risk aged 40–74 years. These guidelines are more balanced and more in accordance with the evidence than any previous recommendations.
The recommendations against routine clinical breast examinations, breast self-examinations and magnetic resonance imaging to screen for breast cancer in this age and risk group are all straightforward.
The recommendations on mammography screening are even more conservative than the change in policy suggested by the US Preventive Services Task Force in 2009, which created an uproar in the United States from people interested in maintaining the status quo. The new Canadian guidelines are appropriately cautious, advising against routinely screening women aged 40–49 years. The task force recommends screening women aged 50–69 years every two to three years, although it admits that this is a weak recommendation based on moderate-quality evidence, and screening women aged 70–74 years on the same schedule based on low-quality evidence. The task force also suggests that women who do not place a high value on a small reduction in breast cancer mortality, and who are concerned with false-positive results on mammography and overdiagnosis, may decline screening.
These guidelines are an important step in the right direction, away from the prevailing attitude that a woman who does not undergo screening is irresponsible. Recent research even suggests that it may be most wise to avoid screening altogether, at any age, as outlined below.
The Canadian Task Force on Preventive Health Care decided not to include observational studies in its systematic review unless they were needed to elucidate the harms of screening or the values and preferences of patients. However, important observational studies have been published in recent years, without which a systematic review would be incomplete. These observational studies have been discussed elsewhere and have also been included in an update (currently submitted for publication) of our 2009 Cochrane review of mammography screening.
Time to stop mammography screening?; National Institutes of Health PMC3225414 183(17): 1957–1958, Nov 22 2011.
Programming a latest-gen mammography station, nicoyogui.
If screening does not reduce the occurrence of advanced cancers, it does not work. A systematic review of studies from seven countries showed that, on average, the rate of malignant tumours larger than 20 millimetres was not affected by screening. Because the size of a tumour is linearly correlated to the risk of metastasis, this result is evidence against an effect of screening.
Denmark has a unique control group within its population — only 20% of its population was screened during a 17-year period. The annual decrease in breast cancer mortality in the relevant age group (55–74 years) and period was 1% in the areas with screening and 2% in the non-screened areas.Among women who were too young to benefit from screening, the decreases were larger (5% for screened areas, 6% for unscreened areas). Similar results have been reported from the United Kingdom, Sweden and Norway.
A study involving women from 30 European countries showed that the mean decrease in breast cancer mortality between 1989 and 2005 among women less than 50 years of age was 37%; the corresponding decrease was 21% among women aged 50–69 years. The declines began before the start of organized screening programs in many countries and are more likely explained by the introduction of tamoxifen. The introduction of tamoxifen could explain the larger decline seen among young women who often have estrogen-sensitive tumours.
Another study compared three pairs of similar neighbouring countries that had introduced screening 10–15 years apart. The pairs were Northern Ireland and the Republic of Ireland, the Netherlands and Belgium, and Sweden and Norway. There was no relation between start of screening and the reduction in breast cancer mortality.The fall in breast cancer mortality was about the same in all countries. Furthermore, the decline was also about the same as that seen in the United States, where screening started as early as in Sweden.
Screening seems to be ineffective in today’s world for two reasons. First, adjuvant therapy, such as tamoxifen and chemotherapy, is highly effective (even when the cancer has metastasized) but was not often used at the time of the old trials. Second, public awareness of breast cancer has increased, and women tend to see a doctor much earlier today when they have noticed something unusual in their breast. In Denmark, the average size of a tumour decreased by nine millimetres from 1979 to 1989, a reduction that occurred before screening started. In addition, this decrease was larger than the average difference in tumour size seen between screened and control groups in trials (5 mm), despite the tendency for small, overdiagnosed tumours to spuriously exaggerate the difference.
It has often been claimed that mammography screening reduces breast cancer mortality by 30%. However, thorough systematic reviews have estimated only a 15% reduction, and data on tumour size from the trials are compatible with only a 12% effect.This effect is similar to the results seen in the most reliable studies, which showed a 10% effect after 13 years.
Any possible effect of screening on breast cancer mortality must be marginal and could be counteracted by the life-shortening effect that radio-therapy and chemotherapy have when used in healthy women in whom breast cancer has been overdiagnosed (i.e., a diagnosis of breast cancer that would not have been made in the woman’s remaining life had she not undergone screening). The main effect of screening is to produce patients with breast cancer from among healthy women who would have remained free of breast disease for the rest of their lives had they not undergone screening. Compelling data from the US, Norway and Sweden show that most overdiagnosed tumours would have regressed spontaneously without treatment. In addition, screening substantially increases the number of mastectomies performed, despite routine claims to the contrary by advocates of screening.
The best method we have to reduce the risk of breast cancer is to stop the screening program. This could reduce the risk by one-third in the screened age group, as the level of overdiagnosis in countries with organized screening programs is about 50%.
If screening had been a drug, it would have been withdrawn from the market. Thus, which country will be first to stop mammography screening?
Peter Gøtzsche, MD, 2011.
New way to define disease is needed to reduce overdiagnosis
A new process is needed for defining diseases that takes account of the potential risks of overdiagnosis and overtreatment as well as the benefits of appropriate diagnosis and care, researchers, policymakers, and consumer groups agreed at an international congress this week.
“The problem at the moment is that we don’t have an internationally agreed process,”
said Paul Glasziou, professor of evidence based practice at Bond University, Robina, Queensland.
“Disease definitions are developed on a very ad hoc basis, often by guideline panels making recommendations about tests and treatments who, along the way, incidentally change the definition of a disease,”
he told the Preventing Overdiagnosis conference, co-sponsored by The BMJ and held on 20-22 September in Barcelona.
“We have a clear, internationally agreed process on what evidence is needed to recommend a particular treatment. But there has been a neglect of the fundamental issue that comes before that, which is the definition of disease.”
An Opportunity for Improvement
Over the past 30 years, awareness and screening have led to an emphasis on early diagnosis of cancer.
Although the goals of these efforts were to reduce the rate of late-stage disease and decrease cancer mortality, secular trends and clinical trials suggest that these goals have not been met; national data demonstrate significant increases in early-stage disease, without a proportional decline in later-stage disease.
Unbelievable scam of cancer industry blown wide open: $100 billion a year spent on toxic chemotherapy for many FAKE diagnoses… National Cancer Institute’s shocking admission affects millions of patients, natural news, October 08, 2015.
What has emerged has been an appreciation of the complexity of the pathologic condition called cancer. The word “cancer” often invokes the specter of an inexorably lethal process; however, cancers are heterogeneous and can follow multiple paths, not all of which progress to metastases and death, and include indolent disease that causes no harm during the patient’s lifetime.
Overdiagnosis and Overtreatment in Cancer, An Opportunity for Improvement, JAMA, August 28, 2013.
Better biology alone can explain better outcomes. Although this complexity complicates the goal of early diagnosis, its recognition provides an opportunity to adapt cancer screening with a focus on identifying and treating those conditions most likely associated with morbidity and mortality.
Incertain dépistage organisé
Porté par des enjeux humains et de santé publique, le documentaire suit le parcours de quatre femmes confrontées, un jour, à la peur du cancer du sein. Leurs histoires sont le point de départ d’une enquête scientifique qui bouscule nos certitudes..
Tous les ans au mois d’octobre, la campagne pour le dépistage bat son plein. Mais depuis quelques années, la controverse monte:
Too many treatments can be harmful,
Too much medicine can cause angst, confusion and harm
Video published on 27 Oct 2015
Advances in medicine have propelled health care to new heights and a vast array of diagnostic tests and drug therapies is now available. But are we getting too much of a good thing?
Do More Screening Tests Lead to Better Health?
Choosing Wisely Canada is a campaign to help physicians and patients engage in conversations about unnecessary tests, treatments and procedures.