As part of its campaign against "too much medicine" the British Medical Journal has published reviews that question the value of screening for breast cancer in women and aneurysm in men – asking whether the harm of "over-diagnosis" outweighs the benefit of detecting and treating real cases of disease, reports Medical News Today.
In the case of breast cancer, the analysis of the history of screening for the disease, written by a public health expert, calls for "urgent agreement" in the debate and controversy that exists between scientists.
For abdominal aortic aneurysm, the review about screening men who do not have symptoms suggests that the ratio of harm to benefit of carrying out these programs has worsened over the years. This, they say, is thanks to a reduction in risk factors such as smoking, which has reduced the chance that screening will succeed in finding actual cases.
And a third paper looks at the results of surveys that gauged the level of over-diagnosis people would accept from screening programs aiming to detect different cancers – finding a wide range of attitudes to the harm or benefit of screening.
Agreement on best estimates of breast cancer over-diagnosis is urgently needed to inform women, because very different estimates are blocking effective communication about this.
In 2012, prompted by increasing debate about over-diagnosis, an independent UK panel estimated that about 19% of breast cancers diagnosed among women invited to mammogram screening were in fact over-diagnosed (they would have been harmless). But other estimates have been higher (up to 50%) or lower (less than 5%).
More than any other debate about over-diagnosis, the discussion of breast cancer has spilt from the pages of the specialist medical press into the public domain, argues Alexandra Barratt, professor of public health at the University of Sydney. She says, achieving consensus seems unlikely in the short term but resolution should be a high priority so that women can be given objective, balanced and uncontested information.
Breast cancer is the most common cancer in women worldwide. Early trials reported that screening reduced the risk of dying from breast cancer by around 30% in women over 50 and led to publicly funded mammography screening programs in many countries in the 1980s and 90s.
Although this has led to large increases in detection of early breast cancer, rates of advanced cancer have declined only slightly or remained relatively stable, suggesting that mammography screening is detecting low risk or non-progressing breast cancer that would never have become life threatening.
In the NHS screening programme, 99% of women with screen detected breast cancer undergo surgery and around 70% also have radiotherapy and hormone therapy. If around 20% of these breast cancers are over-diagnosed, then about 20% of these women are undergoing treatments to "cure" a disease which they would never had had without screening, explains Barratt.
She also argues we should think twice before introducing new breast imaging technologies, such as tomosynthesis (3D mammography) or extending screening to older and younger women, until incremental net benefit to women has been demonstrated in high quality studies.
Changing screening policy "should be based on demonstrated ability to achieve equivalent benefit to harm ratios and not on the assumption that increased detection will achieve a net benefit." Lastly, she calls for more balanced information for women and says participation targets should not be set and should not be regarded as a marker of health service quality.
Aneurysm screening for men over 65 should be revisited as it is unknown whether the benefits outweigh the harms, researchers argue.
The decision to introduce abdominal aortic aneurysm (AAA) screening was based on four randomised controlled trials from the 1980s and 1990s. Over the last 15 years Sweden, the UK and the US have introduced AAA screening programmes. But researchers based at the Universities of Gothenburg and Copenhagen argue that that screening almost doubles AAA prevalence, yet most AAAs are small and at low risk of rupture. They estimate that 176 of every 10,000 men invited to screening are over-diagnosed.
"These men are unnecessarily turned into patients and may experience appreciable anxiety throughout their remaining lives. Moreover, 37 of these men unnecessarily have preventive surgery and 1.6 of them die as a consequence," they explain.
They also point to several studies showing a drop in AAA prevalence over recent decades, probably because the prevalence of smoking has fallen. "When the incidence of the condition screened for decreases, the potential benefits also decrease," write the authors. "Furthermore, the benefit:harm ratio is likely to be worse in current screening programmes than in the trials on which they were based."
And they warn that plans to lower the diagnostic threshold for AAA "will double AAA prevalence and substantially increase the rate of over-diagnosis." "Screening programmes have changed the meaning of an AAA diagnosis from a life threatening condition to a risk factor," argue the authors. "AAA screening programmes should be revisited because of reduced benefits in modern populations and because data suggest considerable harm," they conclude.
People have highly variable views on how much over-detection is acceptable in cancer screening, a UK survey has found. The authors say invitations for screening "should include clear information on the likelihood and consequences of over-detection to allow people to make an informed choice."
Over-detection describes cancerous lesions that are picked up and treated but would never have caused symptoms or become fatal in a person's lifetime. This is typically seen if the cancers are so slow growing that they would not have been detected if screening had not taken place. Yet little is known about how much over-detection people would find acceptable for cancer screening, and whether acceptability depends on the level of benefit and perceived harms.
So a team of researchers at the University of Oxford's Nuffield Department of Primary Care Health Sciences performed an online survey of 1,000 people aged 18 or older living in the UK, representative for age and sex according to the 2011 UK census – just under a third (29% of respondents had heard of over-detection before.
The survey included questions on three different types of cancer screening: breast cancer (for women), prostate cancer (for men), and bowel cancer (for both men and women). For each type separately, the researchers presented the absolute number of cases per year in the UK and a description of the treatment, including adverse effects.
They then presented two different screening scenarios – one indicating a 10% reduction in cancer-specific deaths and the second indicating a 50% reduction. Immediately after each scenario, they asked respondents about the maximum number of people over-detected and over-treated that they would accept for the given benefit. The respondents were allowed to indicate a number between zero (the minimum) and 1,000 (entire population as maximum).
Describing the results, the paper’s lead author, Dr Ann van den Bruel, director of the NIHR Oxford Diagnostic Evidence Cooperative and senior clinical research fellow in Oxford University's Nuffield Department of Primary Care Health Sciences, says: "We found that people have highly variable views about how much over-detection they would accept in cancer screening, with up to seven percent indicating they would accept no over-detection at all and up to 14% who would accept over-detection in the entire population. Across the different cancer types, people would accept a median of 113 to 150 people to be over-detected to avoid one person dying of cancer as a result of screening."
"People accepted more over-detection when they perceived a higher benefit from cancer screening, so from a 10% mortality reduction to 50% mortality reduction, median acceptability increased significantly, with a maximum of 313 cases per 1,000 people screened for breast cancer," she adds.
The study showed that acceptability of over-detection for bowel cancer screening was significantly lower than for breast cancer screening in women and prostate cancer screening in men. "This might have been caused by the inclusion of a one in 20 mortality risk of surgery in the description of bowel cancer treatment," van den Bruel explains.
Generally, people aged 50 or over accepted less over-detection, whereas people with a higher education accepted more. People who suffer from a chronic condition were more likely to accept over-detection in at least 80% of the screened population.
Van den Bruel says: "How much over-detection people are willing to accept depends on the benefit that screening produces, and the cancer-specific harms of over-detection. Additionally, personal preference is influenced by age, education level and whether people have other illnesses. To allow people to make an informed choice that is aligned with their personal values, we as a research community should get better at measuring not only the benefits but also the harms associated with cancer screening, and properly convey that information when people are invited."
A new systematic review of dozens of studies on patients' expectations quantifies exactly how unrealistic they are when it comes to their medical care, says a Vox report. It turns out they almost always see the glass as half full, despite the evidence that suggests they actually shouldn't.
Looking at 36 studies on a range of medical interventions – from cancer screening tests to medications and surgeries – a pair of Australian researchers discovered that, overwhelmingly, patients overestimated the benefits and underestimated the harms.
In the 32 studies that looked at how patients perceived the benefits of a medical intervention, most (65%) overestimated them. On the other hand, the studies that looked at patients' perceptions of harms found a majority (67%) underestimated them.
This means when patients walk into hospitals and clinics and sign up for tests, treatments, and procedures, they are unrealistically optimistic. And they too often forget about the possible downsides of the things they are exposing themselves to.
The researchers found this was as true for patients' notions about the accuracy and helpfulness of mammograms and Pap smears as it was for their ideas about the medications – like hormone therapy – they take, and even the usefulness of ultrasounds to detect foetal problems in pregnancy.
"Participants rarely had accurate expectations of benefits and harms," the study authors wrote, "and for many interventions, regardless of whether a treatment, test, or screen, they had a tendency to overestimate its benefits and underestimate its harms."
This "optimism bias" is driven by several factors, the study authors contend: the marketing practices of industry, doctors' failure to communicate with patients about risk-benefit ratios, and the hopefulness and trust we place in health care and the medical profession.
Unrealistic expectations are having knock-on effects, the authors continue, driving patients' desire for more care instead of less, even when it confers no help and it may in fact hurt them. They suggest that this is "undoubtedly contributing to the growing problem of over-diagnosis and over-treatment."
[link url="http://www.medicalnewstoday.com/articles/290229.php"]Full Medical News Today report[/link]
[link url="http://www.bmj.com/company/wp-content/uploads/2015/03/agreement-on-breast-cancer-overdiagnosis.pdf"]British Medical Journal material[/link]
[link url="http://www.bmj.com/content/350/bmj.h867"]BMJ article[/link]
[link url="http://www.bmj.com/company/wp-content/uploads/2015/03/aneurysm-screening.pdf"]British Medical Journal material[/link]
[link url="http://www.bmj.com/content/350/bmj.h825"]British Medical Journal article[/link]
[link url="http://www.bmj.com/company/wp-content/uploads/2015/03/Cancer-screening-survey.pdf"]British Medical Journal material[/link]
[link url="http://www.bmj.com/content/350/bmj.h980"]British Medical Journal article[/link]
[link url="http://www.vox.com/2015/3/7/8161407/risk-benefit-medicine"]Full Vox report[/link]
[link url="http://archinte.jamanetwork.com/article.aspx?articleid=2038981"]JAMA Internal Medicine abstract[/link]