But Dr Robin Wilson, secretary of the European Group for Breast Cancer Screening, will tell a news briefing (Tuesday 19 March) at the 3rd European Breast Cancer Conference in Barcelona, that even the Cochrane team were concerned about the validity of the Olsen and Gøtzsche review, with epidemiologists with knowledge of screening saying that the review itself was flawed.
"Whatever the issues are surrounding the claims and counterclaims about the validity of the trials and the review, the fact is that we have moved on a long way since the randomised trials that contributed to the review. Current evidence based on actual screening outcomes strongly supports its effectiveness," said Dr Wilson. He added that current evidence being presented today at the conference’s special day-long session on screening strongly supported its effectiveness.
He said that it was also vital to appreciate that the value of national screening programmes lay not just in their ability to detect breast cancer at an early stage, but also in the role they played in enhancing a country’s overall quality of care.
"When we talk about screening it is important to understand the difference between an organised and co-ordinated programme of population screening, which is concerned with reducing overall breast cancer mortality, and opportunistic screening, which may or may not benefit the individual women who accept," said Dr Wilson, who is Clinical Director of Breast Services in Nottingham, UK.
He said that a structured programme had a range of beneficial side-effects, which included the concentration of specialist multi-disciplinary expert teams who become highly skilled at diagnosing, treating and managing the disease.
However, he stressed that it was important to acknowledge that there could be drawbacks to screening. False positive results caused stress and anxiety for many women, particularly if a biopsy had also been required. And mammography was not perfect: breast cancers could be missed and this could give false reassurance to women who might therefore delay going to their doctor if they subsequently developed symptoms.
"Women must be properly informed about the benefits and disadvantages so they can decide for themselves whether they want to be screened. What is right for a governments, who naturally tend to concentrate on benefits to the population as a whole, might not necessarily be right for the individual."
Dr Wilson said that countries with full national screening programmes included the UK, Netherlands, Sweden, Finland and Luxembourg. Ireland, Belgium and Norway have introduced full national programmes although they are not yet totally available. Full population screening is available in some parts of Italy. Germany has started formally to introduce a national programme through three pilot programmes, and France, Portugal, Spain and Greece are still participating in EU-funded pilot programmes. Italy has many large regionally based programmes. Denmark and Switzerland have decided not to introduce screening programmes.
He concluded that while research was pressing on with improving screening through various new techniques such as digital imaging and computer aided detection (CAD) and these methods would be likely to contribute to effectiveness, they had not as yet, lived up to early expectations.
Spain pushes ahead with countrywide screening plans
The ongoing controversy has not deterred Spain from pushing ahead with its plans to have screening in place for the whole country. "In general, everybody agrees that breast cancer screening reduces cancer death by far more than 30% in the population included in the campaign," Dr Rafael Salvador told the news briefing. He said that the cancer detection rate was over 0.3% everywhere in Spain and had reached almost 0.5% in some areas.
However, the nature of its political structure meant that Spain has had to introduce screening gradually in different regions over the course of a decade.
Resources for screening are provided from a variety of sources, including the National Health Service, cancer associations, non-governmental organisations and many public and private institutions. Some communities have a long tradition of central government resources and self-management while others have only recently had resources and autonomy over health matters.
"But, nearly two-thirds of Spain is now covered by our breast cancer screening programme," said Dr Salvador, vice-president of the Spanish Society of Breast Imaging and president of the European Group for Breast Cancer Screening.
"We began with Navarro in 1990 and by the end of the 1990s all the regions had started their own programmes, although coverage varies from between 25 and 50% in Cataluña to 100% in the majority of regional programmes. In 1999 – the most recent year for which we have data – nearly 2.36 million women had access to screening and that was a 14% increase over the previous year. Our hope is that by the end of this year nearly everyone will have access to screening."
Dr Salvador, who is Associate Professor of Radiology at Vall d’Hebrón Hospital in Barcelona, said that although the regions all ran their own campaigns, quality control was assured by following the guidelines of the European Breast Cancer Network. In addition, screening programme directors met annually to reach consensus on issues such as research, evaluation and methodology. However, there were still differences between the programmes. All were agreed that screening should be at two-yearly intervals but, for example, the age of women screened varied, with some regions starting at age 45 and others at 50 and some finishing at 65 and some at 69.
Switzerland holds back ……not true says Swiss screening expert
The report from the Nordic Cochrane Center in Denmark that seven breast screening trials were flawed polarised discussion between the pro and anti screening camps, Dr Chris de Wolf, a consultant in cancer screening services from Geneva University, told the briefing.
"Polarisation brings in emotional elements and this is blurring scientific objectivity. It is important in the current discussion to distinguish between the scientific, political and public health aspects – including their objective and subjective values," he said.
He said that many people in Switzerland had been surprised to learn from a New York Times article that their country had decided not to proceed with nation-wide implementation of screening following the conclusions of the Danish report. But the information, issued by the Swiss Health Technology Council, had not been confirmed on their website or in the Swiss media.
"Such a statement is not surprising. Switzerland has probably the most complex health system in Europe – a mixture of a large private practice, socially insured health care, market forces and a shared responsibility between federal and cantonal level. There is no tradition on public health. Each canton may decide how it organises its public health services, so the statement in the New York Times may be valid for one canton but cannot be generalised to the other 25 cantons."
Dr de Wolf said that there were currently three programmes in operation (Vaud, Wallis and Geneva) and there were no indications that the Danish report had altered the decision to continue. There were even some other French speaking cantons preparing to start a screening service next year.
It was clear that the reports that Switzerland was holding back were biased, as the discussion on the evidence used in the Danish Cochrane Report had not even taken place at the time, said Dr de Wolf. A recent seminar in Sweden, attended by the report’s co-author Dr Gøtzsche, concluded that none of the so-called flaws had any relevance to the outcome of screening trials in Sweden, nor was there any convincing evidence that could give cause to reject the results of any of the trials. "The accusations of flaws proved to be groundless," he said.
Critics of screening completely ignored the experience of the countries that have introduced national programmes, he continued. "These countries are currently the only ones that show a clear reduction of breast cancer mortality compared with other countries in Europe. Maybe the results are not solely attributable to screening intervention, but the whole chain of prevention, cure and care has been made very effective and transparent and this may have nourished these results."
He concluded that one direct effect of the discussion about the controversial report was that the media were now trying to give more balanced reports. "We know mammograms are not perfect, but they are currently the best we have. Screening techniques have evolved - so has the information on the positive and the adverse effects. All this information must be made available to women. They are the ones who take the final decision whether or not to have a mammogram."