The vicissitudes of breast screening
Michael Krasnitzer reports on a controversy without end
The benfit of breast cancer screening for women over aged 50 is beyond doubt. However, what does a systematic search yield for breast cancer in women aged between 40 and 49? This question, which remains controversial, was raised again at ECR 2012.
For Professor Andy Evans (Centre for Oncology & Molecular Medicine, University of Dundee, Scotland) the answer is positive: ‘Yes, there is good evidence that women in their 40s should have breast cancer screening.’ However, radiologist Matthew G Wallis MB ChB FRCR, at (Cambridge Breast Unit and the NIHR Cambridge Biomedical Research Centre, UK) believes this question cannot be answered conclusively: ‘It’s a question of the balance between the benefit and the damage.’
Screening advocate Prof. Evans bases his view on a series of studies that confirm the reduction of breast cancer-related mortality in women aged 40–49. However, he admits that these examinations have certain weaknesses. He is largely involved in the ‘Age Trail’, a current British study. The first study results, published in The Lancet, point towards a significant reduction in mortality but, as acknowledged in that specialist publication, are not statistically significant. Two Swedish studies, carried out in Malmö and Gothenburg, used examination procedures specifically geared towards this age group, which don’t correspond with the conventional breast cancer screening methods.
Although the critic Matthew Wallis shares the opinion that breast cancer screening lowers mortality, he points towards the problem of the many false positive screening results. ‘In around three in 1,000 women examined a carcinoma is detected – but in around 150 patients something is detected that necessitates further examinations,’ he emphasises. This leads to enormous costs and affects the quality of life for the affected patients. Moreover, Wallis also points towards the fact that tumours detected at an early stage are all lumped together, no matter whether they are fast growing aggressive tumours or slow growing and less aggressive ones.
The controversial age group of ‘women aged 40–49’ might just have been inappropriately chosen. ‘Maybe breast cancer screenings should start for patients aged from 45,’ suggests radiologist Dr Sophia Zackrisson (Skåne University Hospital in Malmö, Sweden). ‘We tend to look at ten-year groups, but there is no reason why we have to include 40-year-old women; it could be 45,’ Prof. Evans concedes. A move away from thinking in ten-year steps might be the solution to the controversy. Some countries have already drawn this conclusion. As announced only recently, starting from 2013, all women aged between 45 and 69 in Austria are to be regularly invited for a mammography by personal letter. Many radiologists are also convinced that better examination procedures are the answer to the problem. MRI facilitates a significantly better view into the breast than conventional mammography, stresses Dr Laura Martincich (Istituto per la Ricerca e la Cura del Cancro, Candiolo (Italy). ‘The use of MRI in breast cancer screening could significantly reduce the number of
false positive results.’
false positive results.’
Indeed, contrast-enhanced MRI is increasingly being used in clinical practice. ’In a high-risk population, the sensitivity of MRI is over 90%, whereas that of mammography plus ultrasound is 60-65% at best,’ explains head of radiology Prof. Francesco Sardanelli (IRCCS Policlinico San Donato, Milan, Italy). In terms of ‘high-risk population’ the professor is referring to those women who are at higher risk due to a familial history of mutations of certain genes (e.g. BRCA1). ‘Women in these risk groups should have annual examinations with MRI,’ he has stressed.
02.05.2012
More on the subject:
