A Dutch study to look at the effectiveness of breast cancer screening, shows that although treatments have also improved, population-based mammography initiatives still save lives.
Mrs Rianne de Gelder, a PhD student and researcher at the Erasmus University Medical Center (Rotterdam, The Netherlands), presented the research at the eighth European Breast Cancer Conference (EBCC-8) in Vienna, adding to the debate surrounding screenings, that suggests they might do more harm than good.
There is a growing argument against national screening programs, with detractors saying that treatment for the disease is so effective nowadays, that the chances of surviving it are as good as if the tumor had been detected slightly earlier via a national screening program. There is a growing belief that these national programs lead to unnecessary investigations, over-treatment and worry, not to mention that the scan is relatively physically aggressive to the breasts themselves and also involves blasting them with x-rays on a regular basis.
Dutch researchers however, say they identified that screening every two years reduced deaths by an additional 15.7%. They say that treatment given in addition to primary therapy, such as surgery, has also reduced deaths by 13.9% in 2008, when compared to no treatment.
Gelder, explained to the conference that using a computer modeling technique called microsimulation, her team had showed that adjuvant treatment reduced deaths from breast cancer from 67.4 per 100,000 women years to 57.9.
With the addition of two-yearly screening between the ages of 50-75 (the current screening age in The Netherlands), Gelder showed the deaths fell to 48.8 per 100,000 women years, thus adjuvant therapy and screening reduced deaths by a total of 27.4%.
Gelder and colleagues take the offensive against the detractors to national programs and go on to claim that screenings should be extended to women aged between 40-49, to create a further further 5.1% reduction in deaths from breast cancer. This would theoretically give national screen a total reduction in breast cancer deaths of 31.1% lead over no program at all.
Mrs de Gelder continued that :
“The effectiveness of breast cancer screening has been heavily debated in the last couple of years. One of the arguments that critics have is that, since breast cancer patients can be treated so effectively with adjuvant therapy, the relative effects of screening become smaller and smaller. Our study shows that, even in the presence of adjuvant therapy, mammography screening (between age 50 and 75) is highly effective in reducing breast cancer deaths … and, in fact, is slightly more effective than adjuvant treatment. Screening women of these ages should definitely continue …
In addition, if screening could be started before the age of 50, the breast cancer mortality could be further reduced, even when breast cancer patients are effectively treated by adjuvant therapy. It has the potential to further decrease breast cancer mortality by up to 5.1% when 10 additional annual screening examinations starting from age 40 are performed. Policy makers should investigate further the ideal age for starting screening, taking into account not only the effects, but also the risks and costs of extending the lower age limits.”
Mrs de Gelder concluded:
“It is important to note that our study demonstrated that the observed reduction in breast cancer mortality in The Netherlands could not fully be explained by mammography screening and adjuvant therapy only.
Other, unknown causes are likely to have contributed to fewer deaths as well. These causes may, for instance, include further developments in breast cancer diagnostics and treatment. It may also be possible that the effects of screening and adjuvant treatment are even larger than currently assumed in the model.”
Professor David Cameron, from the University of Edinburgh (Edinburgh, UK), and chair of EBCC-8 said:
“This paper will make an important contribution to the ongoing debate about the level of benefit of a population-based mammographic screening program. Many aspects of breast cancer management have improved since the original randomised trials of breast cancer screening, and so it is important to dissect out the relative contributions of treatment, screening and other changes in the management.”
Written by Rupert Shepherd