Benefits of breast cancer screening outweigh harms
Washington: A major review of breast cancer screening services in Europe, jointly led by researchers at Queen Mary, University of London, has found that the benefits of screening in terms of lives saved outweigh the harms caused by over-diagnosis.
The results showed that for every 1,000 women screened every two years from the age of 50 to the age of about 68-69, between seven and nine lives would be saved, and four cases would be over-diagnosed.
The European Screening Network (EUROSCREEN) working group, with members from nine European countries where outcome of screening programmes have been assessed, reviewed the estimates of benefit in published European studies in terms of breast cancer deaths prevented, and the major harms, in particular, the rates of what are called “over-diagnosed” cancers.
These are breast cancers diagnosed as a result of screening, which would never have given rise to any symptoms during a woman’s lifetime and would not have been diagnosed had she not been screened.
A second working group – European Network for Indicators on Cancer (EUNICE) – reviewed the organisation, participation rates and main performance parameters of 26 screening programmes in 18 countries, involving 12 million women, between 2001 and 2007.
The reports from both working groups have contributed to the latest study.
“This is the only comprehensive review of the results of breast screening services in Europe,” said Stephen Duffy, Professor of Cancer Screening at the Wolfson Institute of Preventive Medicine at Barts and The London School of Medicine and Dentistry, part of Queen Mary, University of London (UK), who is one of the coordinators of the EUROSCREEN working group and co-author of the supplement.
“It reports results from screening millions of women, and confirms that the screening services are delivering the benefits expected from the research studies conducted years ago. In particular, it is good news that lives saved by screening outweigh over-diagnosed cases by a factor of two to one,” he noted.
The researchers also found that for every 1,000 women screened, 170 women would have at least one recall followed by a non-invasive assessment before absence of cancer could be confirmed (a negative result), and 30 women would have at least one recall followed by invasive procedures, such as a biopsy, before confirming a negative result. Screening results that lead to recalls in these circumstances are called” false positives” and can cause women stress and anxiety until the negative result is confirmed.
The results have been published in a special supplement of The Journal of Medical Screening.