A comprehensive review of breast cancer screening of millions of women in Europe concludes that in terms of lives saved, the benefits outweigh the harms of over-diagnosis.

The findings of the review, led by researchers at Queen Mary, University of London, are published in a special 13 September supplement to the The Journal of Medical Screening.

They show that for every 1,000 women aged 50 to 68 or 69 tested every two years, breast screening saves between seven and nine lives, and leads to four cases of over-diagnosis.

The findings also show that for every 1,000 women tested, 170 are recalled at least once to undergo further non-invasive tests before confirming there is no cancer (negative result).

Also, for every 1,000 tested, 30 women are called back at least once to undergo invasive tests such as biopsy (where a small sample of breast tissue is cut away and sent for analysis), before confirming a negative result. Such cases are termed “false positives” and can cause undue worry and stress while patients wait for the results.

The review includes results from EUROSCREEN, the European Screening Network working group, which has members from nine European countries where the screening is followed up and outcomes assessed. The EUROSCREEN countries are: Denmark, Germany, Italy, France, Norway, Spain, Sweden, The Netherlands, and the United Kingdom.

The group reviewed European published studies that had estimated breast cancer deaths prevented and rates of major harms from screening, particularly cases of “over-diagnosis”, where screening results lead to diagnoses of cancers that would never have shown symptoms during patients’ lifetimes, and would not have been diagnosed by other means.

The review also includes results from EUNICE, the European Network for Indicators on Cancer working group. This group reviewed 26 breast screening programmes used by 12 million women in 18 countries between 2001 and 2007. The data covers the performance, take up rate, and organization of the programmes.

The countries in EUNICE are: Belgium, Czech Republic, Denmark, Estonia, Finland, Germany, Hungary, Italy, Luxembourg, Norway, Poland, Portugal, Republic of Ireland, Spain, Sweden, Switzerland, The Netherlands, and the United Kingdom.

Stephen Duffy, EUROSCREEN coordinator and co-author of the paper, told the press theirs was the only comprehensive review of breast screening services in Europe.

“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,” said Duffy, who is Professor of Cancer Screening at the Wolfson Institute of Preventive Medicine at Barts and The London School of Medicine & Dentistry at Queen Mary, University of London.

“In particular, it is good news that lives saved by screening outweigh over-diagnosed cases by a factor of two to one,” he added.

Eugenio Paci, Director of the Cancer Prevention and Research Institute in Florence, Italy, is also a EUROSCREEN coordinator and co-author of the paper. He said it was important to offer women the chance to be fully aware of the benefits versus the harms for when they decide whether to attend breast cancer screening.

“There has been quite a lot of discussion recently over the worth of breast cancer screening and for this reason it is timely that the international group of experts has assessed the impact of population-based screening in Europe and has found that it is contributing to the reduction in deaths from the disease,” he explained.

Paci said not only should women offered breast screening in Europe be told about these findings, but every effort should be made to raise their awareness, and to make relevant information accessible and easy to understand.

Breast cancer is the most common cancer in women worldwide. In 2008, the year for which the most recent figures are available, around 1.38 million women found out they had the disease.

In the UK, the lifetime risk of being diagnosed with breast cancer is one in eight.

In Europe, around 100,000-140,000 cancers are detected by screening each year among women aged 50 to 69.

Another study published recently in Cancer Epidemiology, Biomarkers and Prevention that followed about 4,000 women in Australia also concludes that breast cancer screening saves lives.

University of Melbourne Research Fellow Carolyn Nickson and colleagues said their findings affirmed the importance and effectiveness of mammography.

Written by Catharine Paddock PhD