A Cancer Research UK report produces the strongest evidence yet that organised breast screening programmes save lives.
The study, published in The Lancet1, shows breast cancer deaths dropped by almost half after an organised screening programme was introduced. The report also gives definitive evidence, for the first time, that screening younger women (40-49) significantly reduces mortality.
Scientists studied more than 200,000 Swedish women aged between 20 and 69. They compared the numbers of women who died from breast cancer in the pre-screening period with those who died after screening was introduced 2.
In the 40-69 age group breast cancer mortality was reduced by 44 per cent in those women who attended for screening. For women who were not screened during the second period the death rate reduction was just 16 per cent.
Among women aged between 40-49 the reduction in mortality was 48 per cent in those who were screened against 19 per cent among those who were not.
Stephen Duffy, Cancer Research UK’s Professor of Cancer Screening, says: “This produces very strong evidence that screening women for breast cancer, along with other improvements in breast cancer care, can almost halve the number of women who might otherwise die from the disease.
“While mammography is largely accepted by the scientific and medical community as a benefit to women, there are still some who express doubts as to its value. This study goes a long way towards silencing the dissenting voices.
“It also suggests there is a good case for offering younger women the chance to be screened if they have any additional risk of getting breast cancer such as a strong family history of the disease.”
“Sweden gives us a unique opportunity to study the results of breast cancer screening over 20 years, as the NHS screening programme was only gradually introduced between 1989 and 1993,” adds Prof Duffy.
Julietta Patnick, National Coordinator, NHS Breast Screening Programme, says: “This study will help reassure the 1.5 million women who are invited for screening in England, that the NHS Breast Screening Programme is an effective part of this country’s efforts in reducing the death toll from breast cancer.
“The breast screening programme has always been based on sound evidence and it has research programmes to examine the appropriateness of screening women under 50 and whether or not we need to alter the current screening interval.”
Cancer Research UK’s Sir Paul Nurse, says: “We have always believed in the value of the National Screening Programme. Now we have even more powerful evidence that screening saves lives. This is the kind of research that has a direct impact on the health and well-being of women and should reinforce the Government’s policy in urging women to take up their invitations to breast screening.”
- Lancet: Saturday 26 April, 2003
- Pre-screening: 1958-1977; Screening period 1978-1997. (In the UK the NHS screening programme was only gradually introduced between 1989 and 1993)
The study compares data for 20 years before and 20 years after the introduction of screening and is the first to show a complete 20-year follow-up. Adjustment has been made for other potential biasing factors such as increased incidence and self-selection for screening.
The study divided data into age groups invited for screening (40-69) and those not invited (20-39) and by whether or not women invited had actually received screening.
In the study women between 40 and 54 were screened every 18 months while older women were screened every two years.
In the UK, the interval between screens is three years, but recent trends in breast cancer mortality here suggest that the UK programme is also contributing to substantial reductions in breast cancer deaths.