Screening women in their 40s for breast cancer would save a significant number of lives in the UK, research suggests.
Some women are deterred from being screened
A study by the charity Cancer Research UK has produced strong evidence that organised breast screening programmes save lives - and not just among women aged 50 and over.
In fact, breast cancer deaths dropped by almost half after an organised screening programme was introduced.
Researchers led by Dr Laszio Tabar, from Falun Central Hospital, compared the number of deaths from breast cancer in two Swedish counties 20 years before and
after screening was introduced in 1978.
The study involved 210,000 women aged 20 to 69 who had been diagnosed with breast cancer.
There is a good case for offering younger women the chance to be screened
Women aged between 40 and 54 were screened every 18 months while older women were screened every two years.
Women in the 44-69 years age group who received screening had a 44% reduced risk of dying from breast cancer compared with women in the same age group who were diagnosed before screening was introduced.
Part of this reduced risk is down to improvements in treatment, but the researchers believe around two-thirds can be put down to screening itself.
The death rates of those who did not take advantage of screening fell by only 16%.
Among women aged 40 to 49, death rates fell by 48% for those who were screened compared with 19% for those who were not.
Stephen Duffy, Cancer Research UK's Professor of Cancer Screening, said: "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."
Julietta Patnick, national coordinator of the NHS Breast Screening Programme, said the study would help to reassure women that breast screening was effective.
"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."
Breast screening was introduced gradually in the UK between 1978 and 1997.
At present, routine invitations for breast screening are sent to all women aged between 50 and 64 in the UK every three years. There are plans to extend this to women aged up to 70.
Delyth Morgan, chief executive of Breakthrough Breast Cancer described the research as a "breath of fresh air".
"It echoes our long-held beliefs that early detection and diagnosis are vital to improve a woman's chances of survival from breast cancer and the essential role the NHS screening programme plays in ensuring this.
"We now need to focus the screening debate on how to improve access to younger women at high risk or minority ethnic women."
Clara Mackay, director of policy and research at Breast Cancer Care said the research raised questions about whether or not the UK should lower the age at which women were offered routine access to screening.
"We would strongly recommend a review of the breast screening programme to consider whether the age limit should be lowered.
"We need to be confident that screening services are available to everyone whom would benefit - regardless of age."
The research is published in The Lancet medical journal.