Reducing the age of breast cancer screening to 40 years from 50 years could potentially reduce breast cancer mortality in women.

In the UK, breast cancer screening is offered every three years to women aged 50 to 70 years and it has long been debated whether screening women earlier would lead to an overdiagnosis of breast cancer.

The study led by Queen Mary University of London was published in The Lancet Oncology and randomised 160,000 women between 1990 and 1997 to receive either annual mammography, or the usual NHS breast screening at age 50.

In a new analysis of the UK Breast Screening Age Trial, which presents the 23-year follow-up results of the trial, it was found that screening women aged 40-49 led to a substantial and significant 25% reduction in breast cancer mortality in the first ten years.

The total years of life saved from breast cancer in the intervention group was estimated as 620, corresponding to 11.5 years saved per 1,000 women invited to earlier screening.

Benefits may be greater than seen in study due to new technology

The results also suggest at worst modest overdiagnosis in this age group, and that any overdiagnosed cancers would otherwise be diagnosed at NHS screening from 50 years of age. Therefore, screening in the age group of 40–49 years does not appear to add to overdiagnosed cases from screening at age 50 years and older.

Lead researcher Professor Stephen Duffy from Queen Mary University of London said: “This is a very long term follow-up of a study which confirms that screening in women under 50 can save lives. The benefit is seen mostly in the first ten years, but the reduction in mortality persists in the long term at about one life saved per thousand women screened.

“We now screen more thoroughly and with better equipment than in the 1990’s when most of the screening in this trial took place, so the benefits may be greater than we’ve seen in this study.”

The researchers say that more research is needed to clarify whether progress in early detection technology and treatment of breast cancer might modify the screening-related reduction in mortality in the 40-49 age group. They also did not consider the cost-effectiveness of lowering the screening age.

The study was funded by the National Institute for Health Research Health Technology Assessment programme, and included researchers from King’s College London, University of Nottingham, University of Dundee and Tel Aviv University.

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