Breast cancer screening ‘leads to over-diagnosis’

An official study found that as many as 4,000 women in Britain receive therapy for non-life threatening forms of the disease every year because of over-diagnosis. However it also revealed that about 1,300 lives are saved by mammography.

The NHS Breast Cancer Screening Programme was launched in the UK in 1988 and invites all women aged between 50 and 70 to screening every three years. However has been an ongoing debate about the benefits and harms of screening for the past 10 years, prompting the government and charity Cancer Research UK to launch a review of the controversial programme last year.

An independent panel concluded that screening reduces breast cancer mortality but that some overdiagnosis occurs. It found that for every life saved, three women were overdiagnosed.

As the review shows, some cancers will be diagnosed and treated that would never have caused any harm. Dr Harpal Kumar, Cancer Research UK

The panel, led by University College London’s Professor Sir Michael Marmot, was tasked with analysing data from screening trials from a number of countries over recent decades.

Its report, published in The Lancet, said that for every 10,000 UK women aged 50 years invited to screening for the next 20 years, 43 deaths from breast cancer would be prevented and 129 cases of breast cancer, invasive and non-invasive, would be overdiagnosed. “That is one breast cancer death prevented for about every three overdiagnosed cases identified and treated,” the panel said.

However the authors of the report urged caution on the exact figures, saying: “Since the estimates provided are from studies with many limitations and whose relevance to present-day screening programmes can be questioned, they have substantial uncertainty and should be regarded only as an approximate guide.”

Professor Sir Mike Richards, National Cancer Director, said: “I welcome the fact that the review clearly recommends that breast screening should continue.

“But the key thing is that we communicate this new information to women so they can make an informed choice for themselves. NHS Cancer Screening programmes have already asked independent academics to develop new materials to give the facts in a clear, unbiased way. I hope to see them in use in the next few months.

Dr Harpal Kumar, chief executive of Cancer Research UK, said: “The independent review shows screening saves lives. Screening remains one of the best ways to spot the very early signs of breast cancer, at a stage when treatment is most likely to be successful.

“Yet, as the review shows, some cancers will be diagnosed and treated that would never have caused any harm. Clearly, everyone wants to minimise this.”