1 in 10 breast cancer treatments 'unnecessary'

March 2, 2006

Conservative estimate, imho. Probably much higher - DCIS is relatively

common from what I've read.

Boseley, health editor

Friday March 3, 2006

The Guardian

One in 10 women diagnosed with breast cancer undergoes unnecessary

treatment, according to research that suggests some cancers that would

probably not have caused any harm during a woman's lifetime are being picked

up by rigorous screening.

While screening reduces the death rate, over-diagnosis is inevitable in a

programme that is designed to catch breast cancers early. But the scale of

over-diagnosis has not been known and estimates have varied from 1% to 54%.

In the British Medical Journal today, scientists in Sweden where the

original trials were carried out that paved the way for the NHS screening

programme, publish a study that gives a definitive over-diagnosis

calculation of 10%.

A team from Malmö University hospital followed participants from the trials

which took place between 1976 and 1986.

As well as the control group who had not been offered breast screening, they

used cancer registries to track down the numbers of women who had been

diagnosed with breast cancer - with or without screening - up to December

2001.

They found that 10% more women had been diagnosed and treated for breast

cancer in the screened group than in the non-screened group. This suggests

that 10% of the cancers would not have caused a problem if they had not been

detected and the women had not had treatment. In a separate paper in the

BMJ, researchers in Denmark call for more balanced information about

screening to be included in literature given to women when they are invited

to attend, which in the UK is after the age of 50.

The researchers examined information sent to women from 30 English-speaking

and Scandinavian countries, including the UK, and found it leaned heavily in

favour of screening.

None of the invitations explained there was a risk of over-diagnosis.

Two-thirds (68%) of invitations gave an appointment date, but the authors

believe that information material should convey the message that a decision

not to attend is not irresponsible.

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