Jane Flanders was not aware of the risks involved in being screened for breast cancer when she received her invitation from the National Health Service four years ago.

After being diagnosed with cancer and undergoing extensive surgery, the mother of two now wishes she had not attended. She believes she was the victim of over-diagnosis.

The 56-year-old maths teacher from Basingstoke, Hampshire, was diagnosed with ductal carcinoma in situ, a dormant cancer which was not spreading and may never have caused problems.

Doctors advised her to have radical treatment — including a mastectomy — in case it might spread.

“Screening has caused me considerable and lasting harm. It has certainly not saved or prolonged my life,” she said.

“The reality of this diagnosis has been two wide excisions, one partial mutilation (sorry, mastectomy), one reconstruction, five weeks’ radiotherapy, chronic infection, four bouts of cellulitis (a bacterial infection), several general anaesthetics and more than a year off work.”

Flanders believes it is “outrageous” that the NHS has withheld information on the risks. The government has been forced to rewrite its advice to include warnings about potential harm caused by the screening process.

The NHS information that Flanders received, along with her invitation to screening, failed to mention anything about ductal carcinoma in situ and the possible consequences of over-diagnosis.

Flanders said: “It is infantilising women. It is patting them on the head and saying ‘There, there, it will be all right’. It is entirely dishonest.”

Research from the Nordic Cochrane Centre in Denmark, published in the British Medical Journal (BMJ) this year, reported that if 2,000 women are screened regularly for 10 years, one life will be saved but 10 healthy women will be treated unnecessarily. This treatment includes removal of part or all of their breast, radiotherapy or chemotherapy.

The new advice will include how many women need to be screened to save one life and the estimated levels of overdiagnosis.

The government does not accept the figures published in the BMJ paper and a debate is under way over which statistics to give to women. NHS data shows that 14,110 cancers were diagnosed as a result of screening in 2007-8, 3,000 of which were not invasive.

There has been pressure to lower the age at which screening is offered after the diagnosis of cancer in Kylie Minogue, the Australian singer, when she was in her late thirties. At present women are offered screening once they reach 50.

This week British scientists and doctors will fuel the debate by publishing a guide that warns of the disadvantages as well as benefits of all types of screening. Making Sense of Screening by the charity Sense About Science, will warn that it can have negative effects as well as beneficial ones.

Professor Peter Furness, president of the Royal College of Pathologists which helped to produce the document, said: “It is about the public understanding [of screening] and realising that screening does harm as well as good. Screening programmes result in further tests that can do harm.

“With prostate cancer, particularly in older men, there is the possibility of treating something that is so slowgrowing it doesn’t really need to be treated. It can get very complicated as to whether screening is a good idea or not.

“In some of the literature they put out on these screening programmes, in order to encourage people to take it up, sometimes the uncertainties get glossed over.”

The NHS Breast Screening Programme estimates that 1,400 lives are saved every year as a result of 1.7m women in England being screened.

Julietta Patnick, director of the programme, said: “The NHS Breast Screening Programme is committed to helping women make informed choices about their breast screening invitation. Part of this is helping them assess the risks and the benefits of screening for breast cancer.

“The review of the leaflet has been under way for some months and the examination of the literature has been completed. We are on track to produce the leaflet ... this year.”

Explore Health

• Expert Advice

• Health Features

• Mental Health

• Alternative Medicine

• Child Health

• Health Club