EXPERTS have warned against the use of a specific type of scan on women with early breast cancer after fears it could lead to unnecessary surgery.
Magnetic resonance imaging (MRI) scans use strong magnetic fields and radio waves to produce a detailed image of the inside of the breast.
But researchers writing in the British Medical Journal said that the sophisticated equipment could lead to women having surgery on harmless lumps which do not change the course of their recovery.
Cancer charities said the technique was not frequently used in women with early breast cancer, but was useful in looking for the return of the disease in some patients.
One study of breast cancer patients being considered for non-surgical treatment found a 6 per cent increase in mastectomies - removals of the breast - in those who had a magnetic resonance mammography, according to the BMJ research.
Malcolm Kell, consultant surgeon and senior lecturer at University College Dublin, said the higher rates of surgery could be because such examinations are so sophisticated they pick up harmless recurrence or extension of tumours whose removal will not alter the outcome of the disease.
He said that while the scans were extremely useful in monitoring advanced breast cancer and assessing the response in the breast after chemotherapy, the use of this technology in early-stage breast cancer may do more harm than good.
"Magnetic resonance mammography identifies occult disease in the breast that may not be visible on other imaging modalities and this may lead to inappropriate treatment decisions," he said.
"There is no compelling evidence that this technique should be routinely used in newly diagnosed breast cancer."
But while supporters of the technique argue that using it routinely is likely to alert doctors to recurrence of the disease, the evidence does not back up their view, the researchers said.
Instead, Mr Kell suggested the best way to manage early-stage breast cancer and reduce the need for unnecessary and invasive surgery was through yearly monitoring and drug treatment, and radiotherapy where necessary.
Meanwhile Breast Cancer Care said it was unlikely that many women would be affected by the issues raised by Mr Kell as MRI was not routinely used on patients suffering the early stages of the disease.Clinical director Emma Pennery said: "MRI might detect recurrent disease but you don't necessarily know when you do a mastectomy whether leaving it alone would have harmed the patient or not."
Dr Lesley Walker, of Cancer Research UK, said: "We know that MRI scans are a very sensitive way of picking up breast cancer, but this can lead to more over-diagnoses and over-treatment.
"Doctors routinely use X-ray mammography to help decide how best to treat women with early-stage breast cancer, although MRI may be used to monitor women at high risk of inherited breast cancer.
"The mammograms women get through the NHS screening programme are X-rays, which are effective at picking up cancer at an early stage when the disease is often easier to treat."