Frequent mammograms may do more harm than good, according to researchers from the Nordic Cochrane Centre in Denmark.

The research shows that women undergoing breast screening are being "misinformed" and are not told about the harms of over-diagnosis. They said that the screening information should be more balanced.

Following the research, a review is underway in the UK of breast screening. The British national cancer director, Professor Mike Richards has begun an independent study of the research evidence about mammograms.

The review can bring to light new evidence and existing advice should be reviewed in the light of the new evidence. The British Medical Journal, Professor Susan Bewley, consultant obstetrician at King's College, London wrote in an open letter that mammograms may not be as beneficial as many believe.

She found the NHS leaflets "exaggerated benefits and did not spell out the risks. The oft-repeated statement that '1,400 lives a year are saved' has not been subjected to proper scrutiny. Even cancer charities use lower estimates." In a response Prof Richards said that "screening programmes should be based on the best available evidence".