In an editorial also published by the BMJ, Mr Gilbert Welch, a professor at the Dartmouth Institute for Health Policy and Clinical Research in Vermont, said the findings raised the key question about the trade-off between deaths avoided and harm inflicted by screening programmes.

One study has suggested that one death is avoided for every two women who are 'overdiagnosed,' while another puts the ratio far higher, at one death avoided for every 10 cases of unnecessary treatment.

Welch called on the medical profession to draw up a simple statistical table to help women weigh the risks and the benefits from breast-cancer treatment.

'Mammography undoubtedly helps some women but hurts others,' said Mr Welch.

'No right answer exists, instead it is a personal choice.' -- AFP