LISTEN: Tim Dower speaks to Van Henderson from The New Zealand Breast Cancer Foundation following Danish research which revealed about a third of breast cancer cases involved over-diagnosis. 

The researchers suggested screening isn't associated with a reduction in the number of advanced tumours.

Despite the research, women are being urged to keep getting their breasts screened.

But the Breast Cancer Foundation here says screening has close ties with reducing tumours.

Chief executive Van Henderson says while some women are treated for a lump that might not be harmful, it's better safe than sorry.

She says regular mammograms mean lower death rates.