An MRI exam in every six months could be far more effective in detecting breast cancer in younger women with a high-risk genetic profile than an annual mammogram, according to a study.

The results suggest that for this population, intensive efforts to "downstage" aggressive breast cancer by finding small early lesions in women with high-risk mutations are crucial to improving outcomes.

"This study demonstrates, for the first time, that aggressive breast cancers can be caught early, without excessive recalls or biopsies," said Olufunmilayo Olopade, from the University of Chicago in the US.

Between 2004 and December 2016, the researchers recruited 305 women into a clinical trial.

Volunteers had to have a lifetime breast cancer risk greater than 20 per cent. More than half of the women enrolled (53 per cent) had mutations in breast cancer related genes, such as BRCA1, BRCA2 or CDH1.

After evaluation by a physician and a genetic counsellor, the participants were scheduled to undergo a clinical breast examination and a dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) scan every six months, and a digital mammogram every 12 months.

"Mammograms remain important for most women. But for women at high risk who are getting a DCE-MRI every six months, annual mammograms could probably be eliminated," Olopade said.