Using MRI to diagnose breast cancer in women with dense breasts

While there has been considerable progress in the areas of awareness, testing and treatment, it is estimated that more than 70 Canadians will be diagnosed with breast cancer each day and 5,100 women will die from breast cancer in 2020.[i] This represents 13% of all cancer deaths in women in Canada.

While mammograms are the primary screening technique to diagnose breast cancer, MRI has shown to have advantages as a screening tool.[ii] In a recent randomized controlled trial investigating screening with mammography versus MRI in women with a familial risk, MRI was shown to find more instances of breast cancer. In addition, tumour stages of the cancers detected were earlier in the MRI group.[iii]

Further screening studies in women with dense breasts have shown that supplemental imaging with MRI, in addition to mammography, has benefits in terms of detecting more breast cancers.[iv] Breast density is a measure of the ratio of fibrous tissue versus fat within a breast and can vary among women. Mammograms of dense breasts are harder to read than mammograms of fatty breasts. Tumors appear white on a mammogram and therefore can be difficult to see if there is dense tissue.[v]

Dense breast tissue acts like clouds making the sun harder to see in the sky.