Some women diagnosed with early breast cancer in one breast are later found to have cancer in the other breast. Even careful clinical examination and mammography can fail to identify early lesions, so the question arises as to whether more extensive investigations - such as magnetic resonance imaging (MRI) - should not be carried out routinely at the time of the initial diagnosis.
Lehman et al (NEJM 2007;356:1295-303) report on nearly 1 000 women across the US who had early cancer in one breast with negative mammography and clinical examination in the other who then had MRI of the “cancer-free” breast. Within one year of the initial diagnosis they found 3% of the women had or developed cancer in the contralateral breast.
The sensitivity and specificity were not as high as ideally required in a screening test but, with a negative predictive value of 99%, women may well find it acceptable. The cancers found in the contralateral breast were all early and had not spread so MRI evaluation should be considered if malignancy is found in one breast, even if routine investigations are apparently negative.
