Using magnetic resonance imaging (MRI) to diagnose breast cancer in its intraductal stage could help prevent the development of invasive cancer, conclude authors of an Article in this weeks edition of The Lancet. And an accompanying Comment says that the findings show that MRI should now be used as a distinct method in its own right to detect breast cancer in its earliest stage.
Professor Christiane Kuhl, Department of Radiology, University of Bonn, Germany and colleagues studied 7319 women over a five-year period who had been referred to an academic breast centre. The women received MRI in addition to conventional mammography for diagnostic assessment and screening, with the aim of discovering the sensitivity of each method for diagnosing ductal carcinoma in situ (DCIS). Mammograms and MRI scans were then assessed independently by different radiologists, and the relative sensitivity of each method of detection was assessed by comparing the biological profiles of mammography-detected DCIS with those of MRI-detected DCIS.
The researchers found that of 167 women who had a diagnosis of DCIS, 153 (92%) were diagnosed by MRI compared with 93 (56%) diagnosed by mammography. Whereas the sensitivity of MRI for diagnosing DCIS increased with nuclear grade, that of mammography decreased. Of 89 women diagnosed with high grade DCIS, 87 (98%) were diagnosed by MRI, but only 46 (52%) by mammography. Accordingly, almost half (48%) were missed by mammography but diagnosed by MRI alone. They also found that age, menopausal status, personal or family history of breast cancer, and breast density of women with MRI-only diagnosed disease did not differ significantly from those of women with mammography-diagnosed DCIS. The higher sensitivity of MRI was not associated with an unduly high number of false positive diagnoses - the positive predictive value of both methods was comparable, with 55% for mammography, and 59% for MRI.