Researchers from Germany have reported that MRI (magnetic resonance imaging) detects almost twice as many DCIS as mammography and is especially effective for detecting high-grade DCIS. The details of this study appeared in the August, 2007 issue of Lancet Oncology.[1] This data was also presented at the 2007 meeting of the American Society of Clinical Oncology (see first item of related news).

The goal of cancer screening is to detect cancer at an early stage, when treatment will be most successful. For the early detection of breast cancer, the American Cancer Society recommends an annual mammogram and clinical breast exam starting at the age of 40. In addition to mammography, women at high-risk of breast cancer are advised to receive annual screening with breast MRI. Although MRI has been reported to detect more breast cancers than mammography, it is also much more expensive and more likely to produce false-positive test results. Although it has been demonstrated that MRI is more sensitive than mammography in detecting invasive breast cancers, MRI's ability to detect DCIS has been doubted since this technique does not detect calcium.

The authors of this study compared 7,319 women who had both a mammogram and an MRI. They found that 193 women had surgically documented DCIS. Of these, 167 occurred in women who had a preoperative mammogram and an MRI. 

• MRI detected 92% of the DCIS cases and mammography detected 56% of the cases.
• 48% of high-grade DCIS were missed by mammography and all were detected by MRI.
• There were 2 cases missed by MRI that were detected by mammography and both were low-grade.

One explanation for these findings is that many DCIS cases do not contain calcium and would not be detected by mammography. The reason given for the effectiveness of MRI is that with contrast there is better visualization of neovascularization that occurs with DCIS.

Comments: This study suggests that MRI may be better than mammography at detecting DCIS—particularly high-grade DCIS. It should be noted, however, that this study was performed at a highly-specialized center with extensive experience with MRI. An accompanying editorial stated that “These findings can only lead to the conclusion that MRI outperforms mammography in tumour detection and diagnosis. MRI should thus no longer be regarded as an adjunct to mammography but as a distinct method to detect breast cancer in its earliest stage. A large multicentre breast screening trial with MRI in the general population is essential.”[2]

Reference: [1]  Kuhl CK, Schrading S, Wardelmann E, Braun M, Kuhn W, Schild HH. Magnetic resonance imaging versus mammography for diagnosing ductal carcinoma in situ. Proceedings of the American Society of Clinical Oncology. Chicago/ IL.  2007. Abstract # 1504.

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MRI Detects Cancer in Contralateral Breast Missed by Mammography in Women with Recently Diagnosed Breast Cancer (3/29/2007)

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Breast MRI May Influence Surgery Decisions (8/24/2006)

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MRI More Effective than Mammography for Women at High-Risk of Breast Cancer (8/6/2004)

Preoperative MRI Helps in Determining Extent of Surgery for Breast Cancer (7/22/2003)

German Researchers Suggest MRI to Replace Screening Mammography for Familial Breast Cancer (6/4/2003)