New Study Suggests Better Detection of DCIS Possible with MRI
August 13, 2007 - A study published in the August 11, 2007 issue of The Lancet reports that the use of magnetic resonance imaging (MRI) could improve the ability to diagnose ductal carcinoma in situ (DCIS), especially DCIS that is classified as high grade. High-grade DCIS is more likely to become invasive breast cancer.
Details of the Study
Over five years, 7,319 women at the breast center at the University of Bonn Hospital and Medical School in Germany (an academic national breast center) were screened with MRI in addition to mammography. From this group, 167 women were diagnosed with DCIS.
- MRI detected 92 percent of the DCIS, and mammography detected 56 percent cent of DCIS.
- When the DCIS was high grade, 98 percent were diagnosed by MRI and 48 percent were diagnosed by MRI alone.
Comments
MRI has the potential to expand the present ability of mammograms in the early detection of breast cancer. However, as the authors of this study support, more study is needed to understand how these results will apply to generalized screening in centers away from the academic setting of this study. Additionally, MRI has a high false positive rate, meaning that the technique can find changes in the breast that are not cancer. This can result in additional costs and sometimes invasive procedures. MRI is not available everywhere and is more expensive than mammograms. The technique also requires expertise to interpret and special equipment to perform.
While the results of this study are good news, we must wait until more results from future trials are available before MRI is recommended for routine screening.
Background Information
In Situ Carcinoma
Carcinoma in situ is a condition where large numbers of abnormal cells grow in the lobules or ducts of the breast. When the cells originate in the lobules, the condition is called lobular carcinoma in situ (LCIS). When the cells originate in the ducts, the condition is called ductal carcinoma in situ (DCIS).
Although the word "carcinoma" is used to describe them, the abnormal cells that define LCIS and DCIS are not fully cancerous because they have not developed the ability to invade tissue outside of the lobules or ducts. They are often referred to as precancerous conditions because they can either raise the risk of, or develop into, invasive cancer. (3)
Ductal Carcinoma In Situ (DCIS)
Unlike LCIS, DCIS often develops into invasive cancer, and the odds of this happening are high enough that the condition is almost always treated-- usually with surgery aimed at removing all of the DCIS, possibly followed by radiation therapy and hormonal therapy. In situ breast cancer rates have increased since 1980, largely because of the ability of mammography to find these changes before they can be felt. DCIS accounts for about 85 percent of the diagnoses of in situ breast cancers. (4)
MRI
Magnetic resonance imaging (MRI) uses magnetic fields to create an image of the breast. MRI is slightly more invasive than mammography because a contrast agent is injected before the procedure. At this time, MRI is most often used to help with the diagnosis and staging of cancer, rather than in the detection of cancer. However, the results from several clinical studies evaluating its use as a screening technique have shown that MRI also offers some benefit in the early detection of breast cancer, especially among certain groups of women at higher risk.(3)
Compared to mammography alone, MRI in combination with mammography has been shown to increase detection of cancer in women at higher risk due to a genetic mutation in the BRCA1 or BRCA2 gene or with a strong family history of breast cancer. (In general, a woman can be placed in the high-risk category if she has either a single factor that greatly increases her risk or a combination of lesser factors that together increase risk.) (3)
Sources:
1. A podcast of this information is available here: http://www.thelancet.com/audio
2. Christiane K Kuhl, et al, MRI for diagnosis of pure ductal carcinoma in situ:a prospective observational study. PP 485-492, www.thelancet.com Vol 370 August 11, 2007
3. Susan G. Komen for the Cure, www.komen.org
4. Breast Cancer Facts & Figure 2005-2006, "In situ Breast Cancer," American Cancer Society
