To print: Select File and then Print from your browser's menu --------------------------------------------------------------------------------------- Title: ASCO: Magnetic Resonance Imaging Finds Missed Breast Cancers, But at a High Cost in False Positives URL: http://www.pslgroup.com/dg/2340C6.htm Doctor's Guide June 2, 2003
By Bruce K. Dixon CHICAGO, IL -- June 2, 2003 -- Magnetic resonance imaging (MRI) is a sensitive screening tool that may detect mammographically occult disease in women at high risk of breast cancer, according to a study presented June 1st at the 39th Annual Meeting of the American Society of Clinical Oncology. However, say researchers from Memorial Sloan-Kettering Cancer Center, in New York, MRI also yields a significant number of false-positive results that lead to additional examinations, leading to psychological stress in these women, who are already anxious about their elevated risk of breast cancer. Study leader and presenter Mark Robson, MD, said he and other researchers have been intrigued by the theoretical advantages that breast MRI offers as an adjunct to mammography in women at high risk of developing breast cancer. "A number of studies have demonstrated [MRI's] improved sensitivity compared to mammography in the research setting, and MRI has the added advantage of not requiring ionizing radiation, reducing the theoretical risk of radiation-induced breast cancer." Disadvantages of MRI, said Dr. Robson, include the need for specialised equipment to biopsy lesions that are not discernible by mammography or ultrasound, and specificity appears to be relatively poor in the research setting. Also, the exam is costly and may induce patient discomfort. "Despite these limitations, several centers, including our own, have begun to incorporate MR screening for surveillance of women at the highest levels of risk for breast cancer," Dr. Robson said. To assess the value of MRI in a clinical setting, Dr. Robson and his team enrolled 53 women with documented deleterious germline BRCA mutations. The women underwent 115 breast MRI examinations, of which 90 were screening and 25 were interval follow-up, between 1998 and 2002. Medical records and radiology reports were reviewed to determine clinical outcomes. The results show that 53 of the women underwent 90 screening examinations and 25 recommended interval follow-up studies. Two women (3.8%) were diagnosed with ductal carcinoma in-situ – one case of which was mammographically occult -- following an abnormal MRI. Further studies, biopsy, or short interval follow-up were recommended after 43 (37.4%) of 115 studies, and 35 (40%) of 90 of screening studies. Tissue sampling was performed in 12 cases, 2 of which yielded malignancy, for a positive predictive value of 16.7%. Sensitivity and specificity were 100% and 81%, respectively, in women undergoing screening examinations. "This experience indicates that breast MRI is a sensitive screening technique that can identify interval breast cancers in women at hereditary risk," said Dr. Robson. "The relative effects of MRI compared to more frequent mammography or interval breast sonography are not defined by this study, but MRI does have the ability to identify…cancers that are not recognised by these other techniques." "At present, however, specificity of breast MRI in a clinical as opposed to a research setting is sub-optimal," he cautioned. "In this report, 36% of scheduled screening examinations resulted in a recommendation for either short-term interval follow-up or a biopsy. This compares to a reported rate of about 6.5% to 10% for examinations with mammographic screening. Frequent recommendations for biopsy after interval follow-up have adverse psychological consequences for women at the highest level of [breast cancer] risk and may alter their decision-making regarding prophylactic mastectomy," Dr. Robson said. "For these reasons, while screening MRI may be reasonable to offer women with a genetic predisposition for breast cancer, the pros and cons of the procedure should be discussed in detail before the study is performed, and the exam should be interpreted by radiologists with significant experience -- and preferably specific training -- in this technique," he concluded. [Study title: Breast Cancer Screening Utilizing Magnetic Resonance Imaging (MRI) in Carriers of BRCA Mutations. Abstract 362] --------------------------------------------------------------------------------------------- Copyright © 1999 P\S\L Consulting Group Inc. All rights reserved. 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