MRI's high false positive rate has little impact on women's choice of preventive ...( Magnetic resonance imaging (MRI) fal...),Health

Magnetic resonance imaging (MRI) falsely detects breast cancer in five out of every six positive scans according to new research into the use of MRI for women with a high, inherited risk of developing the disease. However, this high rate of false positives does not have a major impact on a womans decision whether or not to have a prophylactic mastectomy.

The study, published today (Wednesday 26 March) in the April issue of the cancer journal, Annals of Oncology [1], also showed that MRI was very good at detecting genuine cases of invasive cancers and ductal carcinoma in situ (DCIS), a localised pre-cancer that can develop into invasive breast cancer, although the authors said that improvements in detection were still necessary.

The researchers from the Hereditary Cancer Clinic at Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands, followed 196 women with a BRCA1 or BRCA2 mutation, aged between 21 and 68 for an average of two years (a range of between one and nine years). Once the women had discovered that they carried a BRCA mutation (which gives a lifetime risk of breast cancer of up to 85 per cent and for ovarian cancer of up to 60 per cent) they made six-monthly visits to hospital to be examined by an experienced medical specialist and to have a mammography and, whenever possible, MRI. During their first surveillance visit, the researchers recorded whether the women had a preference for ongoing surveillance, or prophylactic mastectomy and/or a prophylactic salpingo-oophorectomy (removal of fallopian tubes and ovaries).

During the period of the study, which ran from 1999 to 2005, 41 per cent (81 of 196) of the women had at least one positive MRI or mammogram; breast cancer was detected in 17 women (11 from scanning, four during prophylactic mastectomy and two during the interval between surveillance visits). The researchers found that the sensitivity of mammography (the proportion of true positives) was 41 per cen
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