Breast Cancer Screening Results Worse With BRCA1 Mutation

Other hereditary breast cancers easier to find, but overall survival good

THURSDAY, Nov. 18 (HealthDay News) -- Among hereditary breast cancers, those with BRCA1 mutations are less likely to be detected mammographically and more likely to be larger than 1 cm when detected, according to research published online Nov. 15 in the Journal of Clinical Oncology.

Adriana J. Rijnsburger, M.D., of Erasmus Medical Center in Rotterdam, Netherlands, and colleagues analyzed the long-term results of the Dutch MRI Screening Study (started in 1999) on early detection of hereditary breast cancer. Study participants were women with higher than 15 percent cumulative lifetime risk (CLTR) of breast cancer who were screened with annual mammography and magnetic resonance imaging (MRI) and stratified by subgroups: carriers of a gene mutation (50 to 85 percent CLTR), and two familial groups with high risk (30 to 50 percent CLTR) or moderate risk (15 to 30 percent CLTR).

The researchers found that MRI sensitivity was significantly better than mammography for detection of invasive cancer (77.4 versus 35.5 percent), but not for ductal carcinoma in situ (DCIS). Compared to the high-risk, moderate-risk, and BRCA2 groups, results for the BRCA1 group were worse for mammography sensitivity, tumor size of 1 cm or less at diagnosis, proportion of cancers which were DCIS, and younger age at diagnosis. Six-year distant metastasis-free and overall survival in all 42 BRCA1/2 mutation carriers with invasive breast cancer were 83.9 and 92.7 percent, respectively, and 100 percent in the familial groups.

"In conclusion, the update of our study confirms that, with a longer follow-up period (approximately five years) the sensitivity of MRI is still strongly superior to that of mammography," the authors write. "In addition, and most strikingly, BRCA1-associated tumors behave completely differently from BRCA2-associated tumors and those from the other risk groups in view of the younger age at diagnosis, lower mammographic sensitivity, the high proportion of interval cancers, the low proportion of DCIS, and unfavorable tumor size at diagnosis."

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