Abstract
In this study, we evaluated the diagnostic value of the Dutch Clinical Genetic Center (CGC) referral guidelines for BRCA1/2 mutation testing in 903 early breast cancer patients, unselected for family history, diagnosed in a cancer hospital before the age of 50 years in 1974-2002; most prevalent Dutch pathogenic BRCA1/2 mutations had been analyzed on coded DNA in a research setting. Forty-nine (5.4%) of the patients were proven to be BRCA1/2 mutation carriers. We found that 78% and 69% of BRCA1 and BRCA2 mutation carriers identified met the criteria for referral to the CGC based on age, family history and synchronous multiple tumors; reflected by a combined sensitivity of 75.5% and specificity of 63.2%. More than half of the BRCA1 mutation carriers, that is, 58% had a triple-negative tumor. The highest AUC was obtained by shifting the age at diagnosis threshold criterion from 40 to 35 years and by adding a 'triple-negative breast cancer' criterion with an age threshold of 45 years; the specificity increased to 71.2%, whereas the sensitivity remained the same; that is, a referral of fewer patients will lead to the identification of at least the same number of BRCA1/2 mutation carriers. Two-thirds of the BRCA1/2 mutation carriers identified in this research setting had been referred for counseling and testing. Our results indicate that, awaiting a possibly more extended mutation screening of all breast cancer patients, the triple-negative status of a breast cancer should be added to the CGC referral criteria.