BRCA1 mutations found in archived early onset breast tumours

Inherited mutations in the BRCA1 gene are thought to account for approximately 5% of breast cancers in women under the age of 45 years. In order to determine whether mutations could be found at the expected frequency, 60% of the protein coding region of BRCA1 was screened in 75 archived early-onset breast tumours, taken from women under 45 years of age. Two of the 75 tumours (2.7%) had detectable mutations, in close agreement to that predicted. Since BRCA1 mutations found in breast tumours are invariably germline, two immediate consequences are apparent. Firstly, family members of affected patients are likely to carry mutations as well, and should be considered for BRCA1 screening; and secondly, persons harbouring a germline BRCA1 mutation should be examined frequently and indefinitely for new primary tumours in remaining breast tissue.