Association of BRCA1 germline mutations in young onset triple-negative breast cancer (TNBC)

BRCA1-associated breast cancers have been associated to a triple-negative phenotype. The prevalence of BRCA1 germline mutations in young onset TNBC based on informativeness of family history has not been reported.

From January 2008 to May 2009 were collected blood and tumor samples from patients with TNBC younger than 50 years and without a family history of breast and ovarian cancer in first- and second-degree relatives. Analysis of BRCA1 germline mutations was made. Age at diagnosis and informativeness of family history (presence of female in first- and second-degree relatives alive until age 45) was collected in all cases. Immunohistochemistry of basal-like features was performed centrally in all available tumors.

Seven pathogenic mutations were detected in 92 patients (7.6 %), two of them in patients younger than 35 years (28.6 %) (Fisher's exact test, p = 0.631). Three non-classified variants were detected (3.2 %). Family history was informative in two patients with a pathogenic mutation (28.6 %) and not informative in five (71.4 %) (Fisher's exact test, p = 0.121). Of the seven patients with a pathogenic mutation, four had a basal-like phenotype.

Patients with apparently sporadic TNBC younger than 50 years and a non-informative family history are candidates for germline genetic testing of BRCA1.