Germ-line BRCA1 mutations in women with sporadic breast cancer:: Clinical correlations

Purpose: Sporadic nonhereditary breast cancer is recognized as the most common form of this malignancy. Presence of germ-line mutations in the BRCA1 gene of these tumors is an infrequent event. We undertook the present study to evaluate the prevalence of germ-line mutations in patients diagnosed with sporadic breast cancer, and to delimit the clinical spectrum of this subgroup of patients with germ-line mutations and their differences with respect to patients with no evidence of BRCA1 gene mutations. Methods: We studied 105 patients diagnosed with breast cancer, selected from among our living patients; those with carcinoma-in-situ and those with a definite family history of breast or ovarian cancer were excluded. Genomic DNA, obtained from peripheral-blood lymphocytes, was studied for BRCA1 mutations by polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) and direct DNA sequencing. Fourteen clinicopathologic parameters were analyzed in each patient. Results: Six (5.7%) frameshift mutations that corresponded to truncating proteins and three missense mutations, the functional meaning of which remains speculative, were identified. The patients with germ-line mutations were found to have a more advanced age at diagnosis, as well as a longer median survival (51 months). Conclusion: Women with sporadic breast cancer of late onset may display a significant incidence of germline BRCA1 mutations, which occur at a rate not previously determined in this group of patients. The presence of variations in the sequence of the BRCA1 gene could influence the longer survival observed in these patients. (C) 1998 by American Society of Clinical Oncology.