Promoter methylation of BRCA1 was assessed in 851 archived tumor tissues collected from a population-based study of women diagnosed with invasive or in situ breast cancer in 1996-1997, and who were followed for vital status through the end of 2002.
To better define the role of: (1) a family history of breast and ovarian cancer and (2) the cancer susceptibility genes, BRCA1 and BRCA2, in the development of BCIS.
Ninety-five per cent of the epithelial ovarian cancers occurred in BRCA1 mutation carrying women versus 38% of infiltrating breast cancers and 7% of carcinoma in situ of the breast.