Breast cancer type 1 (BRCA1) and breast cancer type 2 (BRCA2) susceptibility proteins are normally expressed in breast tissue, where they help repair damaged DNA or destroy cells if the damaged DNA cannot be repaired. Those with genetic defects or mutations of the BRCA1 or BRCA2 genes are predisposed to developing breast or ovarian cancer. Studies have shown that carriers of the BRCA1 gene have as high as an 85% risk of developing breast cancer and a 45% risk of developing ovarian cancer by age 85.2
BRCA determination is typically performed on blood or saliva samples, which contain the DNA necessary to perform the genetic analysis. Detection of positive mutations create dilemmas for patients, as decisions must be made as to the course for prevention. In some cases, especially where family history prevails, preventive mastectomy or ovarectomy are performed to reduce the risk of developing cancers in the target organs or tissues.
While not a TRUE tumor marker in the sense that BRCA is NOT detecting the growth of a malignant tumor, it has been included here since it has been used as a screening tool to assess those at risk for developing specific cancers.