BRCA mutation carriers tend to develop breast cancer at a young age may have

Brca mutation carriers tend to develop breast cancer

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BRCA mutation carriers tend to develop breast cancer at a young age, may have bilateral breast cancer or have a personal history of both breast and ovarian cancer. There is also an increased risk for prostate and pancreatic cancer as well as male breast cancer in BRCA2 mutation carriers. The presence of two or more individuals in the family with breast cancer, of both breast and ovarian cancer in the family, breast cancer in one or more male family members, and one of more members with two primary cancers are features that increase the likelihood of hereditary susceptibility to breast and/or ovarian cancer. To
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4 estimate the probability of heritable genetic mutation in a family, one has to take into account the age of onset of breast cancer, the number of affected relatives, biological relationships of affected relatives, the ratio of affected to unaffected relatives as well as the presence/absence of associated malignancies and ethnic background. A distinct subtype of breast cancer called basal-like cancer has now been recognized and may be found in 80-90% of breast cancers arising in BRCA1 mutation carriers and in about 15% breast cancers with no family history. These cancers are usually triple negative (negative for the 3 predictive markers estrogen receptor, progesterone receptor and HER2 oncoprotein overexpression). Patients with basal-like cancer are usually younger, associated with poorer clinical outcome, more strongly associated with family history, more frequently “interval cancers” (i.e. cancers arising between annual mammograms), and with specific mammographic features demonstrating rapid progression. Likewise BRCA1 related ovarian cancers tend to be advanced stage high-grade serous carcinomas. Whilst all these features may suggest a stronger possibility of identifying a BRCA mutation, a blood sample is required for definitive genetic testing. Genetic testing aims at identifying the mutation that predisposes the individual or the family to cancer. In families where germ-line mutations in BRCA1 and BRCA2 have been identified, estimates for breast cancer risk can be made with greater accuracy. Both BRCA genes are very large genes. Several hundred different mutations have been identified but only a few of these mutations have been found repeatedly in unrelated families. Identification of a specific mutation in a family, therefore, is a complex process and must usually begin by testing a blood sample from a family member who has had breast or ovarian cancer, called “index" testing. If a specific mutation is identified through index testing, then "carrier" testing is possible for family members who wish to learn whether or not they have inherited that mutation and the associated cancer risks. A negative result from families where no mutation has been identified cannot exclude the possibility that other genes, as yet unknown, may be involved in that family.
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