Breast Carcinoma Flashcards
About half of women with hereditary breast cancer have mutations in which gene?
BRCA1 (on chromosome 17q21.3). An additional one-third have mutations in BRCA2 (on chromosome 13q12-13).
Name a few less common genetic diseases associated with breast cancer.
- Li-Fraumeni syndrome (caused by germ-line mutations in p53)
- Cowden disease (caused by germ-line mutations in PTEN)
- Carriers of the ataxia-telangiectasia gene
What are some non-genetic risk factors for breast cancer?
- Prolonged exposure to exogenous estrogens postmenopausally (i.e., hormone replacement therapy) to prevent, or at least delay, the onset of osteoporosis
- Oral contraceptives (controversial)
- Ionizing radiation to the chest
- Many other less well-established risk factors, such as obesity, alcohol consumption, and a diet high in fat
Overexpression of the HER2/NEU proto-oncogene has been found in up to what percentage of invasive breast cancers?
Up to 30%. This gene is a member of the epidermal growth factor receptor family, and its overexpression is associated with a poor prognosis.
In addition to those producing the well-established familial syndromes, which other genetic changes have been implicated in the genesis of sporadic breast cancer?
Amplification of RAS and MYC genes has been reported in some human breast cancers. Mutations of the well-known tumor suppressor genes RB and p53 may also be present. Furthermore, a large number of genes including the estrogen receptor may be inactivated by promoter hypermethylation.
What are the five subtypes into which gene expression profiling can stratify breast cancer?
- Luminal A (estrogen receptor positive)
- Luminal B (estrogen receptor positive)
- HER2/NEU overexpressing (estrogen receptor negative)
- Basal-like (estrogen receptor and HER2/NEU negative)
- Normal breast like
What percentage of breast cancers are related to specific inherited mutations?
About 5-10%.
