According to the National Cancer Institute, breast cancer is the second most common cancer in women after skin cancer, in the U.S. It can occur in both men and women, although very rare in men. Each year there are about 2,300 new cases of breast cancer in men and about 230,000 new cases in women.
A woman’s lifetime risk of developing breast and/or ovarian cancer is greatly increased if she inherits a harmful gene mutation in BRCA1 or BRCA2. A harmful BRCA1 or BRCA2 mutation can be inherited from either parent. Each child of a parent who carries a mutation in one of these genes has a 50% chance (1 in 2 chances) of inheriting the mutation. The effects of mutations in BRCA1 and BRCA2 are seen even when the second copy of the gene is normal.
The following are features that suggest hereditary cancer:
- Unusually early age of cancer onset (e.g., premenopausal breast cancer).
- Multiple primary cancers in a single individual (e.g., colorectal and endometrial cancer).
- Bilateral cancer in paired organs or multifocal disease (e.g., bilateral breast cancer or multifocal renal cancer)
- Clustering of the same type of cancer in close relatives
- Cancers occurring in multiple generations of a family
- Occurrence of rare tumors (e.g., adrenocortical carcinoma, pheochromocytoma, paraganglioma)
- Unusual presentation of cancer
- Uncommon tumor histology (e.g., medullary thyroid carcinoma)
- Rare cancers associated with birth defects (e.g., Wilms tumor and genitourinary anomalies)
- Cancer coupled with an ethnic background known to be at increased risk of hereditary cancers. Genetic testing candidates may be identified based solely on cancer history and ethnicity (e.g., Ashkenazi Jewish ethnicity and BRCA1/ BRCA2 mutations).
Genetic counseling is defined by the National Society of Genetic Counselors as the process of helping people understand and adapt to the medical, psychological, and familial implications of genetic contributions to disease.
As part of the process of genetic education and counseling, genetic testing may be considered when the following factors are present:
- An individual's personal history (including health history, clinical characteristics, and ethnicity) and/or family history is suspicious for a genetic predisposition to cancer.
- The genetic test has sufficient sensitivity and specificity to be interpreted.
- The test will impact the individual's diagnosis, cancer management or cancer risk management, and/or help clarify risk in family members.