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. Individuals are considered to be candidates for cancer risk assessment if they have a personal and/or family history (maternal or paternal lineage) with features suggestive of hereditary cancer. These features vary by type of cancer and specific hereditary syndrome. Criteria have been published to help identify families who may benefit from a referral to genetic counseling. The introductory sections of the PDQ (Cancer Genetics Risk Assessment and Counseling) cancer genetics information summaries on breast, ovarian, colorectal, prostate, skin, and medullary thyroid cancers describe the clinical features of hereditary syndromes associated with these cancers.
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 (e.g., mother, daughter, and sisters with breast cancer).
- Cancers occurring in multiple generations of a family (i.e., autosomal dominant inheritance).
- Occurrence of rare tumors (e.g., retinoblastoma, adrenocortical carcinoma, granulosa cell tumor of the ovary, ocular melanoma, or duodenal cancer).
- Unusual presentation of cancer (e.g., male breast cancer).
- Uncommon tumor histology (e.g., medullary thyroid carcinoma).
- Rare cancers associated with birth defects (e.g., Wilms tumor and genitourinary abnormalities).
- Geographic or ethnic populations known to be at high risk of hereditary cancers. Genetic testing candidates may be identified based solely on ethnicity when a strong founder effect is present in a given population (e.g., Ashkenazi heritage and BRCA1/BRCA2 mutations).
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 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 for family members.
A candidate for genetic testing receives genetic education and counseling before testing to facilitate informed decision making and adaptation to the risk or condition. Genetic education and counseling gives an individual time to consider the various medical uncertainties, diagnosis, or medical management based on varied test results, and the risks, benefits, and limitations of genetic testing.