Many of the medical and scientific terms used in this summary are found in the NCI Dictionary of Genetics Terms. When a linked term is clicked, the definition will appear in a separate window.
This summary describes current approaches to assessing and counseling people about their chance of having an inherited susceptibility to cancer. 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. Several reviews present overviews of the cancer risk assessment, counseling, and genetic testing process.[1,2,3,4]
Clinical validity refers to the predictive value of a test for a given clinical outcome (e.g., the likelihood that cancer will develop in someone with a positive test). It is primarily determined by the sensitivity and specificity with which a test identifies people with a defined clinical condition within a given population. Sensitivity of a test refers to the proportion of people who test positive for a clinical condition among those who actually have the clinical condition; specificity refers...
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.[2,6] The PDQ cancer genetics information summaries on breast, ovarian, colorectal, prostate, and skin cancers and endocrine and neuroendocrine neoplasias describe the clinical features of hereditary syndromes associated with these conditions.
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).
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/BRCA2mutations).[7,8]