Experts recommend offering genetic testing when a risk assessment suggests the presence of an inherited cancer syndrome for which specific genes have been identified. The American Society of Clinical Oncology (ASCO) Policy Statement on Genetic Testing for Cancer Susceptibility proposes that genetic testing be offered when the following conditions apply:
An individual has a personal or family history suggestive of a genetic cancer susceptibility syndrome.
Characteristics used in making this determination are discussed in the PDQ summaries on the genetics of specific cancers. Even when individual and family history characteristics indicate a possible inherited cancer syndrome, individuals may elect not to proceed with testing after discussion of potential risks, benefits, and limitations, as discussed below. Conversely, individuals whose pedigrees are incomplete or uninformative due to very small family size, early deaths, or incomplete data on key family members may elect to pursue genetic testing in an attempt to better define their risk status. In these situations, it is particularly important that the pretest counseling fully explore the limitations of the testing process.
In 2010, ASCO updated its policy statement to address testing for low- to moderate-penetrance genes, multiplex genomic tests, and direct-to-consumer (DTC) testing. This current ASCO framework (Table 1) recommends that the provider consider the evidence for clinical utility of the test in addition to whether the test was obtained through a health care provider or directly by the consumer.
Table 1. Clinical Utility of Genetic/Genomic Testsa
Low- and moderate-penetrance gene mutations (e.g.,CHEK2)
High-penetrance gene mutations (i.e.,BRCA1,BRCA2)
Low- and moderate-penetrance gene mutations
ASCO's position is that when a test, regardless of clinical utility, is ordered by a health care professional, the provider is responsible for organizing follow-up care based on the findings. For tests that were ordered by the consumer without health care professional involvement, management decisions are based on the evidence for clinical utility. For tests with accepted clinical utility, follow-up care can be guided by the evidence for cancer risk associated with the genetic test finding. However, in tests ordered by the consumer that have uncertain clinical utility, ASCO recommends that follow-up care consist of education regarding the lack of evidence regarding the test's clinical utility and that cancer risk management decisions be guided by established cancer risk factors.
Genetic education and counseling, including the interpretation of genetic test results, will vary depending on whether a previous attempt at genetic testing has been made (see Figure 2). In general, there are two primary circumstances in which genetic testing is performed:
Families with evidence of an inherited susceptibility that have not had any genetic testing or in which genetic testing has not identified a mutation.