Role of the Genetic Counselor in Familial Cancer
Role of the Genetic Counselor in Familial Cancer
The authors offer a comprehensive overview of familial cancer risk counseling, providing both a general definition of this new genetic counseling specialty and specific components of the counseling process. Genetic counseling is, by and large, a referral service, and this is also true of cancer risk counseling. This places great importance on the health-care provider's ability to recognize families who may be at increased risk for an inherited form of cancer and should be referred for cancer risk counseling. It seems reasonable, therefore, to consider the issues relevant to making such a referral, including information on collecting an initial cancer history, strategies for handling a positive history, and the realities of DNA-based testing.
Collecting an Initial Cancer History
Obtaining an extensive family history of cancer is a key element in cancer risk counseling. However, taking an initial cancer history is equally important, as it provides the rationale for making the referral in the first place. Given the increasing options for DNA testing and surveillance available to individuals with known heritable cancer risks, health-care providers of cancer patients and their families should consider collecting initial family histories on a routine basis.
It is not uncommon for family histories to include one or more relatives who have been diagnosed with cancer. Yet only a subset of these families need to be referred to a cancer risk counselor. It is estimated that about 15% of total cancer cases are due to the presence of a germ-line mutation in a cancer susceptibility gene.
To help determine whether cancer risk counseling is warranted,
clinicians should collect the following
- The number of relatives affected with cancer, including the exact relationship of these relatives to the patient. (Patients may not recognize that multiple affected cases provide evidence for a familial cancer syndrome only if occurring in the same bloodline.)
- The specifics of each cancer diagnosis, particularly the site of origin and age of onset.
As stated in the article by Peters and Stopfer, it should be possible to elicit the above information by asking patients (or parents, if the patients are minors) a few simple questions. Patients can also be asked to check with relatives for verification of the cancer diagnoses and ages of onset. An alternative strategy would be to develop a brief cancer history questionnaire for patients to complete (either during their appointment or afterwards), which could then be reviewed and acted upon by clinic personnel.
Cancer histories suggestive of hereditary forms of cancer are likely to include at least some of the following features: two or more generations diagnosed with the same or related forms of cancer; cancers occurring at earlier than typical ages; the presence of rare tumors; and the presence of bilateral, multifocal, or multiple primary tumors in one or more family members .
Occasionally, the pattern of cancer within a family provides unequivocal evidence of a heritable factor. In general, however, cancer histories tend to be more difficult to interpret and require further documentation.
Strategies for Handling a Positive History
Initial family histories that reveal striking incidences of cancer can be handled in one of two ways: The health-care provider may choose to refer the patient to a center that offers familial cancer risk counseling or may prefer to continue working directly with the family.
The most difficult aspect of referring individuals for cancer risk counseling may be locating such a service. Questions about where to refer patients can be directed to the Genetics Division within one's hospital, the American Cancer Society, or the National Society of Genetic Counselors.
A cancer risk counselor can be a masters-level genetic counselor, an advanced practice oncology nurse, or another health-care professional. However, the number of professionals with training and experience in this area remains limited. For example, at present fewer than 100 masters-level genetic counselors specialize in cancer risk counseling. Some hospitals are meeting patient demands for detailed cancer risk and management information by setting up specialty clinics for individuals at increased risk for specific forms of cancer (most often, breast, colon, or ovarian cancer). At a clinic appointment, individuals may have the opportunity to meet with a team of health-care providers to discuss issues related to their increased cancer risks.
The further documentation of a family with a possible inherited form of cancer typically involves expanding the pedigree to four or more generations. Gathering this information usually requires discussions with multiple family members and the written documentation of as many cancer diagnoses as possible. These steps are critical, because the identification of a hereditary cancer syndrome may be based solely on the cancer history, and unfortunately, cancer history information provided by patients is notoriously inaccurate. Because documenting cancer diagnoses can be a daunting task, it is becoming standard practice to enlist motivated family members in these efforts. In fact, with the development of the 1993 Office for Protection from Research Risks (OPRR) guidelines protecting patient confidentiality, it is often easier for family members than for researchers to obtain this information .
Realities of DNA Testing
The availability of DNA testing for certain cancer susceptibility genes is seen as a motivating factor for patients to seek cancer risk counseling and the primary reason for the anticipated increase in demand. Prior to undergoing predisposition testing for a cancer susceptibility gene, it is important for patients to have realistic expectations of the testing process and to have considered the potential ramifications of learning their test results.
Only a handful of cancer susceptibility genes have been identified to date, and most of them are for rare cancer syndromes. Thus, DNA testing is only available to a limited number of families with positive cancer histories. In addition, there needs to be at least one living family member who has been diagnosed with cancer (or several members, if testing is to be accomplished via DNA linkage analysis), as it is necessary to document the presence of a germ-line mutation in the family. Although DNA analysis can be performed on tissue blocks, this method is more difficult, and most laboratories prefer working with blood specimens.
In addition, the search for a germ-line mutation in a cancer susceptibility gene is a labor-intensive, time-consuming project that can take several months. Patients need to be aware that the testing process, especially if performed on a research basis, may not be completed in a timely manner and, in fact, may not yield any results. Among families who have patterns of cancer consistent with a known cancer susceptibility gene, a certain percentage will not have identifiable mutations.
In addition to the laboratory issues, there are concerns about the potential harm of releasing this information to patients. Could a genetic testing result, if positive, be used to discriminate against the person in matters of health or life insurance, or in employment or educational situations? Sadly, discrimination on the basis of DNA results has been reported for other genetic diseases , and given society's fear of cancer, it is doubtful that the presence of a cancer-predisposing gene would be any less stigmatizing. There are also concerns that knowledge of one's gene status could engender depression and negatively influence family relationships and self-esteem. It is important for patients to be aware of these potential problems prior to initiating testing.
Until there is greater experience in providing DNA predisposition testing, such testing should be performed within a program that includes genetic education, informed consent, and psychological counseling. Thus, the need for experienced familial cancer risk counselors will only increase as DNA-testing options expand.
1. Schneider KA: Counseling about Cancer: Strategies for Genetic Counselors, 1994.
2. National Institute of Health, Office of Extramural Research, Office for Protection from Research Risks: Protecting Human Research Subjects: Institutional Review Board Guidebook, 1993.
3. Billings PR, Kohn MA, de Cuevas M, et al: Discrimination as a consequence of genetic testing. Am J Hum Genet 50:476-482, 1992.