By Sean Henahan, Access Excellence

LOS ANGELES- The development of a genetic test for determining breast cancer risk highlights a number of the medical and ethical issues that are bound to become more pressing as the number of genetic tests for different cancers proliferate, reported researchers at the annual meeting of the American Society of Clinical Oncology.

Last year researchers announced data linking mutations in the BRCA1 gene to rare familial forms of breast and ovarian cancer. Subsequent studies showed that the BRCA1 gene also appears to play a role in much more common types of non-inherited breast cancers. These discoveries gave researchers the ability to test for these gene mutations, but did not tell them how to use the test.

Physicians are now facing a number of questions, including: who should be tested; how should the information be used to mange the patient; what are the tests really saying about level of risk; and what are the associated costs of testing and counseling at risk patients. Privacy issues, ability to retain insurance and employment security are also important issues, noted Judy Garber, M.D., M.P.H., Director, Cancer Risk and Prevention Clinic, Dana-Farber Cancer Institute, Boston, MA

Dr. Garber is studying the implications of genetic testing for breast cancer susceptibility (such as BRCA1). The patients who might benefit most from BRCA1 testing have not yet been identified, she notes. Researchers will have to determine how to use the test results once they get them. Also, women from families in which the BRCA1 mutation is present but who do not have the mutation themselves are also not free of risk and will require ongoing surveillance, she notes.

Women who do have the BRCA1 gene will face a number of difficult choices. While there are numerous screening tests to look for early signs of breast and ovarian cancer, there is some debate about what measures can be taken to prevent these cancers from developing in at risk patients. Both physicians and patients will have to consider issues regarding the frequency of mammograms, physical examinations and tests such as the CA-125 blood test that can detect early biochemical changes associated with cancer growth.

Despite the significant interest of people from high risk cancer families, it remains to be seen how many will opt for testing as it becomes more widely available. The most data available on predisposition testing is in the area of Huntington's disease. Cancer doctors are hoping that experience with this disease may provide some insight into the issues associated with genetic testing for cancer.

A genetic test for Huntington's disease became available recently. The test can tell with certainty if an individual is a carrier for the Huntington's disease gene and whether that person will develop the disease. The problem is, there is currently no treatment for Huntington's disease.

Far fewer individuals at risk for Huntington's disease have come forward for genetic testing than was predicted. Before the test became available, surveys suggested that as many as 80% of people at risk would participate in testing. However, since the test has become available, less than half of those who could participate in screening have done so.

The benefits of the Huntington's test are mainly psychological. The test is definitive, which provides some relief from uncertainty, and may helps people, regardless of the results, better prepare for the future.

Genetic testing for cancer susceptibility is a different matter. For one thing, a test showing that a person has a certain gene defect shows an increased chance, not a guarantee, that the person will develop cancer. Also, the person could still be at some risk for a type of cancer, even if the gene defect is not present.

The big difference between cancer and Huntington's disease is that preventive and therapeutic strategies do exist for a number of cancer types. The presence of a predisposing gene could alert physicians to conduct more frequent screening for early signs of breast cancer for example, or could prompt dietary changes in a person with an increased chance of colon cancer.

Breast cancer may be too complex a disorder for many women to derive benefit from genetic testing, according to another researcher, Funmi Olopade, M.D., Director, Cancer Risk Clinic, University of Chicago, IL.

Dr. Olopade and colleagues analyzed the family histories of 97 women who came to the clinic for breast cancer risk assessment. The researchers found a wide variety of familial breast cancer syndromes among 1599 female members of these patients' families.Forty-six families had pedigrees consistent with identifiable hereditary breast cancer syndromes. Another 36 families had pedigrees consistent with familial breast cancer which did not meet the criteria for known syndromes, and 15 families had no obvious pattern of inheritance.

Only eight percent of these high risk families might have benefited from BRCA1 testing, noted Dr. Olopade, who based this conclusion on age and family pedigree data. The studies of these families showed how complex are the patterns of cancer inheritance. Many of the women also appeared to be at increased risk of other forms of cancer.

"Genetic tests alone for cancer-related mutations are rarely sufficient for determining levels of cancer risk. For women at risk for malignancies other than breast cancer, a negative test would be falsely reassuring. In addition, people who are tested and found to have a cancer-related mutation will require considerable resources, including counseling and guidance, in establishing a plan to reduce cancer risk or ensure early detection," noted Dr. Brian Leyland-Jones, Chairman, department of clinical oncology, McGill University, Montreal, Quebec, Canada.

Another potential problem is that even people in very high-risk family groups may be reluctant to receive genetic testing and counseling. A study from Dana-Farber Cancer Institute in Boston, MA, showed a varied amount of interest in genetic testing in members of families at risk for Li-Fraumeni Syndrome (LFS). Lifetime risk for numerous cancers including breast cancer, brain tumors, and leukemia are as high as 90% in the group of people.

The Dana-Farber researchers offered a program of genetic counseling, medical consultation and psychological assessment to 52 family members considered at risk for LFS. Only 21% accepted the offer, and another three percent expressed interest. The remainder declined the offer or postponed the decision to participate.

Age played an important role in the decision to participate, reported Dr. Andrea Patenaude, director of Psycho-oncology Research at Dana-Farber. The average age of those declining counseling was 52 years, while the age of those accepting the offer averaged 33 years. Some of those who declined said they were concerned about losing their insurance, while others feared a negative result form the tests. Those who did undergo the counseling cited a desire to know their genetic risk level and the potential risks for their children.

"The true value of advances in genetic testing will be known only when it is combined with genetic counseling to educate at-risk individuals so informed decisions can be made. Genetic testing is not a benign intervention. Participants may require time to ponder the pros and cons. Different strategies may be needed to approach participants at different ages, noted Dr. Leyland-Jones.

"What is new for oncologists are the implications of genetic testing for family members as well as patients. Physicians must plan carefully to handle BRCA1 testing and the results of the testing. Policies will have to be in place to safeguard the insurability of patients and other potential consequences of disclosure, both intentional and inadvertent," he emphasized.

For more information on the studies cited in this article see the May 1995 issue of The Journal of Clinical Oncology.