"This study is unique because it is one of the first to evaluate the use of a gene test in the commercial setting," says Francis Giardiello, MD, associate professor of medicine and lead author of the study. "Before genetic testing for cancer susceptibility became available commercially, the tests were offered in a research environment and delivered according to controlled protocols. Because many patients are now receiving the test from their personal physicians however, we were interested in how well patients not involved in research programs were being informed of the benefits and limitations of the test," says Giardiello. "The survey confirmed our concerns that there were inadequacies in the genetic testing process."
Patients involved in this survey were tested for a mutation of the APC gene, a tumor suppressor gene found to be linked to colon cancer by Hopkins researchers in 1991. A positive test for an APC gene mutation indicates that the affected individual has an inherited genetic condition called familial adenomatous polyposis (FAP). This condition is characterized by the formation of hundreds of polyps in the colon. If prophylactic surgery is not performed, nearly all patients with FAP go on to develop colorectal cancer later in life.
To assess the test's use, the Hopkins researchers conducted phone interviews with physicians and/or genetic counselors who had ordered the test through LaboratoryCorporation of America (LabCorp). The Johns Hopkins University has a service contract with LabCorp to provide guidance to physicians concerning test interpretation, patient education and counseling. Information gathered as a result of these activities allowed the researchers to assess the test in three areas: 1) validity of test indications 2) provision of formal pre-test genetic counseling and written informed consent of the patient, and 3) understanding by providers of the test results.
The Hopkins researchers found that of the 177 patients who received testing, 83 percent (147) had valid indications for testing, which included having symptoms of FAP or being a first-degree relative of FAP-affected patients. Of the patients tested, only 19 percent (33) received genetic counseling prior to testing and 17 percent (28) gave their written informed consent to have the test performed. Furthermore, in 32 percent of the cases, the physicians did not know how to interpret the test results.
Based on these findings, researchers recommended that a comprehensive approach to patient counseling and education be universally implemented. "Physicians who plan to order this test for their patients must be prepared to offer or arrange for genetic counseling for their patients," says Jill Brensinger, MS, a genetic counselor with the Hereditary Colorectal Cancer Registry at Johns Hopkins and co-investigator of the study. "Patients need to know that a positive test result indicates the need for routine colon surveillance, eventual prophylactic surgery and possible discussions on family planning. Additionally, physicians need to be educated that a test reporting that no mutation was found could be a false negative if no mutation was previously detected in another family member," says Brensinger. "If patients are not informed of this possibility, they may not adopt the appropriate surveillance practices and their disease will not be detected in its earliest stage."
Familial adenomatous polyposis affects one of every 8,000 individuals, accounting for about one percent of all colon cancers. Approximately 131,000 new cases of colon cancer will be diagnosed in the U.S. this year alone. An additional 37,000 will die from the disease. It is the third most common cancer diagnosed in both men and women.
In addition to Giardiello and Brensinger, other participants in this research study include Gloria M. Petersen, PhD, Michael C. Luce, PhD, Linda M. Hylind, BS, RN, Judith A. Bacon, BS, Susan V. Booker, BA, and Rodger D. Parker, PhD, Stanley R. Hamilton, MD.