Doctors Flunk Genetic Testing, Report Finds

Additionally, the researchers found that nearly one-third of the physicians surveyed did not recognize the test's limitations and without intervention would have incorrectly interpreted the test results for their patients.

These findings, conducted by researchers at the Johns Hopkins Medical Institutions, are reported in the March 20, 1997 issue of the New England Journal of Medicine. "The survey confirmed our concerns that there were inadequacies in the genetic testing process," says Francis Giardiello, MD, associate professor of medicine and lead author of the study.

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 a particular laboratory (LabCorp) that provides 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 had valid indications for testing. Of the patients tested, only 19 percent received genetic counseling prior to testing and 17 percent 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.