Doctors who recommend genetic testing for healthy relatives of cancer patients overwhelmingly favor unnecessary, costly tests in a survey done in Texas.
The survey, conducted by a Baylor College of Medicine geneticist, found that most doctors given hypothetical situations recommended both a test when one wasn’t needed and choose the more comprehensive test when a simple one would have sufficed. This was the case regardless of the doctors’ specialty or experience.
"This demonstrates that most physicians aren’t informed how family-based genetic testing works," said Dr. Sharon Plon, director of the Baylor Cancer Genetics Clinic and the survey’s principal investigator. "They need help choosing the best test for cancer patient relatives."
The comprehensive test costs $3,340 on average. The simple test costs $475.
Genetic testing of mutations in two genes that raise the risk of breast and ovarian cancer, known as BRCA1 and BRCA2, began in 1995. It is drawing increasing interest because of new breast cancer treatment for women carrying harmful mutations of the genes.
Plon, whose survey appears this week in Genetics in Medicine, said she decided to conduct the research because she and her colleagues were seeing increases in referrals from physicians ordering comprehensive genetic tests and wanting help interpreting them. She also noted that the laboratory that performs the tests is marketing them directly to consumers.
A comprehensive gene test to look for BRCA1 and BRCA2 mutations is recommended for women with the cancers. But the National Comprehensive Cancer Network recommends that siblings and daughters of women with a harmful mutation of either gene receive a simpler test that looks only for the mutation identified in their families. It recommends no gene testing when the patient had a gene variant with uncertain significance.
Plon’s team randomly surveyed 225 Texas doctors from five specialties — family medicine, internal medicine, obstetrics and gynecology, general surgery and hematology and oncology - about whether and what kind of genetic testing they would order for healthy women 41 to 43 who have a relative with breast or ovarian cancer who tested positive for the gene. More than a third of the doctors said they had recommended genetic testing to patients.
When asked to consider a case in which a harmful BRCA1 mutation was found in a mother with cancer, only 20 percent of doctors appropriately chose for the healthy daughter the simpler test that looks for that same specific mutation.
About 82 percent of respondents recommended genetic testing when the gene variant showed no known increased cancer risk. The appropriate answer is that the women should not undergo genetic testing.
In all of the hypothetical questions, comprehensive testing was more commonly recommended than the simpler option. Only 2 percent of doctors correctly chose the cancer network’s recommended testing in all cases.
There was no statistical difference between doctors who had experience ordering BRCA tests and those who had no such experience. And while oncologists did the best of the five specialties, only 37 percent chose the simpler test.
Besides their eightfold greater cost, comprehensive tests are sometimes misinterpreted and prompt patients to undergo the surgical removal of breasts or ovaries for preventive reasons when that isn’t necessary.
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