Physicians need education in choosing the best gene test for cancer patient relatives
By Ruth SoRelle, M.P.H.
When a person is diagnosed with cancer – and particularly breast cancer – the immediate concern is whether it might be genetic. In other words, a woman might be afraid that her daughters or sisters face a risk as well.
Often, they take that question to their personal physicians. However, when Dr. Sharon E. Plon, director of the Baylor Cancer Genetics Clinic and her colleagues surveyed 225 physicians about the kinds of genetic testing they would offer women in such families, she found that they were unaware of guidelines for such tests.
"In the last several years, we have noticed an increase in referrals from physicians ordering comprehensive genetic tests and seeking help for interpretation of results," said Plon. "This made us curious as to how non-genetic physicians interpret familial genetic cancer history and ultimately make decisions about genetic testing."
Plon and her colleagues asked the doctors whether and what kind of genetic testing they would order for healthy women between the ages of 41 and 43 who had a relative with breast or ovarian cancer who had gene testing done already. Results were published recently in an online issue of Genetics in Medicine .
"What we observed in this study is that physicians are choosing more comprehensive testing for healthy relatives than current guidelines recommend, regardless of their experience or specialty," said Plon.
Current recommendations for genetic testing are made by the National Comprehensive Cancer Network.
In two of the presented cases, the patient with cancer had a known deleterious mutation in the BRCA1 gene that was associated with increased cancer risk. In two, the patient had a gene variant where there was uncertainty about the impact on breast or ovarian cancer risk.
A comprehensive gene test looking for mutations in the BRCA1 and BRCA2 genes that raise the risk of breast and ovarian cancer is recommended for women with the cancers.
However, the National Comprehensive Cancer Network recommends that healthy siblings and daughters of women found to have a deleterious BRCA1 or BRCA2 mutation receive a simpler gene test that looks only for the mutation identified in their families. It recommends no gene testing when a patient has a variant with uncertain significance.
In the survey, when the physicians considered a case in which a deleterious BRCA1 mutation was identified in a mother with cancer, 98 percent recommended a genetic test, but only 20.4 percent chose the simpler option that looks for the specific mutation found in the mother. In two cases where the gene variant with no known increased cancer risk was found, approximately 82 percent of physicians recommended genetic testing. The comprehensive genetic testing was more commonly recommended in all cases than the simpler option. Only 2 percent of physicians chose the Network's recommended testing in all cases.
"In both situations, the comprehensive test was selected most with an almost nine-fold increase in unnecessary genetic testing cost across all cases," said Plon. The comprehensive genetic test costs $3,340 on average as opposed to $475 for the simpler option. In two cases, no gene testing at all is recommended.
Survey to assess current recommendation
In the second part of the survey, physicians answered questions about their own experience and education with genetic testing.
"There was clear misunderstanding about the differences in single site testing and comprehensive testing," said Plon. "This is an important area where using genetic professionals would be beneficial."
"Utilization of genetic professionals is a requirement in other countries," said Plon. "It's not in the United States and one reason has been the potential increase in cost by involving genetics professionals. We find involving them may actually save on overall costs, by decreasing the ordering of more expensive test or no test if necessary."
Risk management recommendations
On the other hand, physicians appropriately suggested more intense screening for healthy women with the deleterious BRCA1 mutation than for those with the variant of uncertain significance – although they suggested more intense surveillance in both groups than for women who had not had gene testing.
They were more likely to suggest ovary removal (63 percent) in women with the deleterious BRCA1 mutation than in women with the variation of uncertain significance (13 percent). They suggested regular breast MRI in women with the deleterious BRCA1 mutation more often (76 percent) than in women with the variation (38 percent). However, the suggestions for relatives with a variant were still more intense than a similar woman with no testing.
"This is actually quite positive," said Plon. "Overall, the majority of physicians understood that women with the deleterious mutation need more risk management, but education is still needed to improve the management of women with variants."
