Breast surgeons can and should provide genetic counseling to their patients because the need outstrips the availability of genetic counselors.
Breast surgeons can and should provide genetic counseling to their patients because the need outstrips the availability of genetic counselors, Patrick W. Whitworth Jr., MD, of the Nashville Women’s Center in Nashville, Tennessee, said at the 34th Annual Miami Breast Cancer Conference, held March 9–12 in Miami Beach, Florida.
“They can provide genetic counseling and already do provide genetic counseling--and they must provide genetic counseling,” Whitworth said. “This is an urgent problem and gigantic unmet need.”
Of more than 35,000 breast cancer patients with deleterious BRCA mutations, less than a third have been identified. Of the 220,000 unaffected BRCA mutation carriers in the US, only 5% to 6% have been identified, he noted.
“This is a public health failure and a real disaster,” Whitworth said.
Negative findings can spare patients of unnecessary interventions like other testing and surgery, while positive findings can prompt MRI surveillance and prevention efforts. Genetic testing also helps providers and payers to better allocate resources, reducing waste associated with unnecessary tests and procedures, for example.
“We’ve all seen people who want a preventative mastectomy,” Whitworth said. “Half of them who are tested are negative-but it’s hard to back them down from the worry they’ve been living with.”
Identifying carriers does not just affect that one patient, he emphasized. “Their families can also get tested,” he said. Half will be “off the hook.”
Soon after Myriad’s BRCA patents were struck down in court, there was a race to develop new genetic risk assays. Now, instead of 2-gene assays, panels involve 30 or more genes-and testing has become much more affordable, dropping from initial costs of $4,000 per test to $300, Whitworth noted.
Along with more complex panels, understanding of breast cancer genetics has also changed over recent years. Most breast cancer-related gene mutations involve DNA repair genes, like the so-called DNA mismatch repair “Lynch genes” that correct DNA replication errors.
“The other thing we’re becoming aware of is that it’s not ‘one gene, one cancer’,” Whitworth said.
Multiple cancers can be associated with a single-gene mutation, and multiple genes can be associated with a single cancer type.
“A number of these genes are not high penetrance,” he noted. “They’re moderate-penetrance genes.”
In 25-gene panels, 10.7% have deleterious mutations, including 6% who are carrying BRCA1/2 mutations but also 4.6% with non-BRCA mutations. Whereas young age, Ashkenazi ancestry, and family history predict deleterious BRCA mutations, these factors do not seem to be associated with other, non-BRCA deleterious mutations, Whitworth cautioned.
“They’re no good at all at predicting these moderately-penetrant genes,” he said.
There is already “dramatically inadequate” testing for BRCA, with only up to 6% of BRCA carriers identified. With expanded availability of low-cost, multi-gene-and even whole-exome-testing, there simply won’t be enough genetic counselors to meet demand in a timely manner.
The solution is for educated physicians to offer their patients genetic counseling with genetic counselors playing a support role, he suggested.
“It’s an emergency,” Whitworth said. “We all need to keep up.”
Critics of that idea have questioned whether nongenetic specialists will properly order and interpret tests and adequately counsel patients, he acknowledged. But there are increasingly available online risk-assessment tools that can help with interpretation and counseling, he noted.
“There is tremendous support for cancer surgeons to get these things done and to do them well,” Whitworth said.
No action is warranted when gene panels yield variants of unknown significance (VUS), he emphasized.
“No action should ever be taken on the basis of VUS, in any case, at any time,” he said. “No action is needed. Don’t burden your patients with that information.”