This article has been updated to reflect current testing guidelines.
NEW YORK (GenomeWeb) – Surgeons' opinions of genetic testing influences whether their breast cancer patients receive testing, a new study has found.
About a third of patients diagnosed with breast cancer receive genetic testing after their diagnosis, a decision that could be swayed by their surgeons.
Researchers led by the University of Michigan's Steven Katz surveyed more than 7,800 women with breast cancer and nearly 400 surgeons. They asked the patients about their cancer treatment and surgeons, and asked the surgeons about the frequency at which they refer patients for genetic testing and how confident they felt in discussing testing.
As they reported today in JAMA Surgery, the researchers estimated that the attending surgeon accounts for about 17 percent of the variance in testing.
"The surge of genetic testing in cancer care is a major challenge for surgeons," Katz, the study's senior author, said in a statement. "There is a lack of consensus around guidelines and approach to testing, and legitimate uncertainty about its value in guiding treatment, especially with newer genes whose cancer risks are not well defined."
The researchers drew on surveys sent to 7,810 iCanCare study participants, which includes women diagnosed with stage 0 to stage 2 breast cancer who are part of the Surveillance, Epidemiology, and End Results (SEER) registries in Georgia or Los Angeles County. More than 5,000 patients, about 70 percent, responded to the survey.
Overall, 27 percent of patients underwent genetic testing, including a third of the women who had an elevated pre-test risk of harboring a mutation and 14 percent of women with average pre-test risk. Guidelines recommend that breast cancer patients with a higher risk of a genetic mutation due to family history or other factors undergo testing, the researchers noted.
While patients' pre-test risk explained about 20 percent of the variability of getting genetic testing, who their surgeon was also had a role in whether they received testing.
In their survey response, 98 percent of patients identified who their surgeon had been and the researchers surveyed those surgeons about their attitudes toward genetic testing. They scored the surgeons' responses on a measure they developed, called the Surgeon Tendency to Order Genetic Testing Scale.
Some surgeons, the researchers found, were more likely than others to order genetic testing, even if patients had the same level of risk.
If a patient with a higher pre-test risk saw a surgeon who fell in the 5th percentile of test-ordering, she had a 26 percent probability of receiving testing, but if she saw a surgeon who fell in the 95th percentile, she had a 72.3 percent probability of undergoing testing. Meanwhile, an average-risk patient had a 4 percent probability of being tested if she saw a 5th percentile surgeon and a 24 percent probability of undergoing testing if she saw a 95th percentile surgeon.
Other factors, like a surgeon's patient volume, also influenced the likelihood of ordering genetic testing, with low- and medium-volume surgeons being less likely to order it than high-volume ones.
A sizable minority of surgeons, the researchers found, order genetic testing without referring patients to genetic counseling. Additionally, many surgeons said they never or rarely delay surgery to wait for testing results, though the researchers noted that they don't know if that is due to surgeons' attitudes, patient choice, or clinical circumstances.
Also, patients with no or with public insurance and African-American patients were less likely to get genetic testing, which the researchers said indicates that there are still disparities in and access barriers to testing.
Their findings, they said, highlight the variability in genetic testing and counseling following a breast cancer diagnosis.
"Genetic testing can help inform decisions about breast cancer treatment and prevention of future cancers in patients and in their families. It's important to ensure patients who need this information receive it as part of the treatment discussion, regardless of the surgeon they see," Katz said.