Current National Comprehensive Cancer Network (NCCN) criteria may prevent genetic testing in “a substantial proportion” of women who carry germline pathogenic variants in breast cancer predisposition genes, according to investigators.
They found that, by expanding NCCN criteria to include germline genetic testing for all women diagnosed with breast cancer at age 65 or younger, the sensitivity of testing for nine well-established breast cancer predisposition genes would improve from 70% to more than 90%. The sensitivity for detection of BRCA1 and BRCA2 only would improve from 87% to greater than 98%.
, of the Mayo Clinic, Rochester, Minn., and colleagues reported these findings in the .
“In a large unselected series of women with breast cancer, we demonstrate that expanding the NCCN testing criteria to include all women diagnosed with breast cancer at or before the age of 65 years has the potential to improve the sensitivity of germline genetic testing without the need for evaluation of all women with breast cancer,” Dr. Yadav and colleagues wrote.
, who was vice-chair of the panel that drew up the NCCN guidelines, said in an interview that the guideline authors tried to achieve a balance.
“We’ve known that NCCN misses cases and indications, but it comes down to whether the goal is to test all women with mutations or to have criteria that are a cost-effective and reasonable compromise to capture as many patients as possible,” said Mr. Pilarski, a licensed genetic counselor at the Ohio State University Wexner Medical Center in Columbus.
Current NCCNfor genetic/familial high-risk assessment for breast, ovarian, and pancreatic cancer recommend testing for individuals with blood relatives who have known or likely pathogenic variants, as well as patients with breast cancer diagnosed at age 45 or younger, patients aged 46-50 years with unknown or limited family history, patients with a second breast cancer diagnosed at any age, patients with triple-negative breast cancer diagnosed at age 60 or younger, and patients with breast cancer diagnosed at any age if they are of Ashkenazi Jewish ancestry.
But as Dr. Yadav and colleagues note, two recent studies (; ) suggested that up to 50% of germline pathogenic variants could be missed if testing were based solely on NCCN criteria.
Based on these findings, the American Society of Breast Surgeons issued a consensus guideline on genetic testing for hereditary breast cancer (), which states that, “genetic testing should be made available to all patients with a personal history of breast cancer.”
“Without question, if your goal is to identify everyone with a mutation, you’d have to test every cancer patient,” Mr. Pilarski said. “At this point, the ASBrS [American Society of Breast Surgeons] are the only group that have proposed that, and a lot of us feel that’s going too far at this point in time, and so the issue becomes what’s reasonable before that, and I think this paper is a great step forward.”
Cutting through the confusion
To see whether tweaking the existing guidelines could help clarify the issues surrounding genetic testing for breast cancer, Dr. Yadav and colleagues looked at a cohort of patients from the Mayo Clinic Breast Cancer Study. This prospective registry was open to all women evaluated at the Mayo Clinic Rochester for a first diagnosis of invasive breast cancer or ductal carcinoma in situ from May 2000 through May 2016.
The women were evaluated for germline pathogenic variants in nine breast cancer predisposition genes: ATM, BRCA1, BRCA2, CDH1, CHEK2, NF1, PALB2, PTEN, and TP53.
The researchers found that, of the 3,907 women in the sample, 1,872 (47.9%) would have been recommended for testing under the NCCN criteria, but the remaining 2,035 would not.
Women who met NCCN criteria were significantly more likely to carry a pathogenic variant (9% vs. 3.5%, P less than .001). However, 29.9% of women with pathogenic variants in the nine-gene panel and 13.1% of those with pathogenic variants in BRCA1 or BRCA2 did not qualify for testing by NCCN criteria.
The sensitivity of NCCN criteria was 70% for the nine-gene panel and 87% for BRCA 1 and BRCA 2, with a 53% specificity.
But if the criteria were expanded to include all women age 65 years and younger with a breast cancer diagnosis, the sensitivity for the nine-gene panel would increase to 92.1%, and the sensitivity for BRCA1 and BRCA2 only would climb to greater than 98.1%, with a specificity of approximately 22% for each test combination.
The authors acknowledged that they did not assess the cost-effectiveness of the testing criteria.
This study was supported by grants from the National Institutes of Health and the Breast Cancer Research Foundation. Authors disclosed relationships with Grail, bioTheranostics, Myriad Genetics, and other companies. Mr. Pilarski reported no conflicts of interest.
SOURCE: Yadav S et al. J Clin Oncol. 2020 Mar 3.