Huge Underuse of Germline Testing for Cancer Patients

CHICAGO — Fewer than 7% of patients newly diagnosed with cancer are tested for germline genetic mutations, and the percentage tested was even lower among racial and ethnic minorities, a huge study has found.

Information from germline genetic testing could affect a patient’s cancer care. For example, such testing could indicate that targeted therapies would be beneficial, and it would have implications for close relatives who may carry the same genes.

The finding that so few patients with newly diagnosed cancer were tested comes from an analysis of data on more than 1.3 million individuals across two US states. The data were taken from the Surveillance, Epidemiology, and End Results (SEER) registry.

The rate is “well below guideline recommendations,” said study presenter Alison Kurian, MD, Department of Medicine, Stanford University School of Medicine, Stanford, California.

“Innovative care delivery” is needed to tackle the problem, including the streamlining of pretest counseling, making posttest counseling more widely available, and employing long-term follow-up to track patient outcomes, she suggested.

“I do think this is a time for creative solutions of a number of different kinds,” she said. She suggested that lessons could be learned from the use of telemedicine during the COVID-19 pandemic. She also noted that “there have been some interesting studies on embedding genetic counselors in oncology clinics.”

Kurain presented the study here at the American Society of Clinical Oncology (ASCO) 2023 annual meeting on June 5. The study was simultaneously published in the Journal of the American Medical Association.

The current results represent a “missed opportunity for decrease the population-level burden of cancer,” say experts writing in an accompanying editorial.

“Clinicians should recommend testing to their patients and provide them with the information necessary to make informed decisions about whether to undergo testing,” Zsofia K. Stadler, MD, and Deborah Schrag, MD, MPH, from Memorial Sloan Kettering Cancer Center, New York City, write in their editorial.

They also suggest novel approaches to widen access, such as use of point-of-care testing, tele-counseling, and, in the future, chatbots to respond to patient questions.

“With greater emphasis on overcoming both health system and patient-level barriers to genetic cancer susceptibility testing for patients with cancer, treatment outcomes will improve and cancer diagnoses and related deaths in family members will be prevented,” they conclude.

At the meeting, invited discussant Erin Frances Cobain, MD, assistant professor of medical oncology, University of Michigan Health, Ann Arbor, Michigan, referring to breast cancer as an example, said that progress has “stagnated” in recent years.

The study found a higher rate of gene testing among patients with newly diagnosed breast cancer, at just over 20%.

Cobain argued that this was still too low. She pointed out that “a recent study suggested that over 60% of individuals with an incident cancer diagnosis would meet criteria for genetic testing by National Comprehensive Cancer Network guidelines.

“This may be because testing is not offered, there may be poor access to genetic counseling resources, or patients may be offered testing but decline it,” she suggested.

One compelling reason to conduct genetic testing for patients newly diagnosed with breast cancer is that it may show that they are candidates for treatment with PARP (poly[ADP]-ribose polymerase) inhibitors, which “may have a direct impact on cancer-related mortality,” she pointed out.

“We need increased awareness and access to genetic testing resources for patients with breast cancer, particularly for racial and ethnic minorities,” she said.

Cobain also noted that finding variants of uncertain significance (VUS) was more likely among patients from racial and ethnic minorities than among White patients. She said such a finding “increases patient and physician anxiety,” and there may be “unclear optimal management recommendations for these patients.”

Details of the Study

Germline genetic testing is “increasingly essential for cancer care,” Kurain told the meeting.

It is central to risk-adapted screening and secondary prevention, the use of targeted therapies, including PARP and checkpoint inhibitors, and cascade testing to identify at-risk relatives.

She pointed out that in clinical practice, testing has “evolved rapidly.” Panels include more and more genes. In addition, the cost of these tests is falling, and guidelines have become “more expansive.”

However, “little is known about genetic testing use and results,” Kurian noted.

The team therefore undertook the SEER-GeneLINK initiative, which involved patients aged ≥20 years who were diagnosed with cancer between January 1, 2013, and March 31, 2019, and who were reported to statewide SEER registries in California and Georgia.

The team looked for patients for whom germline genetic test results had been reported by the four laboratories that performed the majority of patient testing in the two states. Results were categorized as pathogenic, benign, or VUS.

The results were classified on the basis of current guidelines for testing and/or management as related to breast/ovarian cancer, gastrointestinal cancer, other hereditary cancers, or those with no guidelines for testing or management.

Kurian reported that from an overall population of 1,412,388 patients diagnosed with cancer, 1,369,660 were eligible for inclusion. Of those, about half (51.9%) were women, and the majority (86.3%) were aged 50 years or older.

Many of these patients (61.4%) were non-Hispanic White persons, and slightly fewer than half (49.8%) were deemed to be in medium or high poverty, as determined using US Census tract levels.

Overall, germline genetic testing was performed in 93,052 (6.8%) of patients over the study period.

Women were more likely to have undergone germline mutation testing than men, at 13.9% vs 2.2%, as were patients aged 20–49 years, at 22.1% vs 8.2% for those aged 50–69 years, and 3.3% for those aged 70 years and older.

The number of genes for which testing was conducted increased from a median of two in 2013 to 34 in 2019. Rates of VUS increased more than that for pathologic variants and substantially more so in non-White patients.

By 2019, the ratio of VUS to pathologic variants stood at 1.7 among White patients, vs 3.9 among Asian patients, 3.6 among Black patients, and 2.2 among Hispanic patients.

The majority of identified pathologic variants that were related to the diagnosed cancer and genes with testing and/or management guidelines accounted for 67.5% to 94.9% of such variants.

Regarding specific cancer diagnoses, Kurian said that over the course of the study period, testing rates consistently exceeded 50% only among male breast cancer patients.

There were rapid increases in testing for ovarian cancer, from 28.0% of cases in 2013 to 54.0% in 2019. For pancreatic cancer, rates increased from 1.0% to 19.0% over the same period, and for prostate cancer, rates increased from 0.1% to 4.0%. She suggested that these increases in rates may be related to the approval of PARP inhibitors for use in these indications.

However, there was little change in the rates of germline mutation testing for lung cancer patients, from 01% in 2013 to 0.8% in 2019, and for other cancers, from 0.3% to 2.0%.

The results also revealed racial and ethnic differences in testing after controlling for age, cancer type, and year. Over the course of the study period, 8.0% of White patients underwent genetic testing, compared with 6.0% each for Asian, Black, and Hispanic patients and 5.0% for other patients (P < .001).

With regard specifically to male and female breast cancer and ovarian cancer, testing rates were 31% among White patients, 22% for Asian patients, 25% for Black patients, and 23% for Hispanic patients (P < .001).

Kurian acknowledged that the study is limited by a lack of testing from other laboratories and direct-to-consumer test data, although a recent survey suggested that this represents fewer than 5% of all germline genetic tests.

She also noted that the SEER registries do not collect data on family history or tumor sequencing.

The study was funded by the National Institutes of Health, and the Centers for Disease Control and Prevention. Kurian has relationships with Adela, Ambry Genetics, Color Genomics, GeneDx/BioReference, Genentech, InVitae, and Myriad Genetics. Other authors report numerous relationships with industry. Cobain has relationships with AstraZeneca, Daiichi Sankyo, Athenex, Ayala Pharmaceuticals, bioTheranostics, and Immunomedics. Schrag has relationships with Merck (Inst), JAMA, AACR (Inst), and Grail (Inst). Stadler has relationships with Adverum Biotechnologies, Genentech, Neurogene, Novartis, Optos Plc, Outlook Therapeutics, and Regeneron Pharmaceuticals.

American Society of Clinical Oncology (ASCO) 2023: Abstract 10500. Presented June 5, 2023.

JAMA Oncol. Published online June 5, 2023. Full text, Editorial

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