April 09, 2019
3 min read
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Genetic testing rates low among women with ovarian, breast cancer

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Allison W. Kurian, MD, MSc
Allision W. Kurian

Less than one-third of women diagnosed with ovarian cancer in two large, diverse states between 2013 and 2014 received subsequent genetic testing, according to results of a study published in Journal of Clinical Oncology.

The rate among women with breast cancer was even lower, with approximately one-quarter of those diagnosed in California and Georgia during the 2-year period undergoing genetic testing for pathogenic variants. Researchers observed notable differences in genetic testing rates when broken down by economic status and race/ethnicity.

“A 30% genetic testing rate for patients with ovarian cancer is inadequate, because guidelines have recommended testing all patients with high-grade, serous ovarian cancer for a decade,” Allision W. Kurian, MD, MSc, associate professor of medicine and of health and research policy at Stanford University School of Medicine, and colleagues wrote.

Results showed pathogenic variants in 14.5% of women with ovarian cancer and 7.8% of women with breast cancer when tested for all genes that current guidelines recommend for their cancer type. These are “cancer-associated mutations that could be used to drive care decisions and influence family members’ health care and screening choices,” Kurian said in a press release.

“Almost nothing is known about the prevalence of pathogenic variants on multiple-gene panels among clinically tested, population-based patients with breast cancer and patients with ovarian cancer,” Kurian and colleagues wrote. “Yet, such knowledge is essential to inform population-wide health policy, resource planning, and development of testing guidelines.”

Kurian added: “We initiated this study ... because we wanted to see what cancer genetic testing and results looked like in the real world.”

The researchers obtained SEER data on women diagnosed with ovarian cancer (n = 6,001) and breast cancer (n = 77,085) in California and Georgia between 2013 and 2014. An independent broker anonymously matched the women with multiple-gene panel germline genetic testing results from four laboratories responsible for most of the genetic testing in the study regions.

Researchers excluded women whose testing was ordered because of a relapsed ovarian or breast cancer diagnosis, as well as women diagnosed before age 20 years or whose race was unknown.

Results showed 30.9% of women with ovarian cancer and 24.1% of women with breast cancer had genetic testing results.

Genetic testing for those with ovarian cancer appeared less common among black women (21.6%; 95% CI, 18.1-25.4) than white women (33.8%; 95% CI, 32.3-35.3). The results for breast cancer showed similar testing rates regardless of race or ethnicity.

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Uninsured women with ovarian cancer had a lower genetic testing rate (20.8%; 95% CI, 15.5-26.9) than insured women (35.3%; 95% CI, 33.8-36.9), whereas results for breast cancer showed a slightly higher rate for uninsured vs. insured women (28.8% vs. 25.8%).

A higher proportion of women with ovarian cancer who underwent genetic testing lived in low-poverty (< 10%) vs. high-poverty ( 20%) areas (37.8% vs. 20.1%).

“The large socioeconomic disparities in test receipt after ovarian cancer diagnosis highlight the challenges of ensuring universal testing access,” Kurian and colleagues wrote.

The researchers said they “observed little racial/ethnic variation in overall pathogenic variant prevalence,” but that there were significant differences for certain variations.

The most common pathogenic variants among women with breast cancer included BRCA1 (3.2%), BRCA2 (3.1%), CHEK2 (1.6%), PALB2 (1%), ATM (0.7%) and NBN (0.4%). Variants among women with ovarian cancer included BRCA1 (8.7%), BRCA2 (5.8%), CHEK2 (1.4%) BRIP1 (0.9%), MSH2 (0.8%) and ATM (0.6%).
BRCA1 appeared more prevalent among Hispanic women with ovarian cancer (16.1%; 95% CI, 11.8-21.2) than among white women (7.2%; 95% CI, 5.9-8.8). CHEK2 appeared more prevalent among white women with breast cancer (2.3%; 95% CI, 1.8-2.8) vs. black women (0.1%; 95% CI, 0-0.8).

The researchers acknowledged that the regional focus on women from Georgia and California may limit the applicability of their results to a larger population. They noted, however, that there was little variation across the variables tested when comparing the two states.

Other study limitations include the brief study period and the exclusion of data from laboratories that offer consumer-direct genetic testing services. Including commercial genetic testing results may have an effect on socioeconomic differences observed in the study, the authors wrote.

“Our expanded population-level focus on more than 83,000 patients with breast cancer or ovarian cancer offers granular detail on testing gaps, disparities and gene-specific results at a major inflection point in the implementation of precision oncology,” Kurian and colleagues wrote. “Many factors conspire to limit genetic testing in those with clinical indications, including patients’ and clinicians’ attitudes about the value of genetic testing and the challenges of integrating genetic testing into the cancer treatment workflow.” – by Drew Amorosi

Disclosure: Kurian reports research funding to her institution from Myriad Genetics. Please see the study for all other authors’ relevant financial disclosures.