National Distribution of Cancer Genetic Testing in the United States: Evidence for a Gender Disparity in Hereditary Breast and Ovarian Cancer

Up to 10% of cancers are attributable to inherited gene mutations, such as BRCA1/2 and those associated with Lynch syndrome.¹ Identifying mutation carriers is critical for treatment decisions, cancer prevention, and early detection.² Despite the importance of equal access to testing, there is some evidence for disparities by education level, insurance status, and race/ethnicity.³ Although carrier rates are equivalent between men and women, there may also be a gender disparity in testing.⁴ To date, however, epidemiological studies have largely focused on genetic testing in women and hereditary breast and ovarian cancer (HBOC).⁵ This study describes the US national distribution of genetic testing for hereditary cancer risk, identifies disparities, and assesses whether a gender gap in testing exists.

The data source is the 2015 US National Health Interview Survey (NHIS), a cross-sectional in-person interview gathering self-reported health data for the US population. The study did not meet regulatory definition of a “human subject” study because the data are publically available. Therefore, neither certification of exemption from University of California Los Angeles institutional review board approval was not required.

The outcome of interest was receipt of genetic testing for cancer risk. Affirmative responders were asked 4 subsequent questions that were not mutually exclusive—if their test was for breast cancer, ovarian cancer, colon or rectal cancer, or other cancer. Answers did not have to be concordant with personal and family history.

Sociodemographic factors of individuals obtaining genetic testing were compared with the national sample, including gender, US Census region, race/ethnicity, insurance, citizenship, and education.

To assess the gender disparity in testing, we stratified by type of testing and cancer status. To evaluate potential underrecognition of family medical history leading to lower testing rates, we compared select family medical histories between unaffected men and women.

All estimates were adjusted for complex survey weights and used Taylor series standard errors. Bivariate comparisons were made using adjusted Wald tests and rate ratios (RRs) were generated via Poisson regression.

In the 2015 NHIS, 378 adults (≥18 years) reported a history of genetic testing for cancer, representing 2 498 842 people. Sociodemographic differences in the testing subsample included a lower proportion of Hispanics (10% vs 16%; P = .002), the uninsured (2% vs 10%; P < .001), noncitizens (4% vs 8%; P < .001), and those with less education (high school or General Educational Development (GED) diploma; 30% vs 44%; P < .001). Almost 3 times as many women received testing as men (73% vs 27%; P < .001). This disparity persisted for unaffected men, testing at half the rate of unaffected women (RR, 0.51; 95% CI, 0.36-0.73) (Table 1).

Three-quarters of genetic testing was for breast/ovarian cancer, 24% for colorectal cancer, and 22% for other cancers. Among the unaffected, men underwent testing for breast/ovarian cancer at one-tenth the rate of women (RR, 0.10; 95% CI, 0.05-0.23). There was no gender disparity for colorectal or other cancer testing (Table 2).

There were no differences in reported family history between unaffected men and women (number of first-degree female relatives with breast cancer, breast cancer at ≤50 years, or ovarian cancer).

Cancer genetic testing seems to reach a broad geographic and sociodemographic population in this national survey. However, there remain underrepresented groups, including Hispanics, the uninsured, noncitizens, and those with less education. Most strikingly, unaffected men underwent genetic testing at half the rate of unaffected women, owing to a 10 to 1 disparity in HBOC testing.

Previous theories⁴ for underutilization of HBOC testing in men include (1) lack of patient and clinician awareness on the importance of HBOC mutation status—despite the risks of male breast, pancreatic, melanoma, and aggressive prostate cancers,⁷ and (2) social roles of men vs women in health. The latter argument seems less likely given the lack of gender disparity in colorectal/other cancer testing. Limitations of this study include self-reported data, recall bias, and limited details regarding reason for testing. Large national efforts, including educational campaigns targeting male HBOC testing, must address this disparity to enable uniform opportunities for cancer prevention, early detection, and treatment for all at-risk individuals and their family members.

Accepted for Publication: January 26, 2018.

Corresponding Author: Christopher P. Childers, MD, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, 10833 Le Conte Ave, CHS 72-247, Los Angeles, CA 90095 (cchilders@mednet.ucla.edu).

Published Online: April 26, 2018. doi:10.1001/jamaoncol.2018.0340

Author Contributions: Ms K. K. Childers and Dr C. P. Childers had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: K. K. Childers, C. P. Childers.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: K. K. Childers, C. P. Childers.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: C. P. Childers.

Obtained funding: C. P. Childers.

Administrative, technical, or material support: Maggard-Gibbons.

Study supervision: Maggard-Gibbons, Macinko.

Conflict of Interest Disclosures: None reported.

Funding/Support: Dr C. P. Childers receives funding from Agency for Healthcare Research and Quality grant No. F32HS025079.

Role of the Funder/Sponsor: The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.