To assess multi-gene panel testing in an ethnically diverse clinical cancer genetics practice. We conducted a retrospective study of individuals with a personal or family history of cancer undergoing clinically indicated multi-gene panel tests of 6–110 genes, from six commercial laboratories. The 475 patients in the study included 228 Hispanics (47.6%), 166 non-Hispanic Whites (35.4%), 55 Asians (11.6%), 19 Blacks (4.0%), and seven others (1.5%). Panel testing found that 15.6% (74/475) of patients carried deleterious mutations for a total of 79 mutations identified. This included 7.4% (35/475) of patients who had a mutation identified that would not have been tested with a gene-by-gene approach. The identification of a panel-added mutation impacted clinical management for most of cases (69%, 24/35), and genetic testing was recommended for the first degree relatives of nearly all of them (91%, 32/35). Variants of uncertain significance (VUSs) were identified in a higher proportion of tests performed in ethnic minorities. Multi-gene panel testing increases the yield of mutations detected and adds to the capability of providing individualized cancer risk assessment. VUSs represent an interpretive challenge due to less data available outside of White, non-Hispanic populations. Further studies are necessary to expand understanding of the implementation and utilization of panels across broad clinical settings and patient populations.

Purpose Multiplex gene panel testing (MGPT) allows for the simultaneous analysis of germline cancer susceptibility genes. This study describes the diagnostic yield and patient experiences of MGPT in diverse populations. Patients and Methods This multicenter, prospective cohort study enrolled participants from three cancer genetics clinics—University of Southern California Norris Comprehensive Cancer Center, Los Angeles County and University of Southern California Medical Center, and Stanford Cancer Institute—who met testing guidelines or had a 2.5% or greater probability of a pathogenic variant (N = 2,000). All patients underwent 25- or 28-gene MGPT and results were compared with differential genetic diagnoses generated by pretest expert clinical assessment. Post-test surveys on distress, uncertainty, and positive experiences were administered at 3 months (69% response rate) and 1 year (57% response rate). Results Of 2,000 participants, 81% were female, 41% were Hispanic, 26% were Spanish speaking only, and 30% completed high school or less education. A total of 242 participants (12%) carried one or more pathogenic variant (positive), 689 (34%) carried one or more variant of uncertain significance (VUS), and 1,069 (53%) carried no pathogenic variants or VUS (negative). More than one third of pathogenic variants (34%) were not included in the differential diagnosis. After testing, few patients (4%) had prophylactic surgery, most (92%) never regretted testing, and most (80%) wanted to know all results, even those of uncertain significance. Positive patients were twice as likely as negative/VUS patients (83% v 41%; P < .001) to encourage their relatives to be tested. Conclusion In a racially/ethnically and socioeconomically diverse cohort, MGPT increased diagnostic yield. More than one third of identified pathogenic variants were not clinically anticipated. Patient regret and prophylactic surgery use were low, and patients appropriately encouraged relatives to be tested for clinically relevant results.

Purpose Mutations in the CDH1 gene confer up to an 80% lifetime risk of diffuse gastric cancer and up to a 60% lifetime risk of lobular breast cancer. Testing for CDH1 mutations is recommended for individuals who meet the International Gastric Cancer Linkage Consortium (IGCLC) guidelines. However, the interpretation of unexpected CDH1 mutations identified in patients who do not meet IGCLC criteria or do not have phenotypes suggestive of hereditary diffuse gastric cancer is clinically challenging. This study aims to describe phenotypes of CDH1 mutation carriers identified through multigene panel testing (MGPT) and to offer informed recommendations for medical management. Patients and Methods This cross-sectional prevalence study included all patients who underwent MGPT between March 2012 and September 2014 from a commercial laboratory (n = 26,936) and an academic medical center cancer genetics clinic (n = 318) to estimate CDH1 mutation prevalence and associated clinical phenotypes. CDH1 mutation carriers were classified as IGCLC positive (met criteria), IGCLC partial phenotype, and IGCLC negative. Results In the laboratory cohort, 16 (0.06%) of 26,936 patients were identified as having a pathogenic CDH1 mutation. In the clinic cohort, four (1.26%) of 318 had a pathogenic CDH1 mutation. Overall, 65% of mutation carriers did not meet the revised testing criteria published in 2015. All three CDH1 mutation carriers who had risk-reducing gastrectomy had pathologic evidence of diffuse gastric cancer despite not having met IGCLC criteria. Conclusion The majority of CDH1 mutations identified on MGPT are unexpected and found in individuals who do not fit the accepted diagnostic testing criteria. These test results alter the medical management of CDH1-positive patients and families and provide opportunities for early detection and risk reduction.

Research on the communication of genetic test results has focused predominately on non-Hispanic White (NHW) mutation-positive families with high-risk hereditary cancer conditions. Little is known about this process for racially and ethnically diverse individuals or for those with mutations in moderate risk genes. The communication behaviors of study participants who carry a gene mutation were analyzed 3 months after disclosure of genetic test results. Participants were queried about communication of their results, as part of a prospective study of multi-gene panel genetic testing. The responses of particpants who tested positive were analyzed by race/ethnicity and by level of cancer risk (high vs. moderate). Of the 216 mutation-positive study participants, 136 (63%) responded. Self-reported race/ethnicity was 46% NHW, 41% Hispanic, 10% Asian, and 2% Black. The majority (99.0%, n = 135) had shared their results with someone and 96% had told a family member (n = 130). Hispanic respondents were less likely to have told a healthcare provider about their results than NHW (29% vs. 68%, p < .0001). Asian respondents were less likely than NHW to encourage family members to undergo testing (OR = 0.1, p = .03); but Asian family members were more likely to undergo testing (OR = 8.0, p = .03). There were no differences in communication between those with a mutation in a high- or moderate-risk gene. Three months post genetic testing, communication of results was very high; 30% reported a family member underwent genetic testing. Further studies are needed to better understand the communication process in individuals from diverse racial/ethnic backgrounds.

BACKGROUND:Little is known about the psychological outcomes of germline multigene panel testing, particularly among diverse patients and those with moderate-risk pathogenic variants (PVs). METHODS: Study participants (N = 1264) were counseled and tested with a 25-or 28-gene panel and completed a 3-month postresult survey including the Multidimensional Impact of Cancer Risk Assessment (MICRA). RESULTS: The mean age was 52 years, 80% were female, and 70% had cancer; 45% were non-Hispanic White, 37% were Hispanic, 10% were Asian, 3% were Black, and 5% had another race/ethnicity. Approximately 28% had a high school education or less, and 23% were non-English-speaking. The genetic test results were as follows: 7% had a high-risk PV, 6% had a moderate-risk PV, 35% had a variant of uncertain significance (VUS), and 52% were negative. Most participants (92%) had a total MICRA score ≤ 38, which corresponded to a mean response of "never," "rarely," or only "sometimes" reacting negatively to results. A multivariate analysis found that mean total MICRA scores were significantly higher (more uncertainty/distress) among high-and moderate-risk PV carriers (29.7 and 24.8, respectively) than those with a VUS or negative results (17.4 and 16.1, respectively). Having cancer or less education was associated with a significantly higher total MICRA score; race/ethnicity was not associated with the total MICRA score. High-and moderate-risk PV carriers did not differ significantly from one another in the total MICRA score, uncertainty, distress, or positive experiences. CONCLUSIONS: In a diverse population undergoing genetic counseling and multigene panel testing for hereditary cancer risk, the psychological response corresponded to test results and showed low distress and uncertainty. Further studies are needed to assess patient understanding and subsequent cancer screening among patients from diverse backgrounds.