Emerging Opportunity of Cascade Genetic Testing for Population-Wide Cancer Prevention and Control

How hereditary cancer risk disclosure to relatives is handled in practice - Patient perspectives from a Swedish cancer genetics clinic

OBJECTIVES

Hereditary cancer risks can be effectively managed if at-risk relatives enroll in surveillance and preventive care. Family-mediated risk disclosure has internationally been shown to be incomplete, selective and leave over a third of eligible at-risk individuals without access to genetic counseling. We explored patients handling of cancer risk information in practice.

METHODS

We conducted twelve semi-structured interviews with patients who had completed their genetic counseling and been asked to disclose risk information to relatives. Questions were designed to investigate lived experiences of communicating hereditary risk and focused on disclosure strategies, intrafamilial interactions and emotional responses.

RESULTS

Qualitative content analysis yielded five categories. These span personal fears, shared responsibilities, feeling of empowerment, innovative solutions and unmet needs. Patients put high value on collaboration with their genetic healthcare professionals but also solicited better overview of the counseling process and more personalized, case-tailored information.

CONCLUSIONS

Our results add novel insights about the practical strategies employed by genetic counselees and their motivations behind disclosing hereditary risk information to relatives.

PRACTICE IMPLICATIONS

A patient-centered cancer genetics care would clarify roles and responsibilities around risk disclosure, inform counselees about the process upfront and tailor information to offer case-specific data with the family's inheritance pattern explained.

Cascade testing in Italian Hereditary Breast Ovarian Cancer families: a missed opportunity for cancer prevention?

Healthy carriers of BRCA1/2 pathogenic variants (PVs) may benefit from risk-reducing measures of proven efficacy. The main approach to identify these individuals is cascade testing, and strategies to support this complex process are under investigation. In Italy, cascade testing has received little attention; therefore, we analyzed the uptake and characteristics of BRCA1/2 cascade testing in families diagnosed with HBOC between 2017 and 2019 at two Italian genetics centers. All blood relatives aged 18 years or older at September 2022 and who could be involved in the first step of cascade testing (i.e., all the living relatives closest to the proband) were included. In addition to first-degree relatives, individuals who were second-, third- or fourth-degree relatives were included if the closest relative(s) was/were deceased. Overall, 213 families were included (103, Genoa; 110, Bologna). Most probands were women affected by breast and/or ovarian cancer (86.4%, Genoa; 84.5%, Bologna), and the branch segregating the PV was known/suspected in 62% of families (62.1%, Genoa; 60.9%, Bologna). Overall, the uptake of cascade testing was 22.8% (25.8%, Genoa; 19.9%, Bologna; OR = 0.59: 95%CI 0.43-0.82). It was strongly associated with female gender (OR = 3.31, 95%CI 2.38-4.59), age ≤ 70 years (< 30 years OR = 3.48, 95%CI 1.85-6.56; 30-70 years OR = 3.08, 95%CI 2.01-4.71), first-degree relationship with the proband (OR = 16.61, 95%CI 10.50-26.28) and segregation of the PV in both the maternal (OR = 2.54, 95%CI 1.72-3.75) and the paternal branch (OR = 4.62, 95%CI 3.09-6.91). These real-world data may be important to inform the design and implementation of strategies aimed at improving the uptake of HBOC cascade testing in Italy.

Germline Genetic Testing After Cancer Diagnosis

Importance

Germline genetic testing is recommended by practice guidelines for patients diagnosed with cancer to enable genetically targeted treatment and identify relatives who may benefit from personalized cancer screening and prevention.

Objective

To describe the prevalence of germline genetic testing among patients diagnosed with cancer in California and Georgia between 2013 and 2019.

Design, Setting, and Participants

Observational study including patients aged 20 years or older who had been diagnosed with any type of cancer between January 1, 2013, and March 31, 2019, that was reported to statewide Surveillance, Epidemiology, and End Results registries in California and Georgia. These patients were linked to genetic testing results from 4 laboratories that performed most germline testing for California and Georgia.

Main Outcomes and Measures

The primary outcome was germline genetic testing within 2 years of a cancer diagnosis. Testing trends were analyzed with logistic regression modeling. The results of sequencing each gene, including variants associated with increased cancer risk (pathogenic results) and variants whose cancer risk association was unknown (uncertain results), were evaluated. The genes were categorized according to their primary cancer association, including breast or ovarian, gastrointestinal, and other, and whether practice guidelines recommended germline testing.

Results

Among 1 369 602 patients diagnosed with cancer between 2013 and 2019 in California and Georgia, 93 052 (6.8%) underwent germline testing through March 31, 2021. The proportion of patients tested varied by cancer type: male breast (50%), ovarian (38.6%), female breast (26%), multiple (7.5%), endometrial (6.4%), pancreatic (5.6%), colorectal (5.6%), prostate (1.1%), and lung (0.3%). In a logistic regression model, compared with the 31% (95% CI, 30%-31%) of non-Hispanic White patients with male breast cancer, female breast cancer, or ovarian cancer who underwent testing, patients of other races and ethnicities underwent testing less often: 22% (95% CI, 21%-22%) of Asian patients, 25% (95% CI, 24%-25%) of Black patients, and 23% (95% CI, 23%-23%) of Hispanic patients (P < .001 using the χ2 test). Of all pathogenic results, 67.5% to 94.9% of variants were identified in genes for which practice guidelines recommend testing and 68.3% to 83.8% of variants were identified in genes associated with the diagnosed cancer type.

Conclusions and Relevance

Among patients diagnosed with cancer in California and Georgia between 2013 and 2019, only 6.8% underwent germline genetic testing. Compared with non-Hispanic White patients, rates of testing were lower among Asian, Black, and Hispanic patients.

Improving genetic testing following abnormal mismatch repair immunohistochemistry results in endometrial cancer

OBJECTIVES

Although universal mismatch repair (MMR) immunohistochemistry (IHC) in endometrial cancer began at our institution in July 2015, not all eligible patients were referred for genetic testing (GT). In April 2017, genetic counselors obtained IHC data and contacted physicians to approve genetic counseling referrals (GCRs) for Lynch Syndrome (LS) in eligible patients. We assessed if this protocol increased frequency of GCRs and GT in patients with abnormal MMR IHC.

METHODS

We retrospectively (7/2015-5/2022) identified patients with abnormal MMR IHC at a large urban hospital. GCRs and GT were compared between cases from 7/2015-4/2017 (pre-protocol) and 5/2017-5/2022 (post-protocol) with chi-square and Fisher's exact tests.

RESULTS

Of 794 patients with IHC testing, 177 (22.3%) had abnormal MMR results with 46 (26.0%) meeting criteria for LS screening with GT. Of 46 patients, 16 (34.8%) were identified prior to and 30 (65.2%) after the protocol initiation. GCRs significantly increased from 11/16 (68.8%) to 29/30 (96.7%) in the pre-protocol versus post-protocol groups, p = 0.02. There was no statistically significant difference in GT between groups (10/16, 62.5% vs 26/30, 86.7%, p = 0.07). Of 36 patients who underwent GT, 16 (44.4%) had LS: MSH6, 9; MSH2, 4; PMS2, 2; MLH1, 1.

CONCLUSIONS

Increased frequency of GCRs was observed following the change in protocol, which is important as LS screening has clinical implications for patients and their families. Despite this additional effort, approximately 15% who met criteria did not undergo GT; further efforts such as universal germline testing in patients with endometrial cancer should be considered.

Cascade Genetic Risk Education and Testing in Families With Hereditary Cancer Syndromes: A Pilot Study

PURPOSE

Cascade genetic risk evaluation in families with hereditary cancer can reduce the burden of disease but the rate of germline genetic testing in relatives of patients at risk is low.

METHODS

We identified all 277 women diagnosed with breast cancer in Georgia in 2017 who linked to a clinically actionable germline pathogenic variant through a Surveillance, Epidemiology, and End Results registry-variant linkage initiative. We surveyed them, and then invited eligible respondents to an online platform hosted by a navigator that offered cancer genetic risk education and germline genetic testing to untested relatives. We randomly assigned patient-family clusters at the time of the patient enrollment offer to free versus $50 (USD) test cost. Patients invited relatives to join the study through personalized e-mail. Enrolled relatives received online cancer genetic education and the opportunity to order clinical germline genetic testing through the platform. The primary outcome was the number of relatives who ordered genetic testing.

RESULTS

One hundred twenty-five of 277 patients completed surveys (45.2%). Most respondents were eligible for the trial offer (113 of 125; 90.4%). In the free testing arm, 20 of 56 eligible patients participated (35.7% of eligible respondents) and they invited 28 relatives: 12 relatives enrolled and 10 ordered testing. In the $50 (USD) arm, 16 of 57 eligible patients participated (28.1%) and they invited 38 relatives: 18 relatives enrolled and 17 ordered testing.

CONCLUSION

Cascade genetic testing in families with hereditary cancer syndromes accrued through a population-based cancer registry can be achieved through an online platform that offers genetic risk education and low-cost testing to relatives. A modest charge did not appear to influence the percentage of participating patients, numbers of participating relatives, and numbers of relatives who received genetic testing.

Germline Pathogenic Variant Prevalence Among Latin American and US Hispanic Individuals Undergoing Testing for Hereditary Breast and Ovarian Cancer: A Cross-Sectional Study

PURPOSE

To report on pathogenic germline variants detected among individuals undergoing genetic testing for hereditary breast and/or ovarian cancer (HBOC) from Latin America and compare them with self-reported Hispanic individuals from the United States.

METHODS

In this cross-sectional study, unrelated individuals with a personal/family history suggestive of HBOC who received clinician-ordered germline multigene sequencing were grouped according to the location of the ordering physician: group A, Mexico, Central America, and the Caribbean; group B, South America; and group C, United States with individuals who self-reported Hispanic ethnicity. Relatives who underwent cascade testing were analyzed separately.

RESULTS

Among 24,075 unrelated probands across all regions, most were female (94.9%) and reported a personal history suggestive of HBOC (range, 65.0%-80.6%); the mean age at testing was 49.1 ± 13.1 years. The average number of genes analyzed per patient was highest in group A (A 63 ± 28, B 56 ± 29, and C 40 ± 28). Between 9.1% and 18.7% of patients had pathogenic germline variants in HBOC genes (highest yield in group A), with the majority associated with high HBOC risk. Compared with US Hispanics individuals the overall yield was significantly higher in both Latin American regions (A v C P = 1.64×10-9, B v C P < 2.2×10-16). Rates of variants of uncertain significance were similar across all three regions (33.7%-42.6%). Cascade testing uptake was low in all regions (A 6.6%, B 4.5%, and C 1.9%).

CONCLUSION

This study highlights the importance of multigene panel testing in Latin American individuals with newly diagnosed or history of HBOC, who can benefit from medical management changes including targeted therapies, eligibility to clinical trials, risk-reducing surgeries, surveillance and prevention of secondary malignancy, and genetic counseling and subsequent cascade testing of at-risk relatives.

The Impact of Proband Indication for Genetic Testing on the Uptake of Cascade Testing Among Relatives

Although multiple factors can influence the uptake of cascade genetic testing, the impact of proband indication has not been studied. We performed a retrospective, cross-sectional study comparing cascade genetic testing rates among relatives of probands who received either diagnostic germline testing or non-indication-based proactive screening via next-generation sequencing (NGS)-based multigene panels for hereditary cancer syndromes (HCS) and/or familial hypercholesterolemia (FH). The proportion of probands with a medically actionable (positive) finding were calculated based on genes associated with Centers for Disease Control and Prevention (CDC) Tier 1 conditions, HCS genes, and FH genes. Among probands with a positive finding, cascade testing rates and influencing factors were assessed. A total of 270,715 probands were eligible for inclusion in the study (diagnostic n = 254,281,93.9%; proactive n = 16,434, 6.1%). A positive result in a gene associated with a CDC Tier 1 condition was identified in 10,520 diagnostic probands (4.1%) and 337 proactive probands (2.1%), leading to cascade testing among families of 3,305 diagnostic probands (31.4%) and 36 proactive probands (10.7%) (p < 0.0001). A positive result in an HCS gene was returned to 23,272 diagnostic probands (9.4%) and 970 proactive probands (6.1%), leading to cascade testing among families of 6,611 diagnostic probands (28.4%) and 89 proactive probands (9.2%) (p < 0.0001). Cascade testing due to a positive result in an HCS gene was more commonly pursued when the diagnostic proband was White, had a finding in a gene associated with a CDC Tier 1 condition, or had a personal history of cancer, or when the proactive proband was female. A positive result in an FH gene was returned to 1,647 diagnostic probands (25.3%) and 67 proactive probands (0.62%), leading to cascade testing among families of 360 diagnostic probands (21.9%) and 4 proactive probands (6.0%) (p < 0.01). Consistently higher rates of cascade testing among families of diagnostic probands may be due to a perceived urgency because of personal or family history of disease. Due to the proven clinical benefit of cascade testing, further research on obstacles to systematic implementation and uptake of testing for relatives of any proband with a medically actionable variant is warranted.

Challenges for precision public health communication in the era of genomic medicine

Although still in the early stages of development, the advent of fast, high-output, and cost-effective next-generation DNA sequencing technology is moving precision medicine into public health. Before this shift toward next-generation sequencing in public health settings, individual patients met geneticists after showing symptoms and through limited family screening. In the new era of precision public health, everyone is a possible participant in genetic sequencing, simply by being born (newborn screening), by donating blood (biobanking), or through population screening. These initiatives are increasingly offered to individuals throughout their life and more individuals are encountering opportunities to use DNA sequencing. This article raises awareness of these growing areas and calls for different models of public engagement and communication about genomics, including screening asymptomatic populations, obtaining consent for unspecified and unforeseen future uses of genomic data, and managing variants of uncertain significance. Given that such communication challenges loom large, established norms of practice in genomic medicine and research should be reconsidered.

Attitudes and interest in incorporating BRCA1/2 cancer susceptibility testing into reproductive carrier screening for Ashkenazi Jewish men and women

Pathogenic variants in the BRCA1 and BRCA2 (BRCA1/2) genes are associated with elevated cancer risks in men and women. Due to a founder effect, Ashkenazi Jewish individuals are at higher risk for carrying three specific BRCA1/2 pathogenic variants. There have been recent calls for population screening in this population because many carriers do not have family histories suggestive of hereditary cancer. One approach could be to integrate optional BRCA1/2 testing into routinely offered reproductive carrier screening for recessive and X-linked disorders. However, the differing goals of these types of testing (i.e., personal health risks versus family planning) raise questions about the implications for patient education and informed consent. To this end, we aimed to determine interest, attitudes, and preferences regarding integrating such testing by electronically surveying 331 Ashkenazi Jewish participants in JScreen - a national, not-for-profit, at-home carrier screening program focused on genetic risks in Jewish communities. We found that while 41% of participants had plans to pursue BRCA1/2 testing, 93% would have opted for such testing if offered as an add-on to reproductive carrier screening. This was particularly true of those with higher perceived cancer risk and more positive attitudes toward genetic testing. With respect to preferences about delivery of this service, more than 85% of participants preferred remote (telephone, print, or web-based) genetic education rather than traditional genetic counseling. These results suggest that offering optional BRCA1/2 testing within the context of reproductive carrier screening might provide opportunities for cancer prevention without overburdening scarce genetic counseling resources.

Accounting for Intergenerational Cascade Testing in Economic Evaluations of Clinical Genomics: A Scoping Review

OBJECTIVES

Clinical genomics is emerging as a diagnostic tool in the identification of blood relatives at risk of developing heritable diseases. Our objective was to identify how genetic cascade screening has been incorporated into health economic evaluations.

METHODS

A scoping review was conducted to identify how multiple generations of a family were included in economic evaluations of clinical genomic sequencing, how many and which relatives were included, and uptake rates. Databases were searched for full economic evaluations of genetic interventions that screened multiple generations of families and were in English language, and no restrictions were made for disease or publication type. Data were synthesized using a narrative approach.

RESULTS

Twenty-five studies were included covering a range of diseases in various countries. Markov cohort models were mostly used with hypothetical populations and unsupported by clinical evidence. Cascade testing was either the primary intervention or secondary to the index cases. The number and type of relatives were based on assumptions or identified through population or family records, clinical registry data, or clinical literature. Studies included only immediate family members and the uptake of testing ranged between 20% and 100%. All interventions were reported as cost-effective, and a higher number of relatives was a key driver.

CONCLUSIONS

Several economic evaluations have considered the impacts of cascade testing interventions within clinical genomics. Ideally, models supported with high-quality clinical data are needed and, in their absence, transparent and justifiable assumptions of uptake rates and choices about including relatives. Consideration of more appropriate modeling types is required.

A Focus Group Study of Perceptions of Genetic Risk Disclosure in Members of the Public in Sweden: "I'll Phone the Five Closest Ones, but What Happens to the Other Ten?"

This study explores perceptions and preferences on receiving genetic risk information about hereditary cancer risk in members of the Swedish public. We conducted qualitative content analysis of five focus group discussions with participants (n = 18) aged between 24 and 71 years, recruited from various social contexts. Two prominent phenomena surfaced around the interplay between the three stakeholders involved in risk disclosure: the individual, healthcare, and the relative at risk. First, there is a genuine will to share risk information that can benefit others, even if this is difficult and causes discomfort. Second, when the duty to inform becomes overwhelming, compromises are made, such as limiting one’s own responsibility of disclosure or projecting the main responsibility onto another party. In conclusion, our results reveal a discrepancy between public expectations and the actual services offered by clinical genetics. These expectations paired with desire for a more personalized process and shared decision-making highlight a missing link in today’s risk communication and suggest a need for developed clinical routines with stronger healthcare–patient collaboration. Future research needs to investigate the views of genetic professionals on how to address these expectations to co-create a transparent risk disclosure process which can realize the full potential of personalized prevention.

Profile of Pathogenic Mutations and Evaluation of Germline Genetic Testing Criteria in Consecutive Breast Cancer Patients Treated at a North Indian Tertiary Care Center

Background

The burden of hereditary breast cancer in India is not well defined. Moreover, genetic testing criteria (National Comprehensive Cancer Network [NCCN] and Mainstreaming Cancer Genetics [MCG] Plus) have never been validated in the Indian population.

Methods

All new female breast cancer patients from 1st March 2019 to 28th February 2020 were screened. Those providing informed consent and without previous genetic testing were recruited. Multigene panel testing (107 genes) by next-generation sequencing was performed for all patients. The frequency of pathogenic/likely pathogenic (P/LP) mutations between patients qualifying and not qualifying the testing criteria was compared and their sensitivity was computed.

Results

Overall, 275 breast cancer patients were screened and 236 patients were included (median age 45 years); 30 patients did not consent and 9 patients previously underwent genetic testing. Thirty-four (14%) women had a positive family history and 35% had triple-negative breast cancer. P/LP mutations were found in 44/236 (18.64%) women; mutations in BRCA1 (22/47, 46.8%) and BRCA2 (9/47, 19.1%) were the most common, with 34% of mutations present in non-BRCA genes. Patients qualifying the testing criteria had a higher risk of having a P/LP mutation (NCCN: 23.6% vs. 7.04%, p = 0.03; MCG plus: 24.8% vs. 7.2%, p = 0.01). The sensitivity of the NCCN criteria was 88.6% (75.4–96.2) and 86.36% (72.65–94.83) for MCG plus. More than 95% sensitivity was achieved if all women up to 60 years of age were tested. Cascade testing was performed in 31 previous (16/44 families), with 23 testing positive.

Conclusions

The frequency of P/LP mutations in India is high, with significant contribution of non-BRCA genes. Testing criteria need modification to expand access to testing.

Supplementary Information

The online version contains supplementary material available at 10.1245/s10434-021-10870-w.

Improving our model of cascade testing for hereditary cancer risk by leveraging patient peer support: a concept report

Consensus and evidence suggest that cascade testing is critical to achieve the promise of cancer genetic testing. However, barriers to cascade testing include effective family communication of genetic risk information and family members' ability to cope with genetic risk. These barriers are further complicated by the developmental needs of unaffected family members during critical windows for family communication and adaptation. Peer support could address these barriers. We provide two illustrative examples of ongoing BRCA1/2-related clinical trials that apply a peer support model to improve family communication and functioning. Peer support can augment currently available genetic services to facilitate adjustment to and effective use of cancer genetic risk information. Importantly, this scalable approach can address the presence of cancer risk within families across multiple developmental stages. This applies a family-centered perspective that accommodates all potentially at-risk relatives. This peer support model can be further applied to emerging topics in clinical genetics to expand reach and impact.

Uptake of cancer risk management strategies among women who undergo cascade genetic testing for breast cancer susceptibility genes

BACKGROUND

Uptake of cancer risk management based on inherited predispositions, which encompasses bilateral mastectomy (BLM), bilateral salpingo-oophorectomy (BSO), and intensified screening, is the primary motivation for cascade testing for hereditary breast and ovarian cancer (HBOC). However, long-term outcome data for cascade testers are lacking.

METHODS

Medical records were abstracted for all unaffected women with pathogenic variants in HBOC genes from 2 cancer hospitals (2013-2019) with at least 1 year of follow-up to compare the uptake of surgery and screening between cascade and noncascade testers.

RESULTS

Cascade testers (79.8%) were younger than noncascade testers (mean age, 37.6 vs 43.5 years; P = .002). Among women aged ≥40 years, 43% underwent BLM, and 71.6% underwent BSO, with no significant difference in uptake between cascade and noncascade testers. The mean time to BSO among cascade testers was shorter among women aged ≥40 years versus those aged <40 years (11.8 vs 31.9 months; P = .04); no such difference was observed among noncascade testers. Mammography and breast magnetic resonance imaging rates were low in the recorded 6 years for both groups after genetic counseling.

CONCLUSIONS

Management uptake among cascade testers is high with rates comparable to those for unaffected BRCA-positive women. A large proportion of women act on cascade test results, and this represents a novel report of utilization of cancer management strategies.

Lost opportunities for mismatch repair (MMR) screening among minority women with endometrial cancer

Lynch Syndrome (LS) prevalence in underrepresented minorities are lacking. The objective of this study was to assess the prevalence of LS in a minority patient population. Secondary objectives included identifying factors associated with successful LS screening and to characterize clinicopathologic features. Women with endometrial cancer treated within a university system from 2014 and 2016 were included. Immunohistochemistry (IHC) results of MLH1, PMS2, MSH2 and MSH6 were obtained from medical records and clinicopathologic factors abstracted. Patients not previously screened for LS were screened. 276 patients were evaluable. More minority women were screened as part of their routine cancer care (p = 0.005). Additionally, women 50 years or younger were more likely to be screened for LS compared to women older than 51(p = 0.009) and uninsured or reliant on Medicaid patients (p = 0.011) were more likely to be screened during routine care. Six patients received confirmatory germline testing for LS (4.3%), and another 8 patients had a staining pattern suggestive of LS. In an underrepresented population, the rate of LS in endometrial cancer is similar to previous reports. LS may be under diagnosed and opportunities missed when universal screening is not applied in minority women.

Gene Sequencing for Pathogenic Variants Among Adults With Breast and Ovarian Cancer in the Caribbean

IMPORTANCE

Rates of breast and ovarian cancer are high in the Caribbean; however, to date, few published data quantify the prevalence of inherited cancer in the Caribbean population.

OBJECTIVE

To determine whether deleterious variants in genes that characterize the hereditary breast and ovarian cancer syndrome are associated with the development of breast and ovarian cancer in the English- and Creole-speaking Caribbean populations.

DESIGN, SETTING, AND PARTICIPANTS

This multisite genetic association study used data from germline genetic test results between June 2010 and June 2018 in the Bahamas, Cayman Islands, Barbados, Dominica, Jamaica, Haiti, and Trinidad and Tobago. Next-generation sequencing on a panel of 30 genes and multiplex ligation-dependent probe amplification (BRCA1 and BRCA2) were performed. Medical records were reviewed at time of study enrollment. Women and men diagnosed with breast and ovarian cancer with at least 1 grandparent born in the participating study sites were included; 1018 individuals were eligible and consented to participate in this study. Data were analyzed from November 4, 2019, to May 6, 2020.

EXPOSURES

Breast and/or ovarian cancer diagnosis.

MAIN OUTCOMES AND MEASURES

Rate of inherited breast and ovarian cancer syndrome and spectrum and types of variants.

RESULTS

Of 1018 participants, 999 (98.1%) had breast cancer (mean [SD] age, 46.6 [10.8] years) and 21 (2.1%) had ovarian cancer (mean [SD] age, 47.6 [13.5] years). Three individuals declined to have their results reported. A total of 144 of 1015 (14.2%) had a pathogenic or likely pathogenic (P/LP) variant in a hereditary breast and ovarian cancer syndrome gene. A total of 64% of variant carriers had P/LP variant in BRCA1, 23% in BRCA2, 9% in PALB2 and 4% in RAD51C, CHEK2, ATM, STK11 and NBN. The mean (SD) age of variant carriers was 40.7 (9.2) compared with 47.5 (10.7) years in noncarriers. Individuals in the Bahamas had the highest proportion of hereditary breast and ovarian cancer (23%), followed by Barbados (17.9%), Trinidad (12%), Dominica (8.8%), Haiti (6.7%), Cayman Islands (6.3%), and Jamaica (4.9%). In Caribbean-born women and men with breast cancer, having a first- or second-degree family member with breast cancer was associated with having any BRCA1 or BRCA2 germline variant (odds ratio, 1.58; 95% CI, 1.24-2.01; P < .001). A BRCA1 vs BRCA2 variant was more strongly associated with triple negative breast cancer (odds ratio, 6.33; 95% CI, 2.05-19.54; P = .001).

CONCLUSIONS AND RELEVANCE

In this study, among Caribbean-born individuals with breast and ovarian cancer, 1 in 7 had hereditary breast and ovarian cancer. The proportion of hereditary breast and ovarian cancer varied by island and ranged from 23% in the Bahamas to 4.9% in Jamaica. Each island had a distinctive set of variants.