Germline Genetic Testing: What the Breast Surgeon Needs to Know

Demographics and Clinical Decision Making in Patients with Germline Moderate Penetrance Non-BRCA Mutations in Breast Cancer Related Genes

BACKGROUND

Management of pathogenic variants in high penetrance genes related to breast cancer (BC), such as BRCA1 and BRCA2, are well established. However, moderate penetrance mutations are understudied. We aim to compare risk reduction decision-making patterns in patients with a moderate penetrance BC-related genetic mutations, without a prior BC diagnosis.

PATIENTS AND METHODS

Female patients aged ≥ 18 years who tested positive for a BRCA1/2, high penetrance, or moderate penetrance mutation related to BC between 1996 and 2023 without a concurrent or prior BC diagnosis were retrospectively identified from a single academic center's database. Groups were stratified by mutation type: BRCA1/2 mutations (BRCA1, BRCA2), high penetrance mutations (HPM; CDH1, PALB2, PTEN, STK11, TP53), or moderate penetrance mutations (MPM; ATM, BARD1, CHEK2, NF1, RAD51C, RAD51D). Demographics and clinical outcomes were compared.

RESULTS

A total of 528 patients met the inclusion criteria, with 66% (n = 350) having a BRCA1/2 mutation, 8% (n = 44) having HPM, and 25% (n = 134) having MPM; the median follow-up was 56.0 months. In our cohort, 20.9% of patients with BRCA mutations, 9.1% with HPM, and 7.5% with MPM chose to undergo risk-reducing mastectomies (RRM). Within the moderate penetrance cohort, patients who chose to undergo RRM were younger at the time of genetic testing (39.4 vs. 47.5 years, p = 0.03) and had a higher number of family members with BC (2 vs. 1, p = 0.05).

CONCLUSIONS

Our findings provide insights into the demographic characteristics and family history of patients with moderate penetrance mutations and those who pursue risk-reducing surgery.

Clinical genetics in breast cancer

As genetic testing becomes increasingly more accessible and more applicable with a broader range of clinical implications, it may also become more challenging for breast cancer providers to remain up-to-date. This review outlines some of the current clinical guidelines and recent literature surrounding germline genetic testing, as well as genomic testing, in the screening, prevention, diagnosis, and treatment of breast cancer, while identifying potential areas of further research.

Immunohistochemical findings and clinicopathological features of breast cancers with pathogenic germline mutations in Non-BRCA genes

Deleterious germline mutations in multiple genes confer an increased breast cancer (BC) risk. Immunohistochemical (IHC) expression of protein products of mutated high-risk genes has not been investigated in BC. We hypothesized that pathogenic mutations may lead to an abnormal IHC expression pattern in the tumor cells. BCs with deleterious germline mutations in CHEK2, ATM, PALB2 & PTEN were identified. Immunohistochemistry was performed using Dako staining platform on formalin fixed paraffin embedded tumor tissue. Primary antibodies for PALB2 (ab202970), ATM [2C1(1A10)}, CHK2 (EPR4325), and PTEN (138G6) proteins were used for BCs with respective deleterious mutations. IHC expression was assessed in tumor and adjacent benign breast tissue. Total 27 BCs with 10 CHEK2, 9 ATM, 6 PALB2 & 2 PTEN deleterious germline mutations were identified. IHC staining was performed on 8 CHEK2, 7 ATM, 6 PALB2 & 2 PTEN cases. Abnormal CHEK2 IHC staining was identified in 7/8(88%) BCs. Three distinct CHK2 IHC patterns were noted: 1) Strong diffuse nuclear positivity (5 BC), 2) Null-pattern (2 BC), & 3) Normal breast-like staining in 1 BC Four of 5 (80%) strong CHK2 staining BC had missense CHEK2 mutations. Null-pattern was present with a missense & a frameshift mutation. Normal breast-like CHEK2 IHC staining pattern was present in 1 BC with CHEK2 frameshift mutation. Loss of nuclear/cytoplasmic PTEN IHC expression was noted in 2 in-situ carcinomas. Abnormal PTEN and CHK2 IHC were present in atypical ductal hyperplasia and flat epithelial atypia. ATM and PALB2 IHC expression patterns were similar in tumor cells and benign breast epithelium: mild to moderate intensity nuclear and cytoplasmic staining. We report abnormal CHEK2 IHC expression in 88% of BCs with pathogenic CHEK2 mutations. With PTEN and CHEK2 pathogenic mutations, abnormal IHC patterns are seen in early atypical proliferative lesions. IHC may be applied to identify CHEK2 & PTEN mutated BCs and precursor lesions.

Breast Cancer Risk Assessment and Screening Practices Reported Via an Online Survey

BACKGROUND

Breast cancer screening guidelines differ between organizations, and significant variations in practice patterns exist. Previous evidence suggests that provider-level factors are the greatest contributors to risk assessment and screening practice variability. This study aimed to characterize provider factors associated with breast cancer risk assessment and screening practice patterns, and to assess perceived barriers to providing risk assessment.

METHODS

An online survey was distributed to providers at a single academic institution and to providers publicly via social media (January to August 2022). Respondents in the United States who care for adult women at risk for the development of breast cancer were included.

RESULTS

Most of the respondents in the 143 completed surveys were white/Caucasian (79%) females (90%) age 50 years or younger (79%), and whereas 97% discuss breast cancer screening with their patients, only 90% order screening mammograms. Risk factor assessment was common (93%), typically performed at the first visit (51%). Additional training in genetics or risk assessment was uncommon (17%), although the majority were interested but did not have the time or resources (55%). Although most (64%) did not perceive barriers to providing risk assessment or appropriate screening, the most common barriers were time (77%) and education (55%). Barriers were more common among family practice or obstetrics and gynecology (OB/GYN) providers and those who worked in an academic setting (all p < 0.05).

CONCLUSIONS

Breast cancer risk assessment and screening practices are highly variable. Although time is the major barrier to providing risk assessment, providers also need education. Primary care organizations could partner with breast cancer-focused societies for additional resources.

The Role of the Surgeon in the Germline Testing of the Newly Diagnosed Breast Cancer Patient

For patients with newly diagnosed breast cancer, information regarding hereditary predisposition can influence treatment decisions. From a surgical standpoint, patients with known germline mutations may alter decisions of local therapy to reduce the risk of second breast primaries. This information may also be considered in the choice of adjuvant therapies or eligibility for clinical trials. In recent years, the criteria for the consideration of germline testing in patients with breast cancer has expanded. Additionally, studies have shown a similar prevalence of pathogenic mutations in those patients outside of these traditional criteria, prompting calls for genetic testing for all patients with a history of breast cancer. While data confirms the benefit of counseling by certified genetics professionals, the capacity of genetic counselors may no longer meet the needs of these growing numbers of patients. National societies assert that counseling and testing can be performed by providers with training and experience in genetics. Breast surgeons are well positioned to offer this service, as they receive formal genetics training during their fellowship, manage these patients daily in their practices, and are often the first providers to see patients after their cancer diagnosis.

What can we learn from more than 1,000 Brazilian patients at risk of hereditary cancer?

Background

Identifying individuals at a higher risk of developing cancer is a major concern for healthcare providers. Cancer predisposition syndromes are the underlying cause of cancer aggregation and young-onset tumors in many families. Germline genetic testing is underused due to lack of access, but Brazilian germline data associated with cancer predisposition syndromes are needed.

Methods

Medical records of patients referred for genetic counseling at the Oncogenetics Department at the Hospital Sírio-Libanês (Brasília, DF, Brazil) from July 2017 to January 2021 were reviewed. The clinical features and germline findings were described. Detection rates of germline pathogenic/likely pathogenic variant (P/LPV) carriers were compared between international and Brazilian guidelines for genetic testing.

Results

A total of 1,091 individuals from 985 families were included in this study. Most patients (93.5%) had a family history of cancer, including 64% with a family member under 50 with cancer. Sixty-six percent of patients (720/1091) had a personal history of cancer. Young-onset cancers (<50 years old) represented 62% of the patients affected by cancer and 17% had multiple primary cancers. The cohort included patients with 30 different cancer types. Breast cancer was the most prevalent type of cancer (52.6%). Germline testing included multigene panel (89.3%) and family variant testing (8.9%). Approximately 27% (236/879) of the tested patients harbored germline P/LPVs in cancer susceptibility genes. BRCA2, BRCA1, and TP53 were the most frequently reported genes, corresponding to 18.6%, 14.4%, and 13.5% of the positive results, respectively. Genetic testing criteria from international guidelines were more effective in identifying carriers than the Brazilian National Agency of Supplementary Health (ANS) criteria (92% vs. 72%, p<0.001). Forty-six percent of the cancer-unaffected patients who harbored a germline P/LPV (45/98) would not be eligible for genetic testing according to ANS because they did not have a family variant previously identified in a cancer-affected relative.

Conclusion

The high detection rate of P/LPVs in the present study is possibly related to the genetic testing approach with multigene panels and cohort's characteristics, represented mainly by individuals with a personal or family history of young-onset cancer. Testing asymptomatic individuals with suspicious family history may also have contributed to a higher detection rate. A significant number of carriers would not have been identified using ANS criteria for genetic testing.

Timely cancer genetic counseling and testing for young women with breast cancer: impact on surgical decision-making for contralateral risk-reducing mastectomy

PURPOSE

Genetic testing (GT) can identify individuals with pathogenic/likely pathogenic variants (PV/LPVs) in breast cancer (BC) predisposition genes, who may consider contralateral risk-reducing mastectomy (CRRM). We report on CRRM rates in young women newly diagnosed with BC who received GT through a multidisciplinary clinic.

METHODS

Clinical data were reviewed for patients seen between November 2014 and June 2019. Patients with non-metastatic, unilateral BC diagnosed at age ≤ 45 and completed GT prior to surgery were included. Associations between surgical intervention and age, BC stage, family history, and GT results were evaluated.

RESULTS

Of the 194 patients, 30 (15.5%) had a PV/LPV in a BC predisposition gene (ATM, BRCA1, BRCA2, CHEK2, NBN, NF1), with 66.7% in BRCA1 or BRCA2. Of 164 (84.5%) uninformative results, 132 (68%) were negative and 32 (16.5%) were variants of uncertain significance (VUS). Overall, 67 (34.5%) had CRRM, including 25/30 (83.3%) PV/LPV carriers and 42/164 (25.6%) non-carriers. A positive test result (p < 0.01) and significant family history were associated with CRRM (p = 0.02). For the 164 with uninformative results, multivariate analysis showed that CRRM was not associated with age (p = 0.23), a VUS, (p = 0.08), family history (p = 0.10), or BC stage (p = 0.11).

CONCLUSION

In this cohort of young women with BC, the identification of a PV/LPV in a BC predisposition gene and a significant family history were associated with the decision to pursue CRRM. Thus, incorporation of genetic services in the initial evaluation of young patients with a new BC could contribute to the surgical decision-making process.

Attitudes and training needs of oncologists and surgeons in mainstreaming breast cancer genetic counseling in a low-to-middle income Asian country

With the advent of poly-ADP-ribose polymerase inhibitor (PARPi) therapies, the focus of genetic testing for breast, ovarian, and other cancers has shifted from risk management to treatment decision-making in high-resource settings. Due to the shortage of genetic counselors worldwide, alternative ways of delivering genetic counseling have been explored, including training nongenetics healthcare professionals (NGHPs) to provide genetic counseling. However, little is known about the feasibility of adopting such models in healthcare settings with insufficient specialists, where population health literacy is low and where access to new therapies may be limited. In this study, we evaluated the attitudes, considerations, and self-efficacy of oncologists, breast surgeons, and general surgeons in mainstreaming breast cancer genetic counseling in Malaysia, a middle-income Asian country with a universal healthcare system. We developed a 32-item survey via a modified Delphi method, which was then distributed via a purposive and network sampling approach. While 77% of respondents expressed interest in providing breast cancer genetic counseling, 85% preferred to refer patients directly to genetic services for genetic counseling and testing. The main considerations for mainstreaming were the cost of genetic testing and PARPi therapy, as well as the availability of support from genetics professionals. Respondents reported a lack of confidence in communicating genetic risk, particularly to patients with poor health literacy, and in the clinical management of patients with variants of uncertain significance. Our results highlight the urgent need to train more NGHPs in providing genetic counseling and testing in low-to-middle income countries, and suggest that the mainstay for genetic counseling in this setting may be for risk management rather than access to PARPi therapy.

Demographic Barriers for Genetic Testing in High-Risk Breast Cancer Patients in the Northern Michigan Area

Introduction: The National Comprehensive Cancer Network (NCCN) has outlined guidelines for criteria regarding genetic testing for high-penetrance breast and/or ovarian cancer susceptibility genes. Due to the lack of availability of genetic counseling services in Northern Michigan prior to COVID-19, the utilization of genetic testing falls well below recommended guidelines.

Methods: Patients diagnosed with breast cancer in 2019 were randomly selected from Ascension Michigan's Northern Ministries Tumor Registry. A retrospective chart review was conducted. For patients who met NCCN criteria, their medical records were used to determine if genetic testing was recommended and if genetic testing was completed. Univariate (Crosstabs and t-tests) and multivariate tests with logistic regression were used to identify significant associations between the variables of interest.

Results: One hundred and two (102) patient charts were reviewed in this group; 55 (52.4%) were eligible by the NCCN guidelines for genetic testing. From this eligible subset of patients, only 29 were offered genetic testing, and only 21 were tested. The mean age of the patients offered genetic counseling was 56.2 years compared and 67.6 years in the group not offered counseling (p < 0.001). The patient's insurance type was an independent factor for obtaining genetic testing, specifically, the subgroup who had Medicare (OR = 0.73, CI = 0.01-0.54; p = 0.02). Patients insured through Medicare were less likely to obtain genetic testing after referral to a genetic counselor (p = 0.01).

Conclusion: Genetic counseling for high-risk breast cancer patients is below average in Northern Michigan, likely related to lack of physician referral, poor availability of counseling services, low socioeconomic status as well as a lower level of concern in older ages.

Utilization of genetic testing: Analysis of 4,499 prior authorization requests for molecular genetic tests at four US regional health plans

Continuous advances in genetic testing methodologies and an increased understanding of the genetic mechanisms of diseases have fueled genetic testing utilization across health care specialties. To our knowledge, national trends in the ordering of genetic testing have not been studied broadly across clinical indications, testing methodologies, and ordering provider specialties. We performed a retrospective analysis of 4,499 complete prior authorization requests for molecular genetic testing submitted to four regional health plans' commercial lines of business between May 1, 2019 and May 31, 2019. Ordering providers were characterized by their certification(s) and specialty of practice. Among 4,499 genetic testing requests, 92% were ordered by non-genetics providers. Obstetrician/gynecology (OBGYN) (63%), oncology (15%), and genetics (8%) providers ordered genetic testing most frequently. Reproductive, hereditary cancer, and tumor testing were the most frequently ordered genetic tests. Seventy-nine percent of all prior authorization requests were approved. When analyzing complex genetic testing requests, we found that testing ordered by genetics providers was more likely to be approved based on health plan policy than testing ordered by non-genetics providers. Our results suggest that health care providers across multiple medical specialties may benefit from involvement of genetics specialists in decision-making regarding molecular tests.

Disparities in Genetic Testing for Heritable Solid-Tumor Malignancies

Genetic testing offers providers a potentially life saving tool for identifying and intervening in high-risk individuals. However, disparities in receipt of genetic testing have been consistently demonstrated and undoubtedly have significant implications for the populations not receiving the standard of care. If correctly used, there is the potential for genetic testing to play a role in decreasing health disparities among individuals of different races and ethnicities. However, if genetic testing continues to revolutionize cancer care while being disproportionately distributed, it also has the potential to widen the existing mortality gap between various racial and ethnic populations.

The Community Oncology and Academic Medical Center Alliance in the Age of Precision Medicine: Cancer Genetics and Genomics Considerations

Recent public policy, governmental regulatory and economic trends have motivated the establishment and deepening of community health and academic medical center alliances. Accordingly, community oncology practices now deliver a significant portion of their oncology care in association with academic cancer centers. In the age of precision medicine, this alliance has acquired critical importance; novel advances in nucleic acid sequencing, the generation and analysis of immense data sets, the changing clinical landscape of hereditary cancer predisposition and ongoing discovery of novel, targeted therapies challenge community-based oncologists to deliver molecularly-informed health care. The active engagement of community oncology practices with academic partners helps with meeting these challenges; community/academic alliances result in improved cancer patient care and provider efficacy. Here, we review the community oncology and academic medical center alliance. We examine how practitioners may leverage academic center precision medicine-based cancer genetics and genomics programs to advance their patients' needs. We highlight a number of project initiatives at the City of Hope Comprehensive Cancer Center that seek to optimize community oncology and academic cancer center precision medicine interactions.

Cancer Genetic Counseling-Current Practice and Future Challenges

Cancer genetic counseling practice is rapidly evolving, with services being provided in increasingly novel ways. Pretest counseling for cancer patients may be abbreviated from traditional models to cover the elements of informed consent in the broadest of strokes. Genetic testing may be ordered by a cancer genetics professional, oncology provider, or primary care provider. Increasingly, direct-to-consumer testing options are available and utilized by consumers anxious to take control of their genetic health. Finally, genetic information is being used to inform oncology care, from surgical decision-making to selection of chemotherapeutic agent. This review provides an overview of the current and evolving practice of cancer genetic counseling as well as opportunities and challenges for a wide variety of indications in both the adult and pediatric setting.

Legacy Genetic Testing Results for Cancer Susceptibility: How Common are Conflicting Classifications in a Large Variant Dataset from Multiple Practices?

PURPOSE

The classification of germline variants may differ between labs and change over time. We apply a variant harmonization tool, Ask2Me VarHarmonizer, to map variants to ClinVar and identify discordant variant classifications in a large multipractice variant dataset.

METHODS

A total of 7496 variants sequenced between 1996 and 2019 were collected from 11 clinical practices. Variants were mapped to ClinVar, and lab-reported and ClinVar variant classifications were analyzed and compared.

RESULTS

Of the 4798 unique variants identified, 3699 (77%) were mappable to ClinVar. Among mappable variants, variants of unknown significance (VUS) accounted for 74% of lab-reported classifications and 60% of ClinVar classifications. Lab-reported and ClinVar discordances were present in 783 unique variants (21.2% of all mappable variants); 121 variants (2.5% of all unique variants) had within-practice lab-reported discordances; and 56 variants (1.2% of all unique variants) had lab-reported discordances across practices. The unmappable variants were associated with a higher proportion of lab-reported pathogenic classifications (50% vs. 21%, p < 0.0001) and a lower proportion of lab-reported VUS classifications (46% vs. 74%, p < 0.0001).

CONCLUSIONS

Our study shows that discordant variant classification occurs frequently, which may lead to inappropriate recommendations for prophylactic treatments or clinical management.

Current Approaches to Germline Cancer Genetic Testing

The prevalence of genetic predisposition to cancer is greater than initially appreciated, yet most affected individuals remain undiagnosed. Deleterious germline variants in cancer predisposition genes are implicated in 1 in 10 cases of advanced cancer. Next-generation sequencing technologies have made germline and tumor DNA sequencing more accessible and less expensive. Expanded access to clinical genetic testing will improve identification of individuals with genetic predisposition to cancer and provide opportunities to effectively reduce morbidity through precision cancer therapies and surveillance. Cross-disciplinary clinical education in genomic medicine is needed to translate advances in genomic medicine into improved health outcomes.

Natural language processing to facilitate breast cancer research and management

The medical literature has been growing exponentially, and its size has become a barrier for physicians to locate and extract clinically useful information. As a promising solution, natural language processing (NLP), especially machine learning (ML)-based NLP is a technology that potentially provides a promising solution. ML-based NLP is based on training a computational algorithm with a large number of annotated examples to allow the computer to "learn" and "predict" the meaning of human language. Although NLP has been widely applied in industry and business, most physicians still are not aware of the huge potential of this technology in medicine, and the implementation of NLP in breast cancer research and management is fairly limited. With a real-world successful project of identifying penetrance papers for breast and other cancer susceptibility genes, this review illustrates how to train and evaluate an NLP-based medical abstract classifier, incorporate it into a semiautomatic meta-analysis procedure, and validate the effectiveness of this procedure. Other implementations of NLP technology in breast cancer research, such as parsing pathology reports and mining electronic healthcare records, are also discussed. We hope this review will help breast cancer physicians and researchers to recognize, understand, and apply this technology to meet their own clinical or research needs.

Consensus Guidelines on Genetic` Testing for Hereditary Breast Cancer from the American Society of Breast Surgeons

BACKGROUND

The purpose of this consensus guideline is to outline recommendations for genetic testing that medical professionals can use to assess hereditary risk for breast cancer.

METHODS

Literature review included large datasets, basic and clinical science publications, and recent updated national guidelines. Genetic testing to assess hereditary risk of cancer is a complex, broad, and dynamic area of medical research. The dominant focus of this guideline is limited in scope to breast cancer.

RESULTS

There is a lack of consensus among experts regarding which genes among many should be tested in different clinical scenarios. There is also variation in the degree of consensus regarding the understanding of risk and appropriate clinical management of mutations in many genes.

CONCLUSIONS

Genetic testing should be made available to all patients with a personal history of breast cancer. Recent data are reviewed that support genetic testing being offered to each patient with breast cancer (newly diagnosed or with a personal history). If genetic testing is performed, such testing should include BRCA1/BRCA2 and PALB2, with other genes as appropriate for the clinical scenario and family history. For patients with newly diagnosed breast cancer, identification of a mutation may impact local treatment recommendations. Patients who had genetic testing previously may benefit from updated testing. Genetic testing should be made available to patients without a history of breast cancer who meet National Comprehensive Cancer Network guidelines. Finally, variants of uncertain significance are not clinically actionable and these patients should be managed based on their individual risk factors.