Adaptation of the socioecological model to address disparities in engagement of Black men in prostate cancer genetic testing.

BACKGROUND: Black men consistently have higher rates of prostate cancer (PCA)- related mortality. Advances in PCA treatment, screening, and hereditary cancer assessment center around germline testing (GT). Of concern is the significant under-engagement of Black males in PCA GT, limiting the benefit of precision therapy and tailored cancer screening despite longstanding awareness of these disparities. To address these critical disparities, the Socioecological Model (SEM) was employed to develop comprehensive recommendations to overcome barriers and implement equitable strategies to engage Black males in PCA GT. METHODS: Clinical/research experts, national organization leaders, and community stakeholders spanning multiple regions in US and Africa participated in developing a framework for equity in PCA GT grounded in the SEM. A novel mixed-methods approach was employed to generate key areas to be addressed and informed statements for consensus consideration utilizing the modified Delphi model. Statements achieving strong consensus (> =75% agreement) were included in final equity frameworks addressing clinical/community engagement and research engagement. RESULTS: All societal levels of the SEM (interpersonal, institutional, community, and policy/advocacy) must deliver information about PCA GT to Black males that address benefits/limitations, clinical impact, hereditary cancer implications, with acknowledgment of mistrust (mean scores [MS] 4.57-5.00). Interpersonal strategies for information delivery included engagement of family/friends/peers/Black role models to improve education/awareness and overcome mistrust (MS 4.65-5.00). Institutional strategies included diversifying clinical, research, and educational programs and integrating community liaisons into healthcare institutions (MS 4.57-5.00). Community strategies included partnerships with healthcare institutions and visibility of healthcare providers/researchers at community events (MS 4.65-4.91). Policy/advocacy included improving partnerships between advocacy and healthcare/community organizations while protecting patient benefits (MS 4.57-5.00). Media strategies were endorsed for the first time at every level (MS 4.56-5.00). CONCLUSION: The SEM-based equity frameworks proposed provide the first multidisciplinary strategies dedicated to increase engagement of Black males in PCA GT, which are critical to reduce disparities in PCA-mortality through informing tailored screening, targeted therapy, and cascade testing in families.

Tumor suppressor heterozygosity and homologous recombination deficiency mediate resistance to front-line therapy in breast cancer.

The co-occurrence of germline and somatic oncogenic alterations is frequently observed in breast cancer, but their combined biologic and clinical significance has not been evaluated. To assess the role of germline-somatic interactions on outcomes in routine practice, we developed an integrated clinicogenomic pipeline to analyze the genomes of over 4,500 patients with breast cancer. We find that germline (g) BRCA2 -associated tumors are enriched for RB1 loss-of-function mutations and manifest poor outcomes on standard-of-care, front-line CDK4/6 inhibitor (CDK4/6i) combinations. Amongst these tumors, g BRCA2 -related homologous recombination deficiency (HRD) as well as baseline RB1 LOH status promote acquisition of RB1 loss-of- function mutations under the selective pressure of CDK4/6i, causing therapy resistance. These findings suggest an alternative therapeutic strategy using sequential targeting of HRD in g BRCA- associated breast cancers through PARP inhibitors prior to CDK4/6i therapy to intercept deleterious RB1 -loss trajectories and thus suppress the emergence of CDK4/6 inhibitor resistance. More broadly, our findings demonstrate how germline-somatic driven genomic configurations shape response to systemic therapy and can be exploited therapeutically as part of biomarker-directed clinical strategies.

Radiation-Associated Secondary Cancer in Patients With Breast Cancer Harboring TP53 Germline Variants.

This cohort study examines the risk of radiation-associated sarcoma in patients with breast cancer harboring germline TP53 variants.

Assessing olaparib efficacy in U.S. Veterans with metastatic prostate cancer utilizing a time-indifferent g-rate method ideal for real-world analyses.

BACKGROUND: We aimed to assess real-world efficacy of the PARP inhibitor, olaparib, in US Veterans with metastatic prostate cancer (mPC) by leveraging the national data repository and evaluate a novel approach to assess treatment efficacy in tumors considered rare or harboring rare mutations. METHODS: Included Veterans had 1) mPC with somatic or germline alterations/mutations in genes involved in homologous recombination repair (HRR), 2) received olaparib monotherapy as well as a novel hormonal therapy/androgen receptor pathway inhibitors (NHT/ARPI), and/or chemotherapy, and 3) estimable rates of tumor growth (g-rate) using PSA values obtained while receiving treatment. Previous work has shown an excellent inverse correlation of g-rate with survival. Using g-rate, we determined tumor doubling time (DT) and DT ratios (DT on olaparib/DT on prior medication). We postulated that a DT ratio≥ 1 was associated with benefit. FINDINGS: We identified 139 Veterans, including 42 Black males with tumors harboring mutations/alterations in HRR genes who received olaparib: BRCA2 (50), ATM (32), BRCA1 (10), other mutations (47). 62/139 (45%) of all and 21/42 (50%) of Black Veterans had DT ratios ≥1, including 31, 10, 2, and 19 with BRCA2, ATM, BRCA1, and other mutations, respectively (p = 0.006). Median survival with DT ratios ≥1 was superior, being 24.5 vs. 11.4 months for DT ratio <1 (p = 0.01, HR 0.50, 95% CI 0.29-0.85). Benefit from olaparib, defined as DT ratio ≥1, was not observed for germline status, starting PSA value, number of prior therapies, or immediate prior therapy. Compared to matched cohorts, tumors in the olaparib cohort had shorter DTs with enzalutamide in first line (367 vs. 884 days; p = 0.0043). INTERPRETATION: Using equations indifferent to timing of assessments ideal for real-world efficacy analyses, we showed DT ratio ≥1 representing slower tumor growth on olaparib relative to the prior therapy correlates with improved survival. Olaparib efficacy in Veterans with mPC harboring mutations/alterations in HRR genes emulates clinical trial results. Black men had comparable results. Compared to matched cohorts, in first line, enzalutamide was less efficacious in tumors harboring mutations/alterations in HRR genes. FUNDING: American Society of Clinical Oncology Conquer Cancer Foundation (ASCO CCF), the Blavatnik Family Foundation and the Prostate Cancer Foundation (PCF).

Update on Pediatric Cancer Surveillance Recommendations for Patients with Neurofibromatosis Type 1, Noonan Syndrome, CBL Syndrome, Costello Syndrome, and Related RASopathies.

Neurofibromatosis type 1 (NF1), Noonan syndrome and related syndromes, grouped as the RASopathies, result from dysregulation of the RAS-MAPK pathway and demonstrate varied multisystemic clinical phenotypes. Together the RASopathies are among the more prevalent genetic cancer predisposition syndromes and require nuanced clinical management. When compared to the general population, children with RASopathies are at significantly increased risk of benign and malignant neoplasms. In the last decade, clinical trials have shown that targeted therapies can improve outcomes for low-grade and benign neoplastic lesions but have their own challenges, highlighting the multi-disciplinary care needed for such individuals, specifically those with NF1. This perspective, which originated from the 2023 AACR Childhood Cancer Predisposition Workshop, serves to update pediatric oncologists, neurologists, geneticists, counselors, and other healthcare professionals on revised diagnostic criteria, review previously published surveillance guidelines, and harmonize updated surveillance recommendations for patients with NF1 or RASopathies.

BRCA1, BRCA2, and Associated Cancer Risks and Management for Male Patients: A Review.

Importance: Half of all carriers of inherited cancer-predisposing variants in BRCA1 and BRCA2 are male, but the implications for their health are underrecognized compared to female individuals. Germline variants in BRCA1 and BRCA2 (also known as pathogenic or likely pathogenic variants, referred to here as BRCA1/2 PVs) are well known to significantly increase the risk of breast and ovarian cancers in female carriers, and knowledge of BRCA1/2 PVs informs established cancer screening and options for risk reduction. While risks to male carriers of BRCA1/2 PVs are less characterized, there is convincing evidence of increased risk for prostate cancer, pancreatic cancer, and breast cancer in males. There has also been a rapid expansion of US Food and Drug Administration-approved targeted cancer therapies, including poly ADP ribose polymerase (PARP) inhibitors, for breast, pancreatic, and prostate cancers associated with BRCA1/2 PVs. Observations: This narrative review summarized the data that inform cancer risks, targeted cancer therapy options, and guidelines for early cancer detection. It also highlighted areas of emerging research and clinical trial opportunities for male BRCA1/2 PV carriers. These developments, along with the continued relevance to family cancer risk and reproductive options, have informed changes to guideline recommendations for genetic testing and strengthened the case for increased genetic testing for males. Conclusions and Relevance: Despite increasing clinical actionability for male carriers of BRCA1/2 PVs, far fewer males than female individuals undergo cancer genetic testing. Oncologists, internists, and primary care clinicians should be vigilant about offering appropriate genetic testing to males. Identifying more male carriers of BRCA1/2 PVs will maximize opportunities for cancer early detection, targeted risk management, and cancer treatment for males, along with facilitating opportunities for risk reduction and prevention in their family members, thereby decreasing the burden of hereditary cancer.

Identification of TP53 germline variants in pediatric patients undergoing tumor testing: strategy and prevalence.

BACKGROUND: TP53 alterations are common in certain pediatric cancers, making identification of putative germline variants through tumor genomic profiling crucial for disease management. METHODS: We analyzed TP53 alterations in 3123 tumors from 2788 pediatric patients sequenced using tumor-only or tumor-normal paired panels. Germline confirmatory testing was performed when indicated. Somatic and germline variants were classified based on published guidelines. RESULTS: In 248 tumors from 222 patients, 284 tier 1/2 TP53 sequence and small copy number variants were detected. Following germline classification, 86.6% of 142 unique variants were pathogenic or likely pathogenic. Confirmatory testing on 118 patients revealed germline TP53 variants in 28 of them (23 pathogenic or likely pathogenic and 5 of uncertain significance), suggesting a minimum Li-Fraumeni syndrome incidence of 0.8% (23/2788) in this cohort, 10.4% (23/222) in patients with TP53 variant-carrying tumors, and 19.5% (23/118) with available normal samples. About 25% (7/28) of patients with germline TP53 variants did not meet Li-Fraumeni syndrome diagnostic or testing criteria, while 20.9% (28/134) with confirmed or inferred somatic origins did. TP53 biallelic inactivation occurred in 75% of germline carrier tumors and was also prevalent in other groups, causing an elevated tumor-observed variant allelic fraction. Somatic evidence, however, including low variant allele fraction correctly identified only 27.8% (25/90) of patients with confirmed somatic TP53 variants. CONCLUSION: The high incidence and variable phenotype of Li-Fraumeni syndrome in this cohort highlights the importance of assessing germline status of TP53 variants identified in all pediatric tumors. Without clear somatic evidence, distinguishing somatic from germline origins is challenging. Classifying germline and somatic variants should follow appropriate guidelines.

Racial Differences in Germline Genetic Testing Completion Among Males With Pancreatic, Breast, or Metastatic Prostate Cancers.

BACKGROUND: Germline genetic testing is a vital component of guideline-recommended cancer care for males with pancreatic, breast, or metastatic prostate cancers. We sought to determine whether there were racial disparities in germline genetic testing completion in this population. PATIENTS AND METHODS: This retrospective cohort study included non-Hispanic White and Black males with incident pancreatic, breast, or metastatic prostate cancers between January 1, 2019, and September 30, 2021. Two nationwide cohorts were examined: (1) commercially insured individuals in an administrative claims database, and (2) Veterans receiving care in the Veterans Health Administration. One-year germline genetic testing rates were estimated by using Kaplan-Meier methods. Cox proportional hazards regression was used to test the association between race and genetic testing completion. Causal mediation analyses were performed to investigate whether socioeconomic variables contributed to associations between race and germline testing. RESULTS: Our cohort consisted of 7,894 males (5,142 commercially insured; 2,752 Veterans). One-year testing rates were 18.0% (95% CI, 16.8%-19.2%) in commercially insured individuals and 14.2% (95% CI, 11.5%-15.0%) in Veterans. Black race was associated with a lower hazard of testing among commercially insured individuals (adjusted hazard ratio [aHR], 0.73; 95% CI, 0.58-0.91; P=.005) but not among Veterans (aHR, 0.99; 95% CI, 0.75-1.32; P=.960). In commercially insured individuals, income (aHR, 0.90; 95% CI, 0.86-0.96) and net worth (aHR, 0.92; 95% CI, 0.86-0.98) mediated racial disparities, whereas education (aHR, 0.98; 95% CI, 0.94-1.01) did not. CONCLUSIONS: Overall rates of guideline-recommended genetic testing are low in males with pancreatic, breast, or metastatic prostate cancers. Racial disparities in genetic testing among males exist in a commercially insured population, mediated by net worth and household income; these disparities are not seen in the equal-access Veterans Health Administration. Alleviating financial and access barriers may mitigate racial disparities in genetic testing.

Prevalence of H. pylori and Gastric Intestinal Metaplasia in BRCA1 and BRCA2 Carriers.

BRCA1 and BRCA2 carriers may be at increased risk for gastric cancer; however, the mechanisms of gastric carcinogenesis remain poorly understood. We sought to determine the prevalence of gastric cancer risk factors Helicobacter pylori (H. pylori) infection and gastric intestinal metaplasia (GIM) among BRCA1/2 carriers to gain insight into the pathogenesis of gastric cancer in this population. A total of 100 unselected BRCA1/2 carriers who underwent endoscopic ultrasound from March 2022 to March 2023 underwent concomitant upper endoscopy with nontargeted gastric antrum and body biopsies. The study population (70% women; mean age 60.1 years) included 66% BRCA2 carriers. H. pylori was detected in one (1%) individual, 7 (7%) had GIM, 2 (2%) had autoimmune atrophic gastritis, and no gastric cancers were diagnosed. Among BRCA1/2 carriers, H. pylori prevalence was low and GIM prevalence was similar to that in the general population; however, identification of H. pylori or GIM may help inform future gastric cancer risk management strategies in BRCA1/2 carriers. Prevention Relevance: Evaluating the burden of H. pylori infection and GIM among BRCA1/2 carriers is warranted to better understand the mechanisms of gastric carcinogenesis and to help inform risk management strategies for gastric cancer among this at-risk population.

Disrupting prostate cancer research: Challenge accepted; report from the 2023 Coffey-Holden Prostate Cancer Academy Meeting.

INTRODUCTION: The 2023 Coffey-Holden Prostate Cancer Academy (CHPCA) Meeting, themed "Disrupting Prostate Cancer Research: Challenge Accepted," was convened at the University of California, Los Angeles, Luskin Conference Center, in Los Angeles, CA, from June 22 to 25, 2023. METHODS: The 2023 marked the 10th Annual CHPCA Meeting, a discussion-oriented scientific think-tank conference convened annually by the Prostate Cancer Foundation, which centers on innovative and emerging research topics deemed pivotal for advancing critical unmet needs in prostate cancer research and clinical care. The 2023 CHPCA Meeting was attended by 81 academic investigators and included 40 talks across 8 sessions. RESULTS: The central topic areas covered at the meeting included: targeting transcription factor neo-enhancesomes in cancer, AR as a pro-differentiation and oncogenic transcription factor, why few are cured with androgen deprivation therapy and how to change dogma to cure metastatic prostate cancer without castration, reducing prostate cancer morbidity and mortality with genetics, opportunities for radiation to enhance therapeutic benefit in oligometastatic prostate cancer, novel immunotherapeutic approaches, and the new era of artificial intelligence-driven precision medicine. DISCUSSION: This article provides an overview of the scientific presentations delivered at the 2023 CHPCA Meeting, such that this knowledge can help in facilitating the advancement of prostate cancer research worldwide.

Distinct genomic and immunologic tumor evolution in germline TP53-driven breast cancers.

Pathogenic germline TP53 alterations cause Li-Fraumeni Syndrome (LFS), and breast cancer is the most common cancer in LFS females. We performed first of its kind multimodal analysis of LFS breast cancer (LFS-BC) compared to sporadic premenopausal BC. Nearly all LFS-BC underwent biallelic loss of TP53 with no recurrent oncogenic variants except ERBB2 (HER2) amplification. Compared to sporadic BC, in situ and invasive LFS-BC exhibited a high burden of short amplified aneuploid segments (SAAS). Pro-apoptotic p53 target genes BAX and TP53I3 failed to be up-regulated in LFS-BC as was seen in sporadic BC compared to normal breast tissue. LFS-BC had lower CD8+ T-cell infiltration compared to sporadic BC yet higher levels of proliferating cytotoxic T-cells. Within LFS-BC, progression from in situ to invasive BC was marked by an increase in chromosomal instability with a decrease in proliferating cytotoxic T-cells. Our study uncovers critical events in mutant p53-driven tumorigenesis in breast tissue.

Clinical management of TP53 mosaic variants found on germline genetic testing.

BACKGROUND: Germline heterozygous TP53 pathogenic variants (PVs) cause Li Fraumeni Syndrome (LFS, OMIM#151623). TP53 PVs at lower-than-expected variant allele frequencies (VAF) may reflect postzygotic mosaicism (PZM) or clonal hematopoiesis (CH); however, no guidelines exist for workup and clinical management. PATIENTS AND METHODS: Retrospective analysis of probands who presented to an academic cancer genetics program with a TP53 PV result on germline genetic testing. RESULTS: Twenty-one of 125 unrelated probands (17 %) were found to harbor a TP53 PV with VAF<30 % or a designation of "mosaic". A diagnosis of PZM was made in nine (43 %) due to a clinical phenotype consistent with LFS with (n = 8) or without (n = 1) positive ancillary tissue testing. Twelve patients (57 %) were diagnosed with presumed CH (pCH) due to a diagnosis of a myeloproliferative neoplasm, negative ancillary tissue testing, clinical phenotype not meeting LFS criteria, no cancer, and/or no first cancer age<50. Of the 19 patients with biological offspring, nine had either partial or complete offspring testing, all negative. CONCLUSIONS: Determining the etiology of low VAF TP53 PVs requires ancillary tissue testing and incorporation of clinical phenotype. Discerning PZM versus CH is important to provide optimal care and follow-up.

Neighborhood Deprivation, Race and Ethnicity, and Prostate Cancer Outcomes Across California Health Care Systems.

Importance: Non-Hispanic Black (hereafter, Black) individuals experience worse prostate cancer outcomes due to socioeconomic and racial inequities of access to care. Few studies have empirically evaluated these disparities across different health care systems. Objective: To describe the racial and ethnic and neighborhood socioeconomic status (nSES) disparities among residents of the same communities who receive prostate cancer care in the US Department of Veterans Affairs (VA) health care system vs other settings. Design, Setting, and Participants: This cohort study obtained data from the VA Central Cancer Registry for veterans with prostate cancer who received care within the VA Greater Los Angeles Healthcare System (VA cohort) and from the California Cancer Registry (CCR) for nonveterans who received care outside the VA setting (CCR cohort). The cohorts consisted of all males with incident prostate cancer who were living within the same US Census tracts. These individuals received care between 2000 and 2018 and were followed up until death from any cause or censoring on December 31, 2018. Data analyses were conducted between September 2022 and December 2023. Exposures: Health care setting, self-identified race and ethnicity (SIRE), and nSES. Main Outcomes and Measures: The primary outcome was all-cause mortality (ACM). Cox proportional hazards regression models were used to estimate hazard ratios for associations of SIRE and nSES with prostate cancer outcomes in the VA and CCR cohorts. Results: Included in the analysis were 49 461 males with prostate cancer. Of these, 1881 males were in the VA cohort (mean [SD] age, 65.3 [7.7] years; 833 Black individuals [44.3%], 694 non-Hispanic White [hereafter, White] individuals [36.9%], and 354 individuals [18.8%] of other or unknown race). A total of 47 580 individuals were in the CCR cohort (mean [SD] age, 67.0 [9.6] years; 8183 Black individuals [17.2%], 26 206 White individuals [55.1%], and 13 191 individuals [27.8%] of other or unknown race). In the VA cohort, there were no racial disparities observed for metastasis, ACM, or prostate cancer-specific mortality (PCSM). However, in the CCR cohort, the racial disparities were observed for metastasis (adjusted odds ratio [AOR], 1.36; 95% CI, 1.22-1.52), ACM (adjusted hazard ratio [AHR], 1.13; 95% CI, 1.04-1.24), and PCSM (AHR, 1.15; 95% CI, 1.05-1.25). Heterogeneity was observed for the racial disparity in ACM in the VA vs CCR cohorts (AHR, 0.90 [95% CI, 0.76-1.06] vs 1.13 [95% CI, 1.04-1.24]; P = .01). No evidence of nSES disparities was observed for any prostate cancer outcomes in the VA cohort. However, in the CCR cohort, heterogeneity was observed for nSES disparities with ACM (AHR, 0.82; 95% CI, 0.80-0.84; P = .002) and PCSM (AHR, 0.86; 95% CI, 0.82-0.89; P = .007). Conclusions and Relevance: Results of this study suggest that racial and nSES disparities were wider among patients seeking care outside of the VA health care system. Health systems-related interventions that address access barriers may mitigate racial and socioeconomic disparities in prostate cancer.

Adult-Onset Cancer Predisposition Syndromes in Children and Adolescents-To Test or not to Test?

With the increasing use of comprehensive germline genetic testing of children and adolescents with cancer, it has become evident that pathogenic variants (PV) in adult-onset cancer predisposition genes (aoCPG) underlying adult-onset cancer predisposition syndromes, such as Lynch syndrome or hereditary breast and ovarian cancer, are enriched and reported in 1% to 2% of children and adolescents with cancer. However, the causal relationship between PVs in aoCPGs and childhood cancer is still under investigation. The best-studied examples include heterozygous PVs in mismatch repair genes associated with Lynch syndrome in children with mismatch repair deficient high-grade glioma, heterozygous PVs in BARD1 in childhood neuroblastoma, and heterozygous PVs in BRCA2 in children with rhabdomyosarcoma. The low penetrance for pediatric cancers is considered to result from a combination of the low baseline risk of cancer in childhood and the report of only a modest relative risk of disease in childhood. Therefore, we do not advise that healthy children empirically be tested for PVs in an aoCPG before adulthood outside a research study. However, germline panel testing is increasingly being performed in children and adolescents with cancer, and exome and genome sequencing may be offered more commonly in this population in the future. The precise pediatric cancer risks and spectra associated with PVs in aoCPGs, underlying cellular mechanisms and somatic mutational signatures, as well as treatment response, second neoplasm risks, and psycho-oncological aspects require further research.

Is It Time to Incorporate Liquid Biopsy into High-Risk Cancer Surveillance Protocols in Li-Fraumeni Syndrome?

SUMMARY: In the first prospective study evaluating circulating tumor DNA (ctDNA) for early cancer detection, Wong, Luo, and colleauges demonstrate the feasibility of liquid biopsy as an augmentation to current surveillance protocols for patients with Li-Fraumeni syndrome, an inherited cancer predisposition associated with high cancer risk in both pediatric and adult populations. Though additional clinical validation in larger cohorts is needed, this research highlights that a multimodal approach is likely necessary to improve the sensitivity of liquid biopsy assays for early cancer detection. See related article by Wong, Lou et al., p. 104 (9).

Germline pathogenic variants in neuroblastoma patients are enriched in BARD1 and predict worse survival.

BACKGROUND: Neuroblastoma is an embryonal cancer of the developing sympathetic nervous system. The genetic contribution of rare pathogenic or likely pathogenic germline variants in patients without a family history remains unclear. METHODS: Germline DNA sequencing was performed on 786 neuroblastoma patients. The frequency of rare cancer predisposition gene pathogenic or likely pathogenic variants in patients was compared with 2 cancer-free control cohorts. Matched tumor DNA sequencing was evaluated for second hits, and germline DNA array data from 5585 neuroblastoma patients and 23 505 cancer-free control children were analyzed to identify rare germline copy number variants. Patients with germline pathogenic or likely pathogenic variants were compared with those without to test for association with clinical characteristics, tumor features, and survival. RESULTS: We observed 116 pathogenic or likely pathogenic variants involving 13.9% (109 of 786) of neuroblastoma patients, representing a statistically significant excess burden compared with cancer-free participants (odds ratio [OR] = 1.60, 95% confidence interval [CI] = 1.27 to 2.00). BARD1 harbored the most statistically significant enrichment of pathogenic or likely pathogenic variants (OR = 32.30, 95% CI = 6.44 to 310.35). Rare germline copy number variants disrupting BARD1 were identified in patients but absent in cancer-free participants (OR = 29.47, 95% CI = 1.52 to 570.70). Patients harboring a germline pathogenic or likely pathogenic variant had a worse overall survival compared with those without (P = 8.6 x 10-3). CONCLUSIONS: BARD1 is an important neuroblastoma predisposition gene harboring both common and rare germline pathogenic or likely pathogenic variations. The presence of any germline pathogenic or likely pathogenic variant in a cancer predisposition gene was independently predictive of worse overall survival. As centers move toward paired tumor-normal sequencing at diagnosis, efforts should be made to centralize data and provide an infrastructure to support cooperative longitudinal prospective studies of germline pathogenic variation.

Genome-first approach of the prevalence and cancer phenotypes of pathogenic or likely pathogenic germline TP53 variants.

Pathogenic or likely pathogenic (P/LP) germline TP53 variants are the primary cause of Li-Fraumeni syndrome (LFS), a hereditary cancer predisposition disorder characterized by early-onset cancers. The population prevalence of P/LP germline TP53 variants is estimated to be approximately one in every 3,500 to 20,000 individuals. However, these estimates are likely impacted by ascertainment biases and lack of clinical and genetic data to account for potential confounding factors, such as clonal hematopoiesis. Genome-first approaches of cohorts linked to phenotype data can further refine these estimates by identifying individuals with variants of interest and then assessing their phenotypes. This study evaluated P/LP germline (variant allele fraction ≥30%) TP53 variants in three cohorts: UK Biobank (UKB, n = 200,590), Geisinger (n = 170,503), and Penn Medicine Biobank (PMBB, n = 43,731). A total of 109 individuals were identified with P/LP germline TP53 variants across the three databases. The TP53 p.R181H variant was the most frequently identified (9 of 109 individuals, 8%). A total of 110 cancers, including 47 hematologic cancers (47 of 110, 43%), were reported in 71 individuals. The prevalence of P/LP germline TP53 variants was conservatively estimated as 1:10,439 in UKB, 1:3,790 in Geisinger, and 1:2,983 in PMBB. These estimates were calculated after excluding related individuals and accounting for the potential impact of clonal hematopoiesis by excluding heterozygotes who ever developed a hematologic cancer. These varying estimates likely reflect intrinsic selection biases of each database, such as healthcare or population-based contexts. Prospective studies of diverse, young cohorts are required to better understand the population prevalence of germline TP53 variants and their associated cancer penetrance.

Multiple TP53 p.R337H haplotypes and implications for tumor susceptibility.

The germline TP53 p.R337H mutation is reported as the most common germline TP53 variant. It exists at a remarkably high frequency in the population of southeast Brazil as founder mutation in two distinct haplotypes with the most frequent co-segregating with the p.E134∗ variant of the XAF1 tumor suppressor and an increased cancer risk. Founder mutations demonstrate linkage disequilibrium with neighboring genetic polymorphic markers that can be used to identify the founder variant in different geographic regions and diverse populations. We report here a shared haplotype among Brazilian, Portuguese, and Spanish families and the existence of three additional distinct TP53 p.R337H alleles. Mitochondrial DNA sequencing and Y-STR profiling of Brazilian carriers of the founder TP53 p.R337H allele reveal an excess of Native American haplogroups in maternal lineages and exclusively European haplogroups in paternal lineages, consistent with communities established through male European settlers with extensive intermarriage with Indigenous women. The identification of founder and independent TP53 p.R337H alleles underlines the importance for considering the haplotype as a functional unit and the additive effects of constitutive polymorphisms and associated variants in modifier genes that can influence the cancer phenotype.