Prevalence of Recurrent Mutations Predisposing to Breast Cancer in Early-Onset Breast Cancer Patients from Poland

Spectrum and characteristics of germline PALB2 pathogenic variants in 1556 early-onset breast cancer patients in China

PURPOSE

Limited data are available regarding the partner and localizer of BRCA2 (PALB2) in Chinese patients with early breast cancer. This study aimed to assess the spectrum and characteristics of germline PALB2 pathogenic variants in this population.

METHODS

Peripheral blood samples were collected from 1556 patients diagnosed with BRCA1/2-negative early-onset breast cancer. All coding regions and exon‒intron boundaries of the PALB2 genes were screened through next-generation sequencing.

RESULTS

The prevalence of PALB2 pathogenic variants was approximately 0.77% in the cohort. Eleven PALB2 pathogenic variants were identified in twelve participants, including five frameshift mutations and six nonsense mutations. All other variants were detected once, except for PALB2 c.1056_1057del (detected twice). Two PALB2 carriers (2/12, 16.7%) have documented family history of breast cancer and/or ovarian cancer. Patients with a positive family history exhibited a threefold higher possibility of being identified as PALB2 carriers than those without a family history (2% vs. 0.69%), although the difference was not statistically significant (p = 0.178). Compared to non-carriers, PALB2 carriers has a tendency to appear in younger age (≤ 30 years) (25% vs 14.4%), human epidermal growth factor receptor-2 (HER2)-negative status (83.3% vs. 70.2%), and diagnosed with invasive micropapillary carcinoma (16.7% vs 3.1%).

CONCLUSION

The prevalence of the germline PALB2 pathogenic variants was approximately 0.77% in Chinese patients with BRCA1/2-negative early-onset breast cancer. Our findings is crucial for understanding population-specific genetic risks and offering insights that can enhance genetic counseling and genetic testing strategies in this population.

Landscape of germline BRCA1/BRCA2 variants in breast and ovarian cancer in Peru

Background

There is an increasing amount of data from Latin America on the characterization of BRCA variants; however, there is limited information from Peru. We conducted a retrospective study to describe germline pathogenic/likely pathogenic(P/LP) variants and variants of uncertain/unknown significance (VUS) in the BRCA1 and BRCA2 genes in Peru, in patients with breast and ovarian cancer, candidates for treatment with poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors.

Methods

The patients were evaluated during the period 2019-2021. Genomic DNA was isolated from peripheral blood samples and targeted sequencing was performed using the Ampliseq BRCA panel. Genetic variant interpretation was carried out in accordance with the recommendations of the American College of Medical Genetics and ClinVar. During this period, 525 patients (143 with breast cancer and 382 with ovarian cancer) were studied.

Results

We found that 14.7% (21/143) of breast cancer patients and 20.7% (79/382) of ovarian cancer patients were carriers of P/LP variants in BRCA1/2. The most frequent pathogenic variants detected in BRCA1 were c.2105dupT (BIC: 2224insT, n=12, 18.75%), c.68_69delAG (BIC: 185delAG, n=6, 9.38%), c.140G>T and c.815_824dupAGCCATGTGG (n=5, 7.81%), while in BRCA2 were c.8023A>G (n=6, 16.67%), c.6024dupG (BIC: 6252insG, n=4, 11.11%), and c.9235delG (BIC: 9463delG, n=3, 8.33%). Regarding VUS, we found that 6.99% (10/143) of breast cancer patients and 7.33% (28/382) of ovarian cancer patients were carriers of a VUS in BRCA1/2. For BRCA1, the most frequent VUS was c.93C>G (n=2), and for BRCA2, c.5465A>T (n=4), c.3101T>C (n=3), c.205C>A and c.437T>C (n=2).

Conclusion

We found a frequency of 14.7% germline mutations in breast cancer patients and 20.7% in ovarian cancer patients. The most recurrent mutations were BRCA1 c.2105dupT and BRCA2 c.8023A>G. We found that BRCA2 c.8023A>G, c.6024dupG, and c.9235delG were not previously reported in Peruvian patients. BRCA1 c.2344dupA is a novel mutation that has not been previously reported in any database. The frequency of VUS in our cohort was 7.2%.

The CHK2 kinase is recurrently mutated and functionally impaired in the germline of pediatric cancer patients

Predisposing CHEK2 germline variants are associated with various adult-type malignancies, whereas their impact on cancer susceptibility in childhood cancer is unclear. To understand the frequency of germline variants in the CHEK2 gene and their impact on pediatric malignancies, we used whole-exome sequencing to search for CHEK2 variants in the germlines of 418 children diagnosed with cancer in our clinics. Moreover, we performed functional analysis of the pathogenic CHEK2 variants to analyze the effect of the alterations on CHK2 protein function. We detected a CHEK2 germline variant in 32/418 (7.7%) pediatric cancer patients and 46.8% of them had leukemia. Functional analysis of the pathogenic variants revealed that 5 pathogenic variants impaired CHK2 protein function. 6/32 patients carried one of these clearly damaging CHEK2 variants and two of them harbored a matching family history of cancer. In conclusion, we detected germline CHEK2 variants in 7.7% of all pediatric cancer patients, of which a minority but still relevant fraction of approximately 20% had a profound impact on protein expression or its phosphorylation after irradiation-induced DNA damage. Accordingly, we conclude that CHEK2 variants increase the risk for not only adult-onset but also pediatric cancer.

Importance of Germline and Somatic Alterations in Human MRE11, RAD50, and NBN Genes Coding for MRN Complex

The MRE11, RAD50, and NBN genes encode for the nuclear MRN protein complex, which senses the DNA double strand breaks and initiates the DNA repair. The MRN complex also participates in the activation of ATM kinase, which coordinates DNA repair with the p53-dependent cell cycle checkpoint arrest. Carriers of homozygous germline pathogenic variants in the MRN complex genes or compound heterozygotes develop phenotypically distinct rare autosomal recessive syndromes characterized by chromosomal instability and neurological symptoms. Heterozygous germline alterations in the MRN complex genes have been associated with a poorly-specified predisposition to various cancer types. Somatic alterations in the MRN complex genes may represent valuable predictive and prognostic biomarkers in cancer patients. MRN complex genes have been targeted in several next-generation sequencing panels for cancer and neurological disorders, but interpretation of the identified alterations is challenging due to the complexity of MRN complex function in the DNA damage response. In this review, we outline the structural characteristics of the MRE11, RAD50 and NBN proteins, the assembly and functions of the MRN complex from the perspective of clinical interpretation of germline and somatic alterations in the MRE11, RAD50 and NBN genes.

Family History of Cancer is associated with poorer prognosis in Oral Squamous Cell Carcinoma

OBJECTIVE

The purpose of this study was to investigate the prognostic value of the family history of cancer (FHC) in predicting survival and clinicopathological features in oral squamous cell carcinoma (OSCC) patients.

MATERIALS AND METHODS

This single-institution study utilized data from 610 patients undergoing surgery from 2014 to 2020 that was prospectively collected and cataloged for research purposes. All patients underwent standard surgery with/without radiotherapy or chemoradiotherapy. We statistically evaluated whether FHC was associated with changes in disease-free survival (DFS) and disease-specific survival (DSS).

RESULTS

Among 610 patients, 141 (23.1%) reported a family history of cancer. The distribution of clinicopathological characteristics was balanced between FHC-positive and FHC-negative OSCC patients. FHC-positive patients had decreased DFS (P=0.005) and DSS (P=0.018) compared to FHC-negative patients.

CONCLUSIONS

FHC-positive OSCC patients have a poorer prognosis. FHC positivity is an independent predictor of negative outcomes based on DFS and DSS. FHC should be a consideration in screening, evaluating, counseling, and treating OSCC patients.

Cancer Predisposition Genes in Adolescents and Young Adults (AYAs): a Review Paper from the Italian AYA Working Group

PURPOSE OF REVIEW

The present narrative systematic review summarizes current knowledge on germline gene mutations predisposing to solid tumors in adolescents and young adults (AYAs).

RECENT FINDINGS

AYAs with cancer represent a particular group of patients with specific challenging characteristics and yet unmet needs. A significant percentage of AYA patients carry pathogenic or likely pathogenic variants (PV/LPVs) in cancer predisposition genes. Nevertheless, knowledge on spectrum, frequency, and clinical implications of germline variants in AYAs with solid tumors is limited. The identification of PV/LPV in AYA is especially critical given the need for appropriate communicative strategies, risk of second primary cancers, need for personalized long-term surveillance, potential reproductive implications, and cascade testing of at-risk family members. Moreover, these gene alterations may potentially provide novel biomarkers and therapeutic targets that are lacking in AYA patients. Among young adults with early-onset phenotypes of malignancies typically presenting at later ages, the increased prevalence of germline PV/LPVs supports a role for genetic counseling and testing irrespective of tumor type.

Association of recurrent mutations in BRCA1, BRCA2, RAD51C, PALB2, and CHEK2 with the risk of borderline ovarian tumor

Background

There are several genes associated with ovarian cancer risk. Molecular changes in borderline ovarian tumor (BOT) indicate linkage of this disease to type I ovarian tumors (low-grade ovarian carcinomas). This study determined the prevalence and association of mutations in BRCA1, BRCA2, PALB2, RAD51C, and CHEK2 with the risk of BOTs.

Methods

The study group consisted of 102 patients with histologically confirmed BOT and 1743 healthy controls. In addition, 167 cases with ovarian cancer G1 were analyzed. The analyses included genotyping of 21 founder and recurrent mutations localized in 5 genes (BRCA1, BRCA2, PALB2, RAD51C, and CHEK2). The risk for developing BOT and low-grade ovarian cancer, as well as the association of tested mutations with survival, was estimated.

Results

The CHEK2 missense mutation (c.470T>C) was associated with 2-times increased risk of BOT (OR=2.05, p=0.03), at an earlier age at diagnosis and about 10% worse rate of a 10-year survival. Mutations in BRCA1 and PALB2 were associated with a high risk of ovarian cancer G1 (OR=8.53, p=0.005 and OR=7.03, p=0.03, respectively) and were related to worse all-cause survival for BRCA1 carriers (HR=4.73, 95%CI 1.45–15.43, p=0.01).

Conclusions

Results suggest that CHEK2 (c.470T>C) may possibly play a role in the pathogenesis of BOT, but due to the low number of BOT patients, obtained results should be considered as preliminary. Larger more in-depth studies are required.

Genetic predisposition to male breast cancer in Poland

BACKGROUND

Breast cancer in men accounts for fewer than 1 % of all breast cancer cases diagnosed in men and women. Genes which predispose to male breast cancer include BRCA1 and BRCA2. The role of other genes is less clear. In Poland, 20 founder mutations in BRCA1, BRCA2, CHEK2, PALB2, NBN, RECQL are responsible for the majority of hereditary breast cancer cases in women, but the utility this genes panel has not been tested in men.

METHODS

We estimated the prevalence of 20 alleles in six genes (BRCA1, BRCA2, CHEK2, PALB2, NBN, RECQL) in 165 Polish male breast cancer patients. We compared the frequency of selected variants in male breast cancer cases and controls.

RESULTS

One of the 20 mutations was seen in 22 of 165 cases (13.3%). Only one BRCA1 mutation and two BRCA2 mutations were found. We observed statistically significant associations for PALB2 and CHEK2 truncating mutations. A PALB2 mutation was detected in four cases (OR = 11.66; p < 0.001). A CHEK2 truncating mutation was detected in five cases (OR = 2.93;p = 0.02).

CONCLUSION

In conclusion, we recommend that a molecular test for BRCA1, BRCA2, PALB2 and CHEK2 recurrent mutations should be offered to male breast cancer patients in Poland.

The Unique Biology behind the Early Onset of Breast Cancer

Breast cancer commonly affects women of older age; however, in developing countries, up to 20% of breast cancer cases present in young women (younger than 40 years as defined by oncology literature). Breast cancer in young women is often defined to be aggressive in nature, usually of high histological grade at the time of diagnosis and negative for endocrine receptors with poor overall survival rate. Several researchers have attributed this aggressive nature to a hidden unique biology. However, findings in this aspect remain controversial. Thus, in this article, we aimed to review published work addressing somatic mutations, chromosome copy number variants, single nucleotide polymorphisms, differential gene expression, microRNAs and gene methylation profile of early-onset breast cancer, as well as its altered pathways resulting from those aberrations. Distinct biology behind early-onset of breast cancer was clear among estrogen receptor-positive and sporadic cases. However, further research is needed to determine and validate specific novel markers, which may help in customizing therapy for this group of patients.

CHEK2 Germline Variants in Cancer Predisposition: Stalemate Rather than Checkmate

Germline alterations in many genes coding for proteins regulating DNA repair and DNA damage response (DDR) to DNA double-strand breaks (DDSB) have been recognized as pathogenic factors in hereditary cancer predisposition. The ATM-CHEK2-p53 axis has been documented as a backbone for DDR and hypothesized as a barrier against cancer initiation. However, although CHK2 kinase coded by the CHEK2 gene expedites the DDR signal, its function in activation of p53-dependent cell cycle arrest is dispensable. CHEK2 mutations rank among the most frequent germline alterations revealed by germline genetic testing for various hereditary cancer predispositions, but their interpretation is not trivial. From the perspective of interpretation of germline CHEK2 variants, we review the current knowledge related to the structure of the CHEK2 gene, the function of CHK2 kinase, and the clinical significance of CHEK2 germline mutations in patients with hereditary breast, prostate, kidney, thyroid, and colon cancers.