Unclassified Variants of BRCA1 and BRCA2 in Korean Patients With Ovarian Cancer

BRCA1/2 variants of unknown significance in hereditary breast and ovarian cancer (HBOC) syndrome: looking for the hidden meaning

Hereditary breast and ovarian cancer syndrome is caused by germline mutations in BRCA1/2 genes. These genes are very large and their mutations are heterogeneous and scattered throughout the coding sequence. In addition to the above-mentioned mutations, variants of uncertain/unknown significance (VUSs) have been identified in BRCA genes, which make more difficult the clinical management of the patient and risk assessment. In the last decades, several laboratories have developed different databases that contain more than 2000 variants for the two genes and integrated strategies which include multifactorial prediction models based on direct and indirect genetic evidence, to classify the VUS and attribute them a clinical significance associated with a deleterious, high-low or neutral risk. This review provides a comprehensive overview of literature studies concerning the VUSs, in order to assess their impact on the population and provide new insight for the appropriate patient management in clinical practice.

Awareness of genetic counseling and genetic testing for hereditary gynecologic cancers among Korean healthcare providers: A survey

We conducted a survey to evaluate the awareness of genetic counseling and testing for hereditary gynecologic cancers among Korean healthcare providers. We performed an on-the-spot survey using 29 questions on respondents' basic information, awareness of pre/post-test genetic counseling, genetic information management, and related social issues. We surveyed healthcare providers who attended the 2019 Hereditary Gynecologic Cancer Symposium organized by the Korean Society of Gynecologic Oncology. Of the 108 attendees, 85 (78.7%) participated in the survey. Among them, 45% (37/83) and 40% (33/83) did not have a separate clinic and had a dedicated team for genetic counseling in their institutions, respectively. Most respondents (60/76, 79%) recommended genetic testing for all women diagnosed with epithelial ovarian cancer. Many respondents simultaneously (20/85, 24%) or sequentially (45/85, 53%) tested for both pathogenic somatic and germline variants, whereas a few respondents (2/85, 2%) checked for only pathogenic somatic variants using tissue samples. Only 20% (17/85) of the respondents recommended genetic testing for all women with endometrial cancer; meanwhile, 68% (58/86) offered the test based on the results of the screening test or family history. Risk-reducing salpingo-oophorectomy was recommended to unaffected women with pathogenic BRCA1/2 variants by 69.4% of the respondents (59/85). Most respondents (73/85, 85.9%) needed a manual on bioethics law; a few required a clinical update of hereditary cancer (73/85, 85.9%). The awareness of genetic counseling and testing and the pattern of clinical practice for hereditary gynecologic cancers differ among institutions and regions in Korea. A discussion on these issues and the development of an integrated manual for healthcare providers are required.

Reclassification of BRCA1 and BRCA2 variants found in ovarian epithelial, fallopian tube, and primary peritoneal cancers

Objective

We investigated the proportions of and reclassified BRCA1/2 variants of unknown significance (VUS) in Korean patients with epithelial ovarian, tubal, and primary peritoneal cancers.

Methods

Data from 805 patients who underwent genetic testing for BRCA1/2 from January 1, 2006 to August 31, 2018 were included. The VUS in BRCA1/2 were reclassified using the 2015 American College of Medical Genetics and Genomics and the Association for Molecular Pathology standards and guidelines.

Results

A BRCA1 pathogenic variant was found in 17.0% (137/805) of the patients, and BRCA1 VUS were found in 15.9% (128/805) of the patients. Further, 8.7% (69/805) of the patients possessed a BRCA2 pathogenic variant and 18.4% (148/805) of the patients possessed BRCA2 VUS. Fifty-three specific BRCA1 VUS were found and 20 were further reclassified as benign (n=11), likely benign (n=5), likely pathogenic (n=3), and pathogenic (n=1). The remaining 33 remained classified as VUS. For BRCA2, 55 specific VUS were detected; among these, 14 were reclassified as benign or likely benign, and 2 were reclassified as likely pathogenic. Among the 805 patients, 195 were found to have only VUS and no pathogenic variants (PV), and 41.5% (81/195) were reclassified as benign or likely benign, and 10.3% (20/195) as pathogenic or likely pathogenic variants.

Conclusions

Approximately 33.3% (36/108) of the specific BRCA1/2 variants analyzed in this study that were initially classified as VUS over a 13-year period were reclassified. Among these, 5.6% (6/108) were reclassified as pathogenic or likely pathogenic variants.

Identification of novel mutations of ovarian cancer-related genes from RNA-sequencing data for Japanese epithelial ovarian cancer patients

Ovarian cancer has the highest mortality rate among gynecological cancers. Gene mutations are involved in the carcinogenesis, metastasis, and therapeutic response in ovarian cancer. However, the variety and proportion of gene mutation is not fully analyzed in Japanese ovarian cancer patients, especially, in those with recurrent tumors. In the present study, RNA-sequencing was performed for 32 clinical ovarian specimens obtained from 24 Japanese patients (24 primary cancer specimens and 8 recurrent specimens paired with corresponding primary cancer specimens). Mutations in 24 primary specimens were analyzed by comparing the sequence data mapped on RefSeq genes with those in the public online databases BRCA Exchange, COSMIC, ClinVar, and cBioportal. Mutations were observed in TP53 in 16 specimens (67%), BRCA1 in 9 (38%), BRCA2 in 13 (54%), ARID1A in 3 (13%), PIK3CA in 2 (8%), KRAS in 1 (4%), PTEN in 1 (4%), and CTNNB1 in 1 (4%), excluding synonymous mutations. Among those identified muations, 13 of 14 mutations in TP53, 10 of 11 mutations of BRCA1, 10 of 23 mutation positions of BRCA2, none of 7 mutations of ARID1A, 1 mutation of PIK3CA, and 1 mutation of CTNNB1 were consistent with those reported in the public online databases; however, the other mutations identified were novel. Comparison between matched-paired specimens of primary and recurrent tumors revealed the changes of mutational status in expressed RNAs. RNA-sequencing-based mutation analysis will be useful to reveal ethnic differences of gene mutations in ovarian cancer and to understand the contribution of gene mutations to recurrence.

Clinicopathological Features of Patients with the BRCA1 c.5339T>C (p.Leu1780Pro) Variant

PURPOSE

Recent studies revealed the BRCA1 c.5339T>C, p.Leu1780Pro variant (L1780P) is highly suggested as a likely pathogenic. The aim of this study was to evaluate clinicopathologic features of L1780P with breast cancer (BC) using multicenter data from Korea to reinforce the evidence as a pathogenic mutation and to compare L1780P and other BRCA1/2mutations using Korean Hereditary Breast Cancer (KOHBRA) study data.

Materials and Methods

The data of 54 BC patients with L1780P variant from 10 institutions were collected and the clinicopathologic characteristics of the patients were reviewed. The hereditary breast and/or ovarian cancer-related characteristics of the L1780P variant were compared to those of BC patients in the KOHBRA study.

RESULTS

The median age of all patients was 38 years, and 75.9% of cases showed triple-negative breast cancer. Comparison of cases with L1780P to carriers from the KOHBRA study revealed that the L1780P patients group was more likely to have family history (FHx) of ovarian cancer (OC) (24.1% vs. 19.6% vs. 11.2%, p < 0.001 and p=0.001) and a personal history of OC (16.7% vs. 2.9% vs. 1.3%, p=0.003 and p=0.001) without significant difference in FHx of BC and bilateral BC. The cumulative risk of contralateral BC at 10 years after diagnosis was 31.9%, while the cumulative risk of OC at 50 years of age was 20.0%. Patients with L1780P showed similar features with BRCA1 carriers and showed higher penetrance of OC than patients with other BRCA1 mutations.

CONCLUSION

L1780P should be considered as a pathogenic mutation. Risk-reducing salpingo-oophorectomy is highly recommended for women with L1780P.

Prevalence of germline BRCA mutations among women with carcinoma of the peritoneum or fallopian tube

Objective

The aim of the present study was to assess the frequency of germline mutations in patients with peritoneal carcinoma (PC) or the fallopian tube carcinoma (FTC), using a multi-gene panel.

Methods

Twenty-six patients diagnosed with either PC or FTC between January 2013 and December 2016 were recruited consecutively. Germline DNA was sequenced using a 6-gene next generation sequencing (NGS) panel following genetic counseling. Surgico-medical information was obtained from hospital records. Genetic variations were detected using the panel and were cross-validated by Sanger direct sequencing.

Results

Germline BRCA1/2 mutations were identified in 6 patients (23.1%). Four were detected in patients with PC and 2 were in FTC patients. No mutations were detected in TP53, PTEN, CDH1, or PALB2. We identified 11 variant of uncertain significance (VUS) in 9 patients; 2 in BRCA1, 3 in BRCA2, 2 in TP53, and 4 in CDH1. We also detected a CDH1 c.2164+16->A VUS in 3 patients.

Conclusion

The prevalence of germline BRCA1/2 mutations in patients with PC or FTC is comparable to that of BRCA1/2 mutations in epithelial ovarian cancer patients.