High-risk pathogenic germline variants in blood relatives of BRCA1/2 negative probands.

BACKGROUND: Tailored, preventive cancer care requires the identification of pathogenic germline variants (PGVs) among potentially at-risk blood relatives (BRs). Cascade testing is carried out for BRs of probands who are positive for PGVs of an inherited cancer but not for negative probands. This study was conducted to examine the prevalence of PGVs for BRs of PGV-negative probands. METHODS: PGV prevalence was assessed for 682 BRs of 281 probands with BRCA1/BRCA2 wild-type hereditary breast and ovarian cancer (HBOC) syndrome. RESULTS: PGVs were discovered in 22 (45.8%) of the 48 BRs of the PGV-positive probands and in 14 (2.2%) of 634 BRs of the PGV-negative probands. Eleven PGVs on high-risk BRCA1, BRCA2, and TP53 genes were present only in BRs and not in the probands (probands vs BRs in Fisher exact test; p = 0.0104; odds ratio [OR] = 0.000 [0.000-0.5489 of 95% confidence interval]), partly due to the nature of the selection criteria. The enrichment of high-risk PGVs among BRs was also significant as compared with a non-cancer East Asian population (p = 0.0016; OR = 3.0791 [1.5521-5.6694]). PGV prevalence, risk class of gene, and genotype concordance were unaffected by the cancer history among BRs. CONCLUSION: These findings imply the necessity to construct a novel testing scheme to complement cascade testing.

Case series of Li-Fraumeni syndrome: carcinogenic mechanisms in breast cancer with TP53 pathogenic variant carriers.

BACKGROUND: Li-Fraumeni syndrome (LFS), a hereditary condition attributed to TP53 pathogenic variants,(PV), is associated with high risks for various malignant tumors, including breast cancer. Notably, individuals harboring TP53 PVs are more likely (67-83%) to develop HER2 + breast cancer than noncarriers (16-25%). In this retrospective study, we evaluated the associations between TP53 variants and breast cancer phenotype. METHODS: We conducted a retrospective review of the medical records of patients with LFS treated at a single institution and reviewed the literature on TP53 functions and the mechanisms underlying HER2 + breast cancer development in LFS. RESULTS: We analyzed data for 10 patients with LFS from 8 families. The median age at the onset of the first tumor was 35.5 years. Only case 2 met the classic criteria; this patient harbored a nonsense variant, whereas the other patients carried missense variants. We observed that 9 of 10 patients developed breast cancer. Immunohistochemical analyses revealed that 40% of breast cancers in patients with LFS were HR - /HER2 + . The median age at the onset of breast cancer was slightly younger in HR - /HER2 + tumors than in HR + /HER2 - tumors (31 years and 35.5 years, respectively). CONCLUSIONS: The occurrence of HER2 + breast cancer subtype was 40% in our LFS case series, which is greater than that in the general population (16-25%). Some TP53 PVs may facilitate HER2-derived oncogenesis in breast cancer. However, further studies with larger sample sizes are warranted to clarify the oncogenic mechanisms underlying each subtype of breast cancer in TP53 PV carriers.

Risk-reducing decisions regarding germline BRCA pathogenic variant: focusing on the timing of genetic testing and RRSO.

BACKGROUND: In Japan, the public insurance policy was revised in 2020 to cover hereditary breast and ovarian cancer (HBOC), including genetic testing and surveillance, for patients with breast cancer (BC). Consequently, the demand for risk-reducing salpingo-oophorectomy (RRSO) has increased. This study aimed to clarify the changes in the demand and timing of genetic testing and RRSO associated with public insurance coverage for HBOC in Japan. METHODS: This retrospective analysis included 350 women with germline BRCA (gBRCA) pathogenic variants (PVs) who had visited gynaecologists; they received gBRCA genetic testing at 45.1±10.6 (20-74) years. The use of medical testing and preventive treatment was compared between the preinsurance and postinsurance groups using Mann-Whitney U and Fisher's exact tests. RESULTS: The findings indicate that RRSO rates doubled from 31.4% to 62.6% among patients with gBRCA-PV. The implementation rate was 32.4% among unaffected carriers and 70.3% among BC-affected patients. Younger patients received genetic testing with significantly shorter intervals between BC diagnosis and genetic testing and between genetic testing and RRSO. CONCLUSION: Overall, the insurance coverage for HBOC patients with BC has increased the frequency of RRSO in Japan. However, a comparison between the number of probands and family members indicated that the diagnosis among family members is inadequate. The inequality in the use of genetic services by socioeconomic groups is an issue of further concern.

Impact of the coverage of risk-reducing salpingo-oophorectomy by the national insurance system for women with BRCA pathogenic variants in Japan.

To determine the impact of the coverage of risk-reducing salpingo-oophorectomy (RRSO) and mastectomy (RRM) as well as genetic testing for BRCA pathogenic variants by the national insurance system in Japan. We compared the clinical background of women who underwent RRSO at our institution before and after its coverage by the national insurance system. Those who underwent RRSO between January 2017 and December 2019 and between April 2020 and March 2022 were classified as Period. A and B, respectively. Overall, 134 women underwent RRSO during the study period. In Period A and B, 45 and 89 women underwent RRSO for the study period was 36 and 24 months, respectively. Compared with Period A, the number of women who underwent RRSO per month increased by threefold in Period B (p < 0.01). In addition, the number of women who underwent surgery for breast cancer along with RRSO increased in Period B (p < 0.01). Although the number of women who underwent concurrent RRM with RRSO in Period B increased, the difference was not statistically significant. Compared with Period A, the number of women diagnosed with BRCA pathogenic variant increased by 3.9-fold, and the proportion of women who underwent concurrent hysterectomy at the time of RRSO decreased from 66 to 7.9% in Period B (p < 0.01). Owing to the introduction of the national insurance system, the number of women who underwent RRSO and concurrent surgery for breast cancer at the time of RRSO increased in Japan.

Detection of BRCA1 Pathogenic Variant in a 24-Year-Old Endometrial Cancer Patient: Risks of Several Hereditary Tumor Syndromes Assessed Using Germline Multigene Panel Testing.

A 24-year-old woman suspected of Lynch syndrome was found to carry a BRCA1 pathogenic variant, based on germline multigene panel testing (MGPT). The patient was diagnosed with endometrial carcinoma and underwent modified radical hysterectomy, bilateral salpingo-oophorectomy, pelvic lymphadenectomy, and omentectomy at the age of 23. Based on her father's history of colorectal cancer and her history of early onset endometrial cancer, mismatch repair protein immunohistochemistry analysis was performed. However, no loss of expression for mismatch repair proteins was found. Given her family history of ovarian and breast cancers, MGPT was recommended to identify the presence of any hereditary tumor syndromes. This testing revealed a BRCA1 pathogenic variant (exon13: c.1016delA, p.Lys339ArgfsX2) and diagnosed as hereditary breast and ovarian cancer syndrome (HBOC). Subsequently, the patient's mother also underwent single-site analysis for this variant, and the same pathogenic variant was detected. The patient and her mother are at high risk of developing BRCA1-associated HBOC-related cancers. Based on family history, clinical surveillance is currently underway for this patient and her mother. Currently, MGPT offers the potential for comprehensive genetic cancer risk assessment and may provide a more rational approach for the genetic assessment of those individuals whose personal and family cancer histories do not fit neatly into a single syndrome. This case suggests that if a patient is at high risk for hereditary tumor syndromes, MGPT should be considered to improve disease management strategies in clinical settings.

Prevalence of disease-causing genes in Japanese patients with BRCA1/2-wildtype hereditary breast and ovarian cancer syndrome.

Panel sequencing of susceptibility genes for hereditary breast and ovarian cancer (HBOC) syndrome has uncovered numerous germline variants; however, their pathogenic relevance and ethnic diversity remain unclear. Here, we examined the prevalence of germline variants among 568 Japanese patients with BRCA1/2-wildtype HBOC syndrome and a strong family history. Pathogenic or likely pathogenic variants were identified on 12 causal genes for 37 cases (6.5%), with recurrence for 4 SNVs/indels and 1 CNV. Comparisons with non-cancer east-Asian populations and European familial breast cancer cohorts revealed significant enrichment of PALB2, BARD1, and BLM mutations. Younger onset was associated with but not predictive of these mutations. Significant somatic loss-of-function alterations were confirmed on the wildtype alleles of genes with germline mutations, including PALB2 additional somatic truncations. This study highlights Japanese-associated germline mutations among patients with BRCA1/2 wildtype HBOC syndrome and a strong family history, and provides evidence for the medical care of this high-risk population.

Lynch syndrome-associated endometrial carcinoma with MLH1 germline mutation and MLH1 promoter hypermethylation: a case report and literature review.

BACKGROUND: Lynch syndrome is an autosomal dominant inherited disease caused by germline mutations in mismatch repair genes. Analysis for microsatellite instability (MSI) and immunohistochemistry (IHC) of protein expressions of disease-associated genes is used to screen for Lynch syndrome in endometrial cancer patients. When losses of both MLH1 and PMS2 proteins are observed by IHC, MLH1 promoter methylation analysis is conducted to distinguish Lynch syndrome-associated endometrial cancer from sporadic cancer. CASE PRESENTATION: Here we report a woman who developed endometrial cancer at the age of 49 years. She had a family history of colorectal cancer (first-degree relative aged 52 years) and stomach cancer (second-degree relative with the age of onset unknown). No other family history was present, and she failed to meet the Amsterdam II criteria for the diagnosis of Lynch syndrome. Losses of MLH1 and PMS2, but not MSH2 and MSH6, proteins were observed by IHC in endometrial cancer tissues. Because MLH1 promoter hypermethylation was detected in endometrial cancer tissue samples, the epigenetic silencing of MLH1 was suspected as the cause of the protein loss. However, because of the early onset of endometrial cancer and the positive family history, a diagnosis of Lynch syndrome was also suspected. Therefore, we provided her with genetic counseling. After obtaining her consent, MLH1 promoter methylation testing and genetic testing of peripheral blood were performed. MLH1 promoter methylation was not observed in peripheral blood. However, genetic testing revealed a large deletion of exon 5 in MLH1; thus, we diagnosed the presence of Lynch syndrome. CONCLUSIONS: Both MLH1 germline mutation and MLH1 promoter hypermethylation may be observed in endometrial cancer. Therefore, even if MLH1 promoter hypermethylation is detected, a diagnosis of Lynch syndrome cannot be excluded.

[Genetic counseling and practice of hereditary cancers at Shikoku Cancer Center].

Although the progress in understanding human genetics regarding cancer has been applied to the medical practice of treating hereditary cancers in developed western countries, it is not widely implemented in Japan. We started treating hereditary cancers at NHO Shikoku Cancer Center in November 2000. Our institution has a multidisciplinary team that provides medical care and genetic counseling for patients with hereditary cancers, and their relatives. The team consists of doctors from several related departments, and paramedics including a genetic counselor who participated as of 2009. Medical care of patients with hereditary cancers should not be separated from general oncological practice, but incorporate all medical professionals, including doctors of related departments and paramedic. We have attempted to identify patients with hereditary cancer and their family members and relatives at high risk; we followed them up and provided risk-reducing therapies for them at our cancer center. Here we present the framework of our practice in treating hereditary cancers. We discuss appropriate goals and future perspectives in the field of hereditary cancer in Japan.