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.

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.

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.