The hereditary breast and ovarian cancer (HBOC) registration system of Japan was established by the Japanese HBOC Consortium. The first trial was registered in 2015 in four institutions to which some registration committee members belonged. We analyzed the information of 830 Japanese pedigrees, who underwent BRCA1/2 genetic testing, including mutation carriers with BRCA1 (N = 127) and BRCA2 (N = 115), and their families. The mutation-positive rate was 19.7%. Variants of uncertain significance were found in 6.5% of all individuals subjected to genetic testing for BRCA1/2. Compared to the United States, Japan had a higher mutation-positive rate in most categories, except for the groups with male breast cancer. Among the intrinsic subtypes of BRCA1-associated breast cancers, 75.8% were triple-negative. The incidence rate of contralateral breast cancer in BRCA1/2 mutation carriers was 0.99%/year. Among 240 mutation carriers, 26 and 62 patients underwent risk-reducing mastectomy (RRM) and risk-reducing salpingo-oophorectomy (RRSO), respectively; the respective frequencies of occult cancer were 7.1 and 3.2%. Metachronous breast cancer after RRM or peritoneal cancer after RRSO was not observed during the follow-up period. The nationwide registration system began last year and the system enables followup analysis in Japan.

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.

PurposeProphylactic surgery is a preemptive strategy for hereditary breast and ovarian cancer (HBOC). Prophylactic mastectomy (PM) reduces breast cancer risk by > 90%. The aim of our study is to analyze the information of the Japanese pedigrees and to utilize the results for clinical practice.MethodsWe statistically analyzed records of HBOC registrees who had undergone BRCA1/2 genetic testing at seven medical institutions up until 2016. In the cases of PM, we examined breasts with the use of mammography (MMG), ultrasound (US), and magnetic resonance imaging (MRI) before surgery. After PM, the specimens were divided about 1 cm serially and examined in their entirety.ResultsOf 1527 registrees who underwent BRCA testing, 1125 (73.7%) were negative for BRCA1/2 mutation, 297 (19.5%) were positive for BRCA1/2 mutation (BRCA1/2MUT+), and 105 (6.9%) had uncertain results. To decide whether to undergo total mastectomy vs. breast-conserving surgery (BCS), 370 registrees underwent presurgical genetic testing. During the follow-up period, four new-onset breast cancers were found among the 55 non-affected BRCA carriers. Among the 73 BRCA1/2MUT+ carriers who underwent BCS, 3 were found to have ipsilateral breast cancer. Of 189 BRCA1/2MUT+ carriers with unilateral breast cancer, 8 were found to have contralateral breast cancer. Of 53 PM specimens, 6 (11.3%) were found to have occult breast cancer despite using MMG, US, and MRI.ConclusionsOur report showed a relatively higher incidence rate of occult cancer at 11.3% in PM specimens despite thorough pre-operative radiological evaluations, which included a breast MRI. Considering the occult cancer rates and the various pathological methods of our study and published studies, we propose the necessity of a histopathological protocol.

Objective The discontinuation of dual antiplatelet therapy (DAPT) increases the risk of stent thrombosis after coronary stenting. Some patients must discontinue DAPT due to gastrointestinal (GI) tract disease; however, the type of examination that is most useful for detecting GI tract diseases has not been fully evaluated. The purpose of this study was to clarify whether the immunochemical fecal occult blood test (iFOBT) can be used to predict GI tract disease-related DAPT discontinuation following stent implantation in patients with coronary artery disease. Methods A total of 181 consecutive DAPT-naïve patients who underwent coronary stenting were divided into two groups according to the results of iFOBTs: a positive iFOBT group (n=32) and a negative iFOBT group (n=149). During the 12-month follow-up period, the DAPT discontinuation rate was lower in the negative iFOBT group than in the positive iFOBT group (3.4 vs. 18.8%, p=0.005). Kaplan-Meier event-free curves showed that the DAPT discontinuation rate in the negative iFOBT group was lower than that observed in the positive iFOBT group (log-rank test: p=0.001). Logistic and Cox regression analyses showed that a positive iFOBT result was the strongest predictor of the risk of DAPT discontinuation after coronary stenting. Conclusion A positive iFOBT result is associated with DAPT discontinuation following coronary stenting.

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