Clinical risk management of breast, ovarian, pancreatic, and prostatic cancers for BRCA1/2 variant carriers in Japan

Genetic medicine of familial and hereditary pancreatic cancer: Recent update in the era of precision cancer medicine

In Japan, 5 years have passed since the initiation of precision cancer medicine, and recent data accumulation in familial pancreatic cancer (FPC) and hereditary pancreatic cancer is outstanding. Multigene germline panel tests (MGPTs) have revealed that 7%-18% of patients with pancreatic cancer (PC) harbor pathogenic germline variants (PGVs), almost equal to the levels of breast, ovarian, endometrial, and colorectal cancers, with a higher incidence in FPC (14%-26%). The majority of PGVs seen in PC patients are clinically actionable and associated with homologous recombination (HR) pathways (6%-10%, particularly BRCA1/2 in 5%-6%), and the clinical guidelines recommend or propose genetic testing for all PC patients. Consensus guidelines have been established for most of the hereditary syndromes associated with PC risks, and surveillances of the pancreas and other at-risk organs are recommended for PGV carriers. Hereditary breast and ovarian cancer (HBOC) is the commonest hereditary cancer syndrome that has moderately increasing life-time risks of PC (3%-7% in Western countries); however, recent Japanese research demonstrated a higher risk level (BRCA1: 16%, BRCA2: 14%). Moreover, recent evidence has suggested a risk linkage between PC and ovarian cancer in HBOC pedigrees. High scores of homologous recombination deficiency suggest biallelic dysfunction of BRCA or other HR-related genes, and the likely effectiveness of platinum agents and PARP inhibitors against PCs. Remote counseling and testing are possible option in the future genetic medicine. As PC ranks in the second commonest target of precision cancer medicine in Japan, we must treat the patients and manage their at-risk relatives efficiently.

Prevalence of cardiometabolic outcomes in women who underwent salpingo-oophorectomy to prevent hereditary breast and ovarian cancer: a meta-analysis

Risk reduction salpingo-oophorectomy (RRSO) is usually performed in women with hereditary breast and ovarian cancer (HBOC) syndrome for BRCA1 and BRCA2 gene mutation carriers, resulting in surgical menopause, which is more associated with a high risk of cardiovascular and metabolic disease than in premenopausal and natural menopausal women. This study assessed the prevalence of cardiovascular and metabolic outcomes in women who underwent salpingo-oophorectomy as a preventive measure against HBOC. This meta-analysis assessed prevalence rates for four metabolic/cardiovascular conditions: myocardial infarction, hypertension, hypercholesterolemia, and type 2 diabetes mellitus. DerSimonian and Laird random-effects models were applied to all analyses, with 95% confidence interval (CI). Heterogeneity was assessed with I². We used OpenMeta Analyst software for statistical analysis. A total of five retrospective studies and one observational study involving 1,320 patients were included. The average body mass index (BMI) was 25.97 kg/m2 and the average waist circumference was 87.94 cm. The analysis across a mean 4.94-year follow-up revealed prevalence rates for acute myocardial infarction of 1.5% (95% CI 0.3-2.7; P = 0.077; I²=56.25%), hypertension of 28% (95% CI 6.9-49.1; P < 0.001; I2 = 98.42%), hypercholesterolemia of 27.2% (95% CI 6.8-47.6; P < 0.001; I²=98.67%), and type 2 diabetes mellitus of 3.3% (95% CI 1.1-5.5; P < 0.001; I²=82.44%). Our findings suggest that there is no marked increase in cardiovascular risk among women with HBOC undergoing RRSO.

Four cancer cases with pathological germline variant RAD51D c.270_271dup

Pathological germline variants (PGVs) of RAD51D increase the risk of breast and ovarian cancer. In East Asia, c.270_271dup is the most frequently detected PGV of RAD51D; however, only a few cases have been reported in Japan. We report four cancer cases with a germline RAD51D c.270_271dup PGV. Three of them (lung cancer: 2, oral cancer: 1) were incidentally identified by whole genome sequencing in patients negative for the associated cancer histories, homologous recombination (HR) deficiency, or a second hit of RAD51D in the cancer DNA. For genetic counseling, we provided information on surveillance and cascade testing based on Western guidelines. The PGVs of moderate-risk HR-related genes are difficult to detect based on phenotype, especially in male-predominant pedigrees. The current spread of cancer genomic analysis will increase opportunities for incidental variant identification. The establishment of Japanese guidelines is expected to aid in the management of PGV carriers of moderate-risk genes.

Clinical significance of germline breast cancer susceptibility gene (gBRCA) testing and olaparib as maintenance therapy for patients with pancreatic cancer

BACKGROUND

Germline breast cancer susceptibility gene (gBRCA) mutation in patients with pancreatic cancer (PC) is not common in clinical practice. Therefore, factors that efficiently show gBRCA mutations and the real-world outcomes of olaparib maintenance therapy have not been fully established. In the present study, we clarified the indicators for the effective detection of gBRCA mutation and the efficacy and safety of olaparib as maintenance therapy.

METHODS

We retrospectively analyzed 84 patients with PC who underwent gBRCA testing (BRACAnalysis, Myriad Genetics, Salt Lake City, UT, USA) at our institute between January 2021 and March 2022. For each patient, clinical data were extracted from medical records.

RESULTS

The median patient age was 64 y (29-85 y), and 41 patients (48.8%) were male. The gBRCA mutations were identified in 10 (11.9%) patients; two patients had BRCA1 mutation and eight had BRCA2 mutation. All patients with gBRCA mutation had a family history of any cancer, and eight of them had a family history of Hereditary Breast and Ovarian Cancer syndrome (HBOC)-related cancer. The gBRCA mutation rate was higher for patients with PC with a family history of HBOC-related cancer compared to that in patients with PC having a family history of other cancers and no family history of cancer (22.9% vs. 4.1%; P = 0.014). In our study, eight out of 10 patients with gBRCA-positive PC received olaparib after platinum-based chemotherapy. The best responses to platinum-based chemotherapy included a complete response in one patient (12.5%) and a partial response in seven patients (87.5%). The median duration of treatment with platinum-based chemotherapy plus olaparib was 17.5 months (8-87 months), and the duration of treatment with olaparib maintenance therapy was 11 months (1-30 months). During olaparib maintenance therapy, three patients showed no disease progression. One of these three patients underwent conversion surgery after receiving olaparib for 12 months.

CONCLUSIONS

The gBRCA testing should be considered proactively, especially in patients with PC with a family history of HBOC-related cancer.

Familial and hereditary pancreatic cancer in Japan

As in Western countries, familial pancreatic cancer accounts for 5-7% of pancreatic cancer (PC) in Japan. Opportunities for diagnosing hereditary pancreatic cancer (HPC) are increasing owing to the coverage of companion diagnostics and cancer genomic profiling by national health insurance in patients with unresectable or recurrent PC refractory to standard chemotherapies. HPC is recognized in 7% of PCs and 15% of familial pancreatic cancer, including germline variants of BRCA1/2, ATM, PALB2, APC, and mismatch repair genes. Individuals with 5-fold or greater inherited risks of PC are recommended to undergo pancreatic surveillance according to Japanese guidelines. The imaging modalities for this surveillance include endoscopic ultrasound, magnetic resonance cholangiopancreatography, abdominal ultrasound, and enhanced computed tomography. Currently, a nationwide prospective surveillance study is ongoing in Japan. Platinum-based chemotherapy is an effective pancreatic cancer treatment in patients with variants of homologous recombination repair genes (BRCA1/2 and PALB2); however, the use of platinum regimens solely based on familial/personal cancer history remains controversial. The efficacy of olaparib maintenance therapy, as confirmed by the POLO study, has significantly impacted the clinical treatment of advanced PC patients in Japan. Since the initiation of precision cancer medicine in 2019, genetic medicine for PC patients has expanded in Japan.

The response of pancreatic acinar cell carcinoma to platinum and olaparib therapy in a germline BRCA2 variant carrier: case report and literature review

A 73-year-old Japanese man with a history of distal biliary cancer treated by pancreatoduodenectomy developed pancreatic acinar cell carcinoma (PACC) treated by remnant pancreatectomy and adjuvant chemotherapy. Thirteen months after surgery, multiple liver metastases developed and FOLFOX chemotherapy was initiated. Based on the PACC diagnosis and a positive family history for breast and ovarian cancer genetic testing was performed which revealed a pathogenic germline BRCA2 variant (c.8629G > T, p.Glu2877Ter). Olaparib therapy was initiated and the metastases responded well (partial response). PACC is a BRCA2-associated cancer which may respond well to PARP inhibitors.

Predictive Value and Therapeutic Significance of Somatic BRCA Mutation in Solid Tumors

Ten percent of patients with breast cancer, and probably somewhat more in patients with ovarian cancer, have inherited germline DNA mutations in the breast and ovarian cancer genes BRCA1 and BRCA2. In the remaining cases, the disease is caused by acquired somatic genetic and epigenetic alterations. Targeted therapeutic agents, such as poly ADP-ribose polymerases (PARP) inhibitors (PARPi), have emerged in treating cancers associated with germline BRCA mutations since 2014. The first PARPi was FDA-approved initially for ovarian cancer patients with germline BRCA mutations. Deleterious variants in the BRCA1/BRCA2 genes and homologous recombination deficiency status have been strong predictors of response to PARPi in a few solid tumors since then. However, the relevance of somatic BRCA mutations is less clear. Somatic BRCA-mutated tumors might also respond to this new class of therapeutics. Although the related literature is often controversial, recently published case reports and/or randomized studies demonstrated the effectiveness of PARPi in treating patients with somatic BRCA mutations. The aim of this review is to summarize the predictive role of somatic BRCA mutations and to provide further assistance for clinicians with the identification of patients who could potentially benefit from PARPi.

Correlation between main pancreatic duct diameter measurements: Special pancreatic ultrasonography versus magnetic resonance cholangiopancreatography

Main pancreatic duct (MPD) dilatation is reported to be a risk factor for pancreatic cancer (PC). Although magnetic resonance cholangiopancreatography (MRCP) and ultrasonographic modalities are valuable for monitoring the pancreas, there is limited information on the efficacy of different imaging modalities in measuring MPD diameter. To improve pancreatic imaging, we developed a specialized ultrasound approach focusing on the pancreas (special pancreatic US). We aimed to examine the correlation between MPD diameter measurements using special pancreatic US versus MRCP. We retrospectively reviewed the clinical data of patients with MPD dilation (≥2.5 mm) via special pancreatic US used for screening at our institution between January 2020 and October 2022 and included patients who underwent magnetic resonance imaging 2 months before and after pancreatic US. The MPD diameter on MRCP was measured at the pancreatic locus, where the maximum MPD diameter was obtained on special pancreatic US. This study included 96 patients, with a median interval of 8.5 days between the date of special pancreatic US and the date of undergoing MRCP. MPD dilatation and/or pancreatic cysts were diagnosed in 86 patients, PC in 5 patients, and other diseases in 5 patients. The median MPD diameter, measured using special pancreatic US, was 3.4 mm (interquartile range: 2.9-4.9 mm), whereas it was 3.5 mm using MRCP (interquartile range: 2.8-4.5 mm). There were strong positive correlations between MPD diameter measured on special pancreatic US and that measured on MRCP (R = 0.925, P < .001). This study revealed strong positive correlations between the MPD diameter measurements using special pancreatic US and MRCP. MPD diameter measurements from each imaging method can be helpful during follow-up in individuals at a high risk of PC.