Availability of genome-matched therapy based on clinical practice.

BACKGROUND: Comprehensive genomic profiling (CGP) provides new opportunities for patients with advanced cancer to receive genome-matched therapies, but the availability rate of these remains low. We reviewed our CGP cases and suggested possible strategies to improve the current status from a clinical perspective. METHODS: Druggable genomic alterations and barriers to accessing genome-matched therapies were investigated in 653 patients with 30 various types of cancers who underwent CGP. RESULTS: While the availability rate of genome-matched therapies as a whole was 9.5%, CGP was useful in some cancer types. Patients with thyroid cancer and lung cancer harbored druggable genomic alterations at high rates, while sarcoma rarely harbored these alterations (100%, 76%, and 15.2%, respectively). In contrast, the availability rate of genome-matched therapies was highest in patients with sarcoma and head and neck cancer (HNC) (60% and 40%, respectively). One hundred thirteen patients (63.5%) had multiple barriers to accessing genome-matched therapy. Of 178 patients, 21 patients (11.8%) could not be considered for genome-matched therapies solely because of the deterioration of their performance status. CONCLUSION: This study demonstrated the usefulness of CGP for patients with sarcoma and HNC in addition to lung cancer in clinical practice. Performing CGP at the front line has the potential to improve the availability of genome-matched therapy.

Risk of metachronous colorectal cancer after surgical resection of index rectal cancer in Lynch syndrome: a multicenter retrospective study in Japan.

PURPOSE: This study evaluated the risk of metachronous colorectal cancer (CRC) after resection of index (first) rectal cancer in patients with Lynch syndrome (LS). METHODS: Clinicopathological data of patients with genetically proven LS were retrospectively analyzed in this multicenter Japanese study. The cumulative incidence of metachronous CRC and the overall survival were compared between patients with index rectal cancer (rectal group) and those with index colon cancer (colon group). RESULTS: The median age at index CRC surgery was lower in the rectal group than in the colon group (37 vs. 46 years old, P = 0.01). The cumulative 5-, 10-, and 20-year incidences of metachronous CRC were 3.5%, 13.9%, and 21.1%, respectively, in the rectal cancer group and 14.9%, 22.0%, and 57.9%, respectively, in the colon cancer group (P = 0.02). The overall survival curves were not significantly different between two groups (P = 0.23). CONCLUSION: This is the first report from an East Asian country to report the risk of metachronous CRC after resection of index rectal cancer in patients with LS. Despite this study having several limitations, we cannot recommend extended resection, such as total proctocolectomy, for index rectal cancer as a standard surgical treatment in patients with LS.

Current prospects of hereditary adrenal tumors: towards better clinical management.

Adrenocortical carcinoma (ACC) and pheochromocytoma/paraganglioma (PPGL) are two rare types of adrenal gland malignancies. Regarding hereditary tumors, some patients with ACC are associated with with Li-Fraumeni syndrome (LFS), and those with PPGL with multiple endocrine neoplasia type 2. Recent studies have expanded this spectrum to include other types of hereditary tumors, such as Lynch syndrome or familial adenomatous polyposis. Individuals harboring germline TP53 pathogenic variants that cause LFS have heterogeneous phenotypes depending on the respective variant type. As an example, R337H variant found in Brazilian is known as low penetrant. While 50-80% of pediatric ACC patients harbored a LFS, such a strong causal relationship is not observed in adult patients, which suggests different pathophysiologies between the two populations. As for PPGL, because multiple driver genes, such as succinate dehydrogenase (SDH)-related genes, RET, NF1, and VHL have been identified, universal multi-gene germline panel testing is warranted as a comprehensive and cost-effective approach. PPGL pathogenesis is divided into three molecular pathways (pseudohypoxia, Wnt signaling, and kinase signaling), and this classification is expected to result in personalized medicine based on genomic profiles. It remains unknown whether clinical characteristics differ between cases derived from genetic predisposition syndromes and sporadic cases, or whether the surveillance strategy should be changed depending on the genetic background or whether it should be uniform. Close cooperation among medical genomics experts, endocrinologists, oncologists, and early investigators is indispensable for improving the clinical management for multifaceted ACC and PPGL.

Ovarian surveillance including endometrial cytology for patients with hereditary breast and ovarian cancer before risk-reducing salpingo-oophorectomy: A retrospective analysis.

AIM: Ovarian surveillance in women with hereditary breast and ovarian cancer who do not undergo risk-reducing salpingo-oophorectomy has been controversial. Therefore, this study aimed to demonstrate the clinical features of ovarian surveillance at our institution using a technique that combines serum cancer antigen 125 measurements, transvaginal ultrasonography, and uterine endometrial cytology. METHODS: We retrospectively examined 65 women, who had not undergone risk-reducing salpingo-oophorectomy diagnosed with hereditary breast and ovarian cancer between 2000 and 2021 at our hospital. Clinical information was obtained and analyzed through a chart review. The details of the treatment course were reviewed for patients who had developed ovarian cancer. RESULTS: Overall, 5 of the 65 women were diagnosed with ovarian cancer based on abnormal findings during periodic surveillance. All patients who developed ovarian cancer were asymptomatic, even if the cancer was at an advanced stage. Two of the 65 patients had endometrial cytology abnormalities, both of whom had ovarian cancer. All patients who developed ovarian cancer underwent primary debulking surgery, and complete gross resection was achieved. None of the patients experienced ovarian cancer recurrence. CONCLUSIONS: The ovarian surveillance strategy at our institution for women with hereditary breast and ovarian cancer who do not undergo risk-reducing salpingo-oophorectomy can identify asymptomatic ovarian cancer and contribute to achieving complete gross resection during primary surgery. Ovarian surveillance may contribute to a reduction in ovarian cancer mortality.

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.

Prognostic impact of cancer genomic profile testing for advanced or metastatic solid tumors in clinical practice.

Cancer genomic profile (CGP) testing, which is covered by the national health insurance system in Japan, has been introduced as a routine clinical practice. However, the effects of CGP testing on prognoses remain unclear. Drug accessibility rates and prognoses after CGP testing were retrospectively investigated in 713 patients who underwent CGP testing examined by our molecular tumor board between November 2019 and October 2022,. Overall survival (OS) was examined using the log-rank test and the Kaplan-Meier method. The median age of patients (326 males and 387 females) was 58 years (12-85 years). CGP testing revealed one or more gene mutations in 681 cases (95.5%), among which actionable gene mutations were detected in 439 (61.6%). Although treatment options were recommended for 285 cases (40.0%) by the molecular tumor board, only 45 received treatment based on their gene mutations. During the median observation period of 8.6 months, 351 (49.2%) patients died of the exacerbation of existing diseases. No significant differences were observed in OS between patients treated with and without genomically matched therapy (p = 0.285). According to clinical responses to treatment based on gene mutations, median OS was significantly longer in patients who achieved partial response and stable disease (26.5 months; 95% CI 14.4-38.6) than in those with progressive disease and not evaluated (9.8 months; 95% CI 5.8-13.8, p = 0.013). Responses to treatment based on gene mutations may improve prognoses, and it is important to increase the drug accessibility rate after CGP testing.

A case of sequential medical therapy for advanced ureteral cancer in Li-Fraumeni syndrome.

Introduction: Li-Fraumeni syndrome, an autosomal dominant cancer predisposition syndrome caused by a pathogenic variant of TP53, a tumor suppressor gene, leads to a high risk from early childhood of developing various types of cancers. Here, we report a case of advanced ureteral cancer in Li-Fraumeni syndrome. Case presentation: A 73 years-old female patient, who had been diagnosed genetically as Li-Fraumeni syndrome; suffered from chondrosarcoma in the left pelvic joint, bilateral breast cancer, endometrial cancer, gastric cancer, and colon cancer in her history. She was diagnosed as unresectable advanced urothelial cancer during continuous magnetic resonance imaging surveillance, underwent avelumab maintenance therapy after the combination of gemcitabine and cisplatin chemotherapy. The efficacies of gemcitabine and cisplatin chemotherapy and avelumab maintenance therapy were good. Conclusion: We report an advanced urothelial cancer in a patient with Li-Fraumeni syndrome who demonstrated good efficacies to sequential medical therapy.

Risk of metachronous colorectal cancer after colectomy for first colon cancer in Lynch syndrome: multicenter retrospective study in Japan.

BACKGROUND: We evaluated the risk of metachronous colorectal cancer (mCRC) and explored the optimal extent of colectomy in patients with Lynch syndrome (LS) and first colon cancer (fCC) in Japan, where the extent of colectomy for colon cancer (CC) is shorter than that in Western countries. METHODS: The clinicopathologic and survival data of patients with LS who developed CC were collected from a nationwide database and analyzed retrospectively. The cumulative incidence of mCRC after actual segmental colectomy was compared with that of mCRC when more extensive colectomy was assumed. RESULTS: There were 142 eligible patients (65 female). The median age at fCC surgery was 46.5 (range: 14-80) years. The cumulative incidence of 5-, 10-, and 20-year mCRC rate was 13.4%, 20.8%, and 53.6%, respectively. The incidence was higher in the left-sided group (splenic flexure to rectosigmoid colon, n = 54) than in the right-sided group (cecum to transvers colon, n = 88) (66.3% vs. 45.3% in 20 years, P < 0.01). Assuming that all patients would have undergone hemicolectomy or total colectomy, the estimated mCRC risk was 41.5% and 9.4% (P < 0.01, vs. actual procedures), respectively. The 20-year overall survival rate of all the patients was 83.3% without difference by fCC sidedness (P = 0.38). CONCLUSIONS: To reduce the incidence of mCRC, patients with genetically diagnosed LS and fCC, preferentially located in the left-sided colon, may need to undergo more extended colectomy than that usually performed in Japan. However, such extended colectomy should be counterbalanced with favorable overall survival and actual risk of mCRC development.

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

Opportunities for genetic counseling and germline BRCA1/2 (BRCA) testing are increasing in Japan owing to cancer genomic profiling testing and companion diagnostics being covered by national health insurance for patients with BRCA-related cancers. These tests are useful not only to judge whether platinum agents and PARP inhibitors are indicated but also to reveal an autosomal-dominant inherited cancer syndrome: hereditary breast and ovarian cancer. In individuals with germline BRCA variants, risk of cancers of the breast, ovary, pancreas, and prostate is significantly increased at various ages of onset, but the stomach, uterus, biliary tract, and skin might also be at risk. For women with pathogenic BRCA variants, breast awareness and image analyses should be initiated in their 20s, and risk-reducing procedures such as mastectomy are recommended starting in their 30s, with salpingo-oophorectomy in their late 30s. For male BRCA pathogenic variant carriers, prostatic surveillance should be applied using serum prostate-specific antigen starting in their 40s. For both sexes, image examinations ideally using endoscopic ultrasound and magnetic resonance cholangiopancreatography and blood testing should begin in their 50s for pancreatic surveillance. Homologous recombination pathway-associated genes are also causative candidates. Variant pathogenicity needs to be evaluated every 6-12 months when results are uncertain for clinical significance. Genetic counseling needs to be offered to the blood relatives of the pathogenic variant carriers with suitable timing. We review the recommended cross-organ BRCA risk management in Japan.

Clinical predominance of whole-exome sequencing to evaluate microsatellite instability status.

The microsatellite instability (MSI)/mismatch repair (MMR) status is one of the critical genomic biomarkers for predicting patient response to immune checkpoint inhibitors (ICIs). In this study, we aimed to investigate the concordance among the MSIsensor score obtained from whole-exome sequencing (WES), which could be a futuristic clinical cancer sequencing method, using only tumor tissues, MSI-PCR results, and immunohistochemistry (IHC) results to analyze various solid cancer types. We first endeavored to set the cut-off value of MSIsensor to determine functional deficient mismatch repair (f-dMMR) status. The MSI status of 1054 patients analyzed using WES was evaluated using MSIsensor. In addition, 87 of these patients were further analyzed using MSI-PCR and MMR IHC to calculate the sensitivity and specificity of the MSIsensor cut-off score. Our results showed that score 12.5 was an adequate cut-off score equivalent to PCR-confirmed MSS/MSI-low and MSI-high statuses, with sensitivity, specificity, and area under the curve values of 95.2%, 100%, and 0.998, respectively. Moreover, we identified false-positive cases of tumors with high mutational burden with an MSIsensor score <12.5, and optional IHC examination could rescue these cases. In conclusion, the MSIsensor score obtained using WES with tumor tissue showed a high clinical validity, with a cut-off value of 12.5 for f-dMMR detection, in combination with optional IHC analysis for MMR. Our novel algorithm will provide insights into the development of ICIs for cancer treatment, particularly when WES becomes a more common cancer genomic test in the near future.

The pathogenic role of the BRCA2 c.7847C>T (p.Ser2616Phe) variant in breast and ovarian cancer predisposition.

Substantial numbers of variants of unknown significance (VUSs) have been identified in BRCA1/2 through genetic testing, which poses a significant clinical challenge because the contribution of these VUSs to cancer predisposition has not yet been determined. Here, we report 10 Japanese patients from seven families with breast or ovarian cancer harboring the BRCA2 c.7847C>T (p.Ser2616Phe) variant that was interpreted as a VUS. This variant recurs only in families from Japan and has not been reported in the global general population databases. A Japanese patient with Fanconi anemia with compound heterozygous variants c.7847C>T (p.Ser2616Phe) and c.475+1G>A in BRCA2 was reported. In silico predictions and quantitative cosegregation analysis suggest a high probability of pathogenicity. The clinical features of the variant carriers were not specific to, but were consistent with, those of patients with hereditary breast and ovarian cancer. A validated functional assay, called the mixed-all-nominated-in-one-BRCA (MANO-B) method and the accurate BRCA companion diagnostic (ABCD) test, demonstrated the deleterious effects of the variant. Altogether, following the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines, this variant satisfied the "PS3," "PM2," "PM3," and "PP3" criteria. We thus conclude that the BRCA2 c.7847C>T (p.Ser2616Phe) variant is a "likely pathogenic" variant that is specifically observed in the Japanese population, leading to a breast and ovarian cancer predisposition.

Effectiveness and tasks of breast MRI surveillance for high-risk women with cancer susceptibility genes other than BRCA1/2: a single institution study.

BACKGROUND: In Japan, with the introduction of multigene panel testing, there is an urgent need to build a new medical system for hereditary breast cancer patients that covers pathogenic variants other than BRCA1/2. The aim of this study was to reveal the current status of breast MRI surveillance for high-risk breast cancer susceptibility genes other than BRCA1/2 and the characteristics of detected breast cancer. METHODS: We retrospectively examined 42 breast MRI surveillance with contrast performed on patients with hereditary tumors other than BRCA1/2 pathogenic variants at our hospital from 2017 to 2021. MRI exams were evaluated independently by two radiologists. Final histopathological diagnosis for malignant lesions were obtained from surgical specimen. RESULTS: A total of 16 patients included TP53, CDH1, PALB2, ATM pathogenic variants and 3 variant of unknown significance. 2 patients with TP53 pathogenic variants were detected breast cancer by annual MRI surveillance. The rate of cancer detection was 12.5% (2/16). One patient was detected synchronous bilateral breast cancer and unilateral multiple breast cancers (3 lesions in 1 patient), so there were 4 malignant lesions in total. Surgical pathology of 4 lesions were 2 ductal carcinoma in situ, 1 invasive lobular carcinoma, and 1 invasive ductal carcinoma. MRI findings of 4 malignant lesions were detected as 2 non mass enhancement, 1 focus and 1 small mass. All of 2 patients with PALB2 pathogenic variants had previously developed breast cancer. CONCLUSIONS: Germline TP53 and PALB2 were strongly associated with breast cancer, suggesting that MRI surveillance is essential for breast cancer-related hereditary predisposition.

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.

A radiological complete response to pembrolizumab in a patient with metastatic upper urinary tract urothelial cancer and Lynch syndrome.

Introduction: In Lynch syndrome, urothelial cancer is the third most common cancer, following colorectal and endometrial cancers. Little is known, however, about the efficacy of immune checkpoint inhibitors in the treatment of metastatic urothelial cancer in Lynch syndrome. Case presentation: A 49-year-old patient with metastatic urothelial cancer underwent pembrolizumab therapy after platinum-containing chemotherapy. The efficacy of the pembrolizumab therapy was good. Her lung and bone metastatic lesions disappeared in imaging studies and her back pain decreased dramatically. Pathogenic mutations of MSH2 and BRCA2 were found in the DNA extracted from her tumor, and subsequent genetic analysis confirmed the germline pathogenic variant of MSH2. As such, this case was genetically diagnosed as Lynch syndrome. Conclusion: We report metastatic urothelial cancer in a patient with Lynch syndrome who demonstrated a radiological complete response to pembrolizumab therapy. Accurate genetic diagnosis can provide useful information to both the patient and their relatives.

Implementation of microsatellite instability testing for the assessment of solid tumors in clinical practice.

BACKGROUND: In Japan, microsatellite instability (MSI) testing for solid tumors was introduced in clinical practice in December 2018. Although immune checkpoint inhibitors (ICIs) are established standards of care for patients with MSI-high tumors, the status of implementing MSI testing in clinical practice remains unclear. METHODS: We retrospectively reviewed the medical records of patients with solid tumors who underwent MSI testing between January 2019 and December 2020 at our institution. RESULTS: In total, 1,052 MSI tests were performed in 1,047 patients. Regardless of specimen volume and condition, the MSI status was successfully determined in 1,041 (99.0%) tests, encompassing 27 tumor types (microsatellite stable [MSS] or MSI-low: n = 991 [95.2%] and MSI-high: n = 50 [4.8%]). Patients whose specimens were fixed with 20% neutral buffered formalin (NBF) and who had specimens with prolonged storage (98.4% and 95.4%) showed lower success rates than those whose specimens were fixed with 10% NBF and who had specimens with nonprolonged storage (100.0% and 99.6%), respectively. The prolonged turnaround time (TAT) in MSI-high cases (median TAT: 24 days) was a critical issue that directly resulted in treatment delay. Of the 50 patients with MSI-high tumors, 24 (48.0%) received ICIs and 34 (68.0%) were referred to the Department of Clinical Genetic Oncology where 6 (12.0%) patients were diagnosed with Lynch syndrome. CONCLUSIONS: MSI testing was successfully performed for various types of tumors and specimens in clinical practice. Our study results identified certain issues associated with the clinical implementation of MSI testing, including optimal specimen selection, extended TAT in MSI-high cases, and awareness of hereditary tumors.

Moderate-Risk Genes for Hereditary Ovarian Cancers Involved in the Homologous Recombination Repair Pathway.

Approximately 20% of cases of epithelial ovarian cancer (EOC) are hereditary, sharing many causative genes with breast cancer. The lower frequency of EOC compared to breast cancer makes it challenging to estimate absolute or relative risk and verify the efficacy of risk-reducing surgery in individuals harboring germline pathogenic variants (GPV) in EOC predisposition genes, particularly those with relatively low penetrance. Here, we review the molecular features and hereditary tumor risk associated with several moderate-penetrance genes in EOC that are involved in the homologous recombination repair pathway, i.e., ATM, BRIP1, NBN, PALB2, and RAD51C/D. Understanding the molecular mechanisms underlying the expression and function of these genes may elucidate trends in the development and progression of hereditary tumors, including EOC. A fundamental understanding of the genes driving EOC can help us accurately estimate the genetic risk of developing EOC and select appropriate prevention and treatment strategies for hereditary EOC. Therefore, we summarize the functions of the candidate predisposition genes for EOC and discuss the clinical management of individuals carrying GPV in these genes.

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.

Druggable gene alterations in Japanese patients with rare malignancy.

Without a current standard of care, patients with rare malignancy are subjected to precision oncology with next-generation sequencing to identify a course of treatment. We sought to establish the clinical relevance of comprehensive genomic profiling (CGP) among patients with rare malignancy. Rare malignancy was defined using the Rare Cancers in Europe definition (<6 cases per 100,000 individuals). We analyzed gene mutations, fusions, tumor mutational burden (TMB), and microsatellite instability (MSI) status. Level A gene alterations, categorized using Clinical Interpretations of Variants in Cancer and MD Anderson Knowledge Base for Precision Oncology, were considered druggable. Rare malignancy accounted for 149 (45%) cases, with female genital cancers (32%) most common. Among the rare malignancy cases, we identified a lower frequency of mutation in TP53 (41% vs. 60%, P<0.001), KRAS (13% vs. 43%, P<0.001) and APC (3% vs. 25%, P<0.001), and a higher frequency of ARID1A mutation (14% vs. 6%, P=0.03), as compared with common malignancies. TMB-high and MSI-high cases were found in 8% and 2% of cases, respectively. Druggable alterations were detected in 37 patients with rare malignancy; this percentage tended to be higher than that for patients with common malignancies (25% vs. 17%, P=0.08). Common druggable alterations were BRAF V600E, ERBB2 amplification, PIK3CA E542K, and BRCA1/2 variant. Five of the 37 patients with druggable alterations received genome-driven treatment. There was no significant difference in overall survival between the rare and common malignancy groups. Our results provide clues for future clinical development and treatment success among Japanese patients with rare cancers.

Frequency and clinical features of deficient mismatch repair in ovarian clear cell and endometrioid carcinoma.

OBJECTIVE: To clarify the frequency of deficient mismatch repair (dMMR) in Japanese ovarian cancer patients, we examined microsatellite instability (MSI) status and immunohistochemistry (IHC) subtypes, including endometrioid carcinoma (EMC), clear cell carcinoma (CCC), or a mixture of both (Mix). METHODS: We registered 390 patients who were diagnosed with EMC/CCC/Mix between 2006 and 2015 and treated at seven participating facilities. For 339 patients confirmed eligible by the Central Pathological Review Board, MSI, IHC, and MutL homolog 1 methylation analyses were conducted. The tissues of patients with Lynch syndrome (LS)-related cancer histories, such as colorectal and endometrial cancer, were also investigated. RESULTS: MSI-high (MSI-H) status was observed in 2/217 CCC (0.9%), 10/115 EMC (8.7%), and 1/4 Mix (25%). Additionally, loss of MMR protein expression (LoE-MMR) was observed in 5/219 (2.3%), 16/115 (14.0%), and 1/4 (25%) patients with CCC, EMC, and Mix, respectively. Both MSI-H and LoE-MMR were found significantly more often in EMC (p<0.001). The median (range) ages of patients with MMR expression and LoE-MMR were 54 (30-90) and 46 (22-76) (p=0.002), respectively. In the multivariate analysis, advanced stage and histological type were identified as prognostic factors. CONCLUSION: The dMMR rate for EMC/CCC was similar to that reported in Western countries. In Japan, it is assumed that the dMMR frequency is higher because of the increased proportion of CCC.