Japanese Male Patients Research Articles

Comparison of Denosumab with Romosozumab in the treatment of male osteoporosis: a retrospective cohort study

We aimed to investigate the efficacy of romosozumab treatment compared with that of denosumab in especially male osteoporosis patients. This retrospective cohort study included 174 Japanese male patients receiving either denosumab or romosozumab for 12 months. Propensity score matching extracted 50 patients per treatment group for standardization of group characteristics. The endpoints include the rate of change in the bone mineral density (BMD) of the lumbar spine, total hip, and femoral neck after 12 months of treatment as well as the changes in serum bone metabolism markers. The mean 12-month percentage increase in the lumbar spine BMD from baseline was significantly greater with romosozumab (13.0% ±1.7%) than with denosumab (4.5%±0.6%) (P < 0.01). The total hip and femoral neck BMD exhibited a similar trend at 12 months; however, no significant between-group differences were observed. With denosumab, bone formation, and resorption marker levels significantly decreased at 6 and 12 months. Conversely, with romosozumab, the levels of bone formation markers increased transiently at 6 months before returning to baseline, whereas bone resorption markers significantly decreased at both time points. Romosozumab demonstrated significantly superior effects over denosumab in improving BMD, especially of the lumbar spine, suggesting that romosozumab can be used for treating male osteoporosis.

Efficacy of pembrolizumab plus lenvatinib as first‐line treatment for metastatic renal cell carcinoma with multiple brain metastases

IntroductionPatients with metastatic renal cell carcinoma have a poor prognosis and its specific pathogenesis remains unelucidated.Case presentationAt 78 years of age, a Japanese male patient was diagnosed with metastatic renal cell carcinoma (cT3N2M1 stage) and multiple brain metastases that were responsive to stereotactic radiation therapy followed by systemic combination induction therapy of pembrolizumab plus lenvatinib. Adverse events, including grade 3 hypertension, grade 2 eruption, and elevated grade 2 fever, were controlled by a dose reduction or suspension of drugs. The patient eventually showed a tolerance for continuing with 8 mg lenvatinib. Fourteen months after the initiation of treatment, and on 8 mg lenvatinib, this patient showed no sign of disease progression at the last follow‐up.ConclusionWe detail the absence of disease progression in a metastatic renal cell carcinoma case with multiple brain metastases more than 1 year after stereotactic radiation therapy followed by first‐line pembrolizumab plus lenvatinib.

Bilateral breast metastases from anaplastic lymphoma kinase-positive lung cancer in a male: a case report

BackgroundDistant metastases from lung cancer are commonly found in the brain, bone, and liver. Metastases to the breast from non-mammary malignancies are extremely rare, and their clinical presentations remain unclear.Case presentationWe herein report a case of bilateral breast metastases from anaplastic lymphoma kinase-positive advanced lung cancer in a 51-year-old Japanese male patient. During the course of systemic treatment for advanced lung cancer, computed tomography revealed bilateral breast enlargement without contrast enhancement, a finding consistent with gynecomastia. While other metastatic lesions responded to chemotherapy, both breast masses grew vertically like nodules. The breast masses were immunohistochemically diagnosed as metastases from lung cancer and were removed surgically. Simultaneous bilateral breast metastases from malignancies of other organs, like ones in this case, have rarely been described.ConclusionsIt is important to keep in mind that breast metastases from nonmammary malignancies are a possible explanation for unusual breast findings in a patient with a history of malignancies.

P147 EFFICACY AND SAFETY OF SACUBITRIL/VALSARTAN VERSUS AMLODIPINE IN JAPANESE PATIENTS WITH ESSENTIAL HYPERTENSION: A RANDOMIZED, OPEN-LABEL, MULTICENTER STUDY (PARASOL STUDY)

Background and Objective: Sacubitril/valsartan, an angiotensin receptor-neprilysin inhibitor, is shown to be superior to renin-angiotensin system inhibitors in terms of blood pressure (BP) lowering effect in several clinical trials. However, there is limited evidence on the BP-lowering effect of sacubitril/valsartan in comparison with amlodipine, a widely used calcium channel blocker (CCB), and potent BP-lowering effect. This study is to investigate the efficacy and safety of sacubitril/valsartan monotherapy compared with amlodipine monotherapy in Japanese patients with essential hypertension. (jRCTs051220165) Methods: This was a multicenter, randomized, open-label, parallel-group, and active-controlled study conducted in Japan. Male or female Japanese patients aged 18 to 79 with either treated or untreated mild to moderate essential hypertension were eligible for this study and randomly assigned to the sacubitril/valsartan 200 mg group or amlodipine 5 mg group. Each study drugs were administered once daily for eight weeks. The primary endpoint was to demonstrate the non-inferiority of sacubitril/valsartan versus amlodipine in mean change from baseline for 24-h systolic blood pressure (SBP) after eight weeks of treatment. Results: A total of 359 patients were randomized in this study (sacubitril/valsartan group n=182, amlodipine group n=177; mean age was 58.3 and 58.1 years, 75.3% and 74.0% were male, baseline BPs were described in Table). At week 8, mean reductions from baseline for mean 24-h SBP in sacubitril/valsartan were non-inferior to that in amlodipine (between-treatment difference: −0.6 mmHg [95% CI: −3.2 to 2.0; P=0.003 for non-inferiority, independent t-test]). In addition, other BP parameters in sacubitril/valsartan were comparable to those in amlodipine (Table). For the investigator-reported adverse events, seven hypotension-related events (3.8%) were observed in sacubitril/valsartan and three events (1.7%) in amlodipine. Conclusions: In Japanese patients with essential hypertension, the BP-lowering effect of sacubitril/valsartan was non-inferior to that of amlodipine, and no marked differences in tolerability were observed. Early initiation of sacubitril/valsartan in hypertensive patients is expected to achieve good BP control, similar to the widely used CCB.

Stereotactic body radiation therapy for multiple lung cancers in a patient with six primary cancers: a case report

BackgroundSurgery is the standard care for patients with early-stage lung cancer, and stereotactic body radiation therapy is an option for those who are medically inoperable or refuse surgery. Medical developments in diagnostic and therapeutic strategies would prolong prognosis of patients with cancer. The number of patients with multiple cancers has also increased. Duplex primary malignant neoplasms are the most common, and triple or more primary malignant neoplasms were extremely rare. This is the first case of sextuple primary malignant neoplasms with lung cancer.Case presentationWe report a case of two courses of stereotactic body radiation therapy for an 88-year-old Japanese male patient with six primary cancers in five organs. Cancers were detected in the thyroid, prostate, esophagus, bladder, and lungs. He also had a history of angina pectoris and had undergone percutaneous coronary intervention. Although he was capable of undergoing surgery for lung cancers, he refused it because he had experienced many invasive treatments, such as surgeries and percutaneous coronary intervention. In January 2020, the first stereotactic body radiation therapy was performed for the adenocarcinoma in the right lung. In March 2022, the second stereotactic body radiation therapy was performed for the nodule of the left lung. Although he complained of mild dyspnea after the first stereotactic body radiation therapy, we did not use steroids because his peripheral oxygen saturation was within the normal range. He had pleural effusion, cardiac dilatation, and pericardial effusion 2 months after the second stereotactic body radiation therapy, which improved with the use of compression stockings.ConclusionA total of 43 and 17 months have passed since the first and second stereotactic body radiation therapy, respectively, there is no local recurrence and the patient can walk independently. We safely performed stereotactic body radiation therapy twice for our older patient with metachronous early-stage lung cancers. If another new tumor is detected, stereotactic body radiation therapy would be a good treatment option for the functional preservation of organs.

Establishment and characterization of TK-ALCL1: a novel NPM-ALK-positive anaplastic large-cell lymphoma cell line.

TK-ALCL1, a novel anaplastic lymphoma kinase (ALK)-positive anaplastic large-cell lymphoma (ALK+ ALCL) cell line, was established from the primary tumor site of a 59-year-old Japanese male patient. The immune profile of TK-ALCL1 corresponds to that seen typically in primary ALCL cells, i.e., positive for ALK, CD30, EMA, and CD4, but negative for CD2, CD3, CD5, CD8a, and EBV-related antigens. The rearrangement of the T cell receptor-gamma locus shows that TK-ALCL1 is clonally derived from T-lineage lymphoid cells. FISH and RT-PCR analysis revealed that TK-ALCL1 has the nucleophosmin (NPM)-ALK fusion transcript, which is typical for ALK+ ALCL cell lines. When TK-ALCL1 was subcutaneously inoculated into 6-week-old BALB/c Rag2-/-/Jak3-/- (BRJ) mice, it formed tumor masses within 4-6weeks. Morphological, immunohistochemical, and molecular genetic investigations confirmed that the xenograft and the original ALCL tumor were identical. The ALK inhibitors Alectinib and Lorlatinib suppressed proliferation in a dose-dependent manner. Thus, TK-ALCL1 provides a useful in vitro and in vivo model for investigation of the biology of ALK+ ALCL and of novel therapeutic approaches targeting ALK.

Primary omental smooth muscle tumor in an adult male: a diagnostic dilemma for leiomyoma: a case report

BackgroundThe greater omentum comprises peritoneal, adipose, vascular, and lymphoid tissues. Most omental malignancies are metastatic tumors, and the incidence of primary tumors is rare. We report on a prior omental smooth muscle tumor case in an adult male patient.Case presentationA 54-year-old Japanese male patient with no relevant medical history was diagnosed with an abdominal mass during a routine medical checkup. Subsequent contrast-enhanced computed tomography revealed a mass of approximately 3 cm in size in the greater omentum, and a laparotomy was performed. A 27 × 25 × 20 mm raised lesion was found in the omentum. Microscopically, spindle cells were observed and arranged in whorls and fascicles. Individual tumor cells had short spindle-shaped nuclei with slightly increased chromatin and were characterized by a slightly eosinophilic, spindle-shaped cytoplasm. The mitotic count was less than 1 per 50 high-power fields. The tumor cells showed positive immunoreactivity for α smooth muscle actin, HHF35, and desmin on immunohistochemical examination. The Ki-67 labeling index using the average method was 1.76% (261/14806). No immunoreactivity was observed for any of the other tested markers. We considered leiomyoma owing to a lack of malignant findings. However, primary omental leiomyoma has rarely been reported, and it can be difficult to completely rule out the malignant potential of smooth muscle tumors in soft tissues. Our patient was decisively diagnosed with a primary omental smooth muscle tumor considering leiomyoma. Consequently, the patient did not undergo additional adjuvant therapy and was followed up. The patient was satisfied with treatment and showed neither recurrence nor metastasis at the 13-month postoperative follow-up.Discussion and conclusionWe encountered a primary smooth muscle tumor of the greater omentum with no histological findings suggestive of malignancy in an adult male patient. However, omental smooth muscle tumors are extremely difficult to define as benign, requiring careful diagnosis. Further case reports with long-term follow-up and case series are required to determine whether a true omental benign smooth muscle tumor (leiomyoma) exists. In addition, proper interpretation of the Ki-67 labeling index should be established. This case study is a foundation for future research.

Housework participation and mortality in Japanese male patients undergoing cancer surgery: A propensity score-matched study

BackgroundParticipation in housework and meal preparation are instrumental activity of daily living (IADL) evaluation items that is known to predict prognosis and complications in cancer care. However, these items are often assessed only for females, not for males, in IADL. MethodsWe examined the impact of habit of housework and meal preparation on overall survival (OS) in 1025 Japanese male patients who underwent elective urologic cancer surgery at our institution. The study also used a cohort that was matched by propensity score. ResultsWe found that patients who did not prepare meals or do housework had significantly shorter OS (hazard ratio [HR] = 3.34, P = 0.005; HR = 5.01, P < 0.001, respectively). Even in the cohort of 448 patients matched by propensity score and adjusted for age, body mass index, comorbidities, performance status, living status, cancer type, stage groups of cancer, and surgical approach, lack of participation in housework was associated with shorter OS (HR = 2.92, P = 0.04) and was an independent predictor of worse OS in multivariable analysis (HR = 5.13, P = 0.008). ConclusionsMales who did not regularly do household chores before elective cancer surgery had worse life outcomes. Doing more daily physical activities, such as household chores like making the bed and cleaning the room, might have a positive impact on survival when fighting cancer.

A Male Japanese Patient with Temple Syndrome Complicated by Type 2 Diabetes Mellitus.

We herein present the case of a 21-year-old male Japanese diabetic patient with Temple syndrome, caused by maternal uniparental disomy of chromosome 14. The patient was overweight and had type 2 diabetes, dyslipidemia, metabolic dysfunction-associated steatotic liver disease, and microalbuminuria. He had an increased fat mass in the truncal region and a decreased lean mass throughout the body. This may lead to insulin resistance due to the absence of delta-like homolog 1 (DLK1) and retrotransposon gag-like 1 (RTL1). The patient had experienced social withdrawal at home (hikikomori in Japanese), had poorly controlled type 2 diabetes, and was overweight despite receiving diet therapy and oral hypoglycemic agents.

Unresectable Ulcerative Colitis Associated Colon Cancer in a Young Japanese Patient: A Case Report.

We herein present the case of a 30-year-old Japanese male patient with ulcerative colitis (UC) who was admitted to our hospital because of significant ascites. Upon evaluation, the patient was diagnosed with unresectable UC-associated cancer (UCAC), localized in the transverse colon. Using gene profiling of the tumor tissue, anti-epidermal growth factor receptor (EGFR) antibody combination chemotherapy was selected. Subsequently, the patient exhibited a temporary response to this regimen, with an enhancement in his quality of life and he was able to survive for 12 months. This case underscores the potential benefits of aggressive chemotherapy tailored to the gene profile in UCAC treatment, offering insights into potential avenues for improving the patient prognosis.

Bridging population pharmacokinetic and semimechanistic absorption modeling of APX3330.

APX3330 ((2E)-2-[(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4-cyclohexadien-1-yl)methylene]-undecanoic acid), a selective inhibitor of APE1/Ref-1, has been investigated in treatment of hepatitis, cancer, diabetic retinopathy, and macular edema. APX3330 is administered orally as a quinone but is rapidly converted to the hydroquinone form. This study describes the pharmacokinetics of APX3330 and explores effect of food on absorption. Total plasma quinone concentrations of APX3330 were obtained following oral administration from studies in healthy Japanese male subjects (single dose-escalation; multiple-dose; food-effect) and patients with cancer patients. Nonlinear mixed effects modeling was performed using Monolix to estimate pharmacokinetic parameters and assess covariate effects. To further evaluate the effect of food on absorption, a semi-physiologic pharmacokinetic model was developed in Gastroplus to delineate effects of food on dissolution and absorption. A two-compartment, first order absorption model with lag time best described plasma concentration-time profiles from 49 healthy Japanese males. Weight was positively correlated with apparent clearance (CL/F) and volume. Administration with food led to an 80% higher lag time. CL/F was 41% higher in the cancer population. The semi-physiologic model indicates a switch from dissolution-rate control of absorption in the fasted-state to gastric emptying rate determining absorption rate in the fed-state. Oral clearance of APX3330 is higher in patients with cancer than healthy Japanese males, possibly due to reduced serum albumin in patients with cancer. Delayed APX3330 absorption with food may be related to higher conversion to the more soluble but less permeable hydroquinone form in the gastrointestinal tract. Future work should address pharmacokinetic differences between APX3330 quinone and hydroquinone forms.

Serum albumin levels as a useful complementary marker for erectile dysfunction in ulcerative colitis: A cross-sectional study.

Recently, a close association between ulcerative colitis (UC) and erectile dysfunction (ED) was reported. An inverse relationship between serum albumin and ED is found in patients with chronic disease. However, the association between serum albumin levels and ED in patients with UC is unclear. This study aims to investigate this issue in Japanese patients with UC. One hundred and thirty-six Japanese male UC patients were enrolled in this study. Information on serum albumin levels and medications for UC from medical records, Sexual Health Inventory for Men (SHIM) score information from self-administered questionnaires and information on the severity of UC from physician reports were obtained from medical records, self-administered questionnaires, and reports from physicians. The participants were divided into tertiles based on the total protein, serum globulin, serum albumin, aspartate aminotransferase, and C-reactive protein levels. The definition of ED and severe ED was SHIM score < 22 and SHIM score < 8, respectively. The association between these serum markers and ED was assessed by multivariate logistic regression. The prevalence of severe ED in the low, moderate, and high albumin groups was 66.0%, 51.0%, and 28.3%, respectively. After adjusting for confounding factors, the low albumin group was independently and positively associated with severe ED (adjusted odds ratio: 2.74, 95% confidence interval: 1.03-7.48, p for trend =0.044). No association between other marker and ED was found. Serum albumin was independently inversely associated with severe ED in Japanese patients with UC. Hypoalbuminemia might be a useful complementary marker for assessing the prevalence and severity of ED in UC patients.

The Development of Acquired Amegakaryocytic Thrombocytopenia in a Patient with Idiopathic Thrombocytopenic Purpura

A 67-year-old Japanese male patient with Helicobacter pylori infection developed severe thrombocytopenia and was diagnosed with primary immune thrombocytopenia (ITP) on December 22, 2021. He was treated with Helicobacter pylori eradication therapy, corticosteroids, and eltrombopag (ELT). The platelet count (PLT) improved rapidly; however, after ELT cancellation and corticosteroid reduction, the PLT swiftly decreased. When the corticosteroid dose was increased, the PLT rapidly increased. The corticosteroid dose was reduced immediately; however, the patient presented with subacute arterial obstruction in the right leg and ultimately underwent surgical thrombectomy and transmetatarsal amputation. After corticosteroid cancellation, the PLT again decreased swiftly. Corticosteroids and ELT were thus re-administered. The PLT showed a tendency to recover temporarily, although the drug reaction was not gradual and showed a tendency to decrease. After a repeated BM aspiration, only megakaryocytes were not detected. We determined that the pathogenesis of the severe thrombocytopenia converted from ITP to acquired amegakaryocytic thrombocytopenia (AAMT). Cases of a conversion from ITP to AAMT are extremely rare, and the mechanism underlying this conversion is not well understood. Herein, we report the first case, to the best of our knowledge, in which transmetatarsal amputation triggered the progression of ITP to AAMT.

Excellent Blood Glucose Levels for 5 Years with Well Maintained Insulin Secretion by the Treatment Comprising a Once-Weekly Injection of Dulaglutide: GLP- 1RA Alone in a Patient with Type 2 Diabetes Mellitus

As a result of worsening of diabetes mellitus control to 9.1% hemoglobin A1c, a 61-year-old male Japanese patient began treatment with once-weekly subcutaneous injection of 0.75mg dulaglutide (a glucagon-like peptide-1 receptor agonist) alone. As a result, he demonstrated excellent diabetes mellitus control at an approximate 6.0% to 6.7% hemoglobin A1c level with this treatment alone for 5 years. The insulin secretion activity was well maintained as assessed by the HOMA-β score from 2.7 to 10.2. Interestingly, slight increase of insulin resistance, as assessed by the HOMA-IR was observed from 0.7 to 1.1. Taken together, the mild increase of insulin secretion may have been a positive reaction to keep good control of diabetes mellitus in response to slightly increased insulin resistance. Thus, a long-lasting favorable effect of treatment with dulaglutide alone, not only for diabetes mellitus control, but also for keeping insulin secretion, was demonstrated by this patient.

Meningitis caused by Chromobacterium haemolyticum suspected to be derived from a canal in Japan: a case report

BackgroundThe genus Chromobacterium, of which 12 species have been recognized, comprises bacteria that reside in tropical and subtropical environments. Of these species, Chromobacterium violaceum and Chromobacterium haemolyticum are known to cause infections in humans. There have been few reports of infections caused by Chromobacterium haemolyticum.Case presentationChromobacterium haemolyticum was detected in spinal fluid and blood samples isolated from a 73-year-old Japanese male patient who fell into a canal in Kyoto City, Japan and developed bacteremia and meningitis. Although meropenem and vancomycin were administered, this patient died 9 days after admission. Although the infection was misidentified as being caused by Chromobacterium violaceum by conventional identification methods, average nucleotide identity analysis revealed that the causative pathogen was Chromobacterium haemolyticum. The same bacteria were also detected in the canal in which the accident occurred. Phylogenetic analysis of the strain isolated from the patient and the strain isolated from the canal suggested that the two strains were very closely related.ConclusionsChromobacterium haemolyticum can be misidentified as Chromobacterium violaceum by conventional identification methods and tends to be more resistant to β-lactams than Chromobacterium violaceum. Pigment production and β-hemolysis on blood sheep agar can provide clues for the early identification of Chromobacterium haemolyticum.

Japanese patients need slower, personalized clozapine titrations: A comment on the case described by Kikuchi et al.

Japanese patients need slower, personalized clozapine titrations: A comment on the case described by Kikuchi et al.

Rapid Clinical Improvement of Multicentric Castleman Disease (MCD) with Renal Involvement Following Treatment with Tocilizumab: AA Amyloidosis as a Possible Renal Involvement of MCD.

Castleman disease (CD) is a lymphoproliferative disorder that manifests as hypergammaglobulinemia and severe inflammation with multiorgan involvement. However, renal involvement has been infrequently described in CD. We present a case of a 63-year-old Japanese male patient with multicentric CD (MCD) in whom kidney involvement, including impaired renal function and massive proteinuria, is present. He had a 2-year history of inflammatory arthritis and was referred to our clinic with newly developed proteinuria, renal dysfunction, and elevated levels of acute-phase proteins. Abdominal computed tomography scan revealed hepatosplenomegaly, including mesenteric and inguinal lymph node enlargements. The patient underwent inguinal lymph node resection. Excisional biopsy of the inguinal lymph node showed multiple lymphoid follicles and expansion of interfollicular areas by marked plasmacytosis consistent with mixed type CD. The patient was diagnosed with human herpes virus 8-negative MCD according to the international diagnostic criteria for CD. Diagnostic renal biopsy was not performed following the medical viewpoint. Tocilizumab (TCZ) treatment was highly effective in reducing proteinuria and stabilizing renal function, as well as improving other clinical symptoms. The patient responded to TCZ treatment, and the renal involvement was rapidly improved. Our preliminary immunohistochemical analysis indicated AA amyloid deposits in urinary epithelial cells suggesting a possible renal involvement of AA amyloidosis. TCZ could potentially be one of the therapeutic options in patients with MCD with renal involvement.

Acquired hemophilia A that developed after BNT162b2 mRNA COVID-19 vaccination and worsened following re-vaccination

An 86-year-old Japanese male patient visited a nearby hospital with painful swelling in his left upper and lower limbs 35 days after the second dose of the BNT162b2 mRNA coronavirus disease-2019 (COVID-19) vaccine. He was referred to our hematological department due to a prolonged activated partial thromboplastin time and was urgently admitted. He was diagnosed with acquired hemophilia A (AHA) based on factor VIII (FVIII) activity of 1.7%, FVIII inhibitor of 152.3 BU/ml, and FVIII-binding antibodies detected by enzyme-linked immunosorbent assay. Immunosuppressive therapy with prednisolone (PSL) at 0.5 mg/kg/day was started owing to the risk of infection due to old age and poor activities of daily living. Hemostasis treatment with bypass hemostatic preparations (rFVIIa preparation, FVIIa/FX) was administered for each bleeding event, such as intramuscular and knee joint bleeding, resulting in good hemostatic effects. Coagulative complete remission was achieved on day 69 with PSL treatment; however, FVIII activity decreased with PSL tapering. AHA relapse with rectus abdominis muscle hematoma was observed after the third vaccination. This is the first Japanese report of AHA after COVID-19 vaccination and the world's first case, in which the presence of anti-FVIII-binding antibodies were observed.

CASE REPORT OF ICU ADMISSION DUE TO LEGIONELLA PNEUMOPHILA SEVERE PNEUMONIA IN VIET NAM

Legionnaires’ disease is a serious type of atypical pneumonia caused by Legionella bacteria. In this case study, the first case of ICU admission due to Legionella pneumophila severe infection in Vietnam is reported. A 40-year-old Japanese male patient with a history of hypertension for over 4 years was hospitalized with fever and frequent breathing difficulties. Diagnosis upon hospitalization was sepsis shock and ARDS pulmonary consolidation. The sputum specimen was then tested with multiplex PCR using Film array panel and the result was positive with Legionella pneumophila detection. The patient was medicated according to the results ofbacterial identification which gave good response and was discharged after 22 days of treatment.

Clinicopathological features, genetic alterations, and BRCA1 promoter methylation in Japanese male patients with breast cancer

PurposeMale breast cancer (MBC) is a rare cancer accounting for only 1% of all male cancers and is, therefore, poorly studied. We aimed to characterize the subtypes of MBC in Japanese patients based on genetic profiling, the presence of tumor-infiltrating cells, and the expression of immunohistochemical markers.MethodsThis retrospective study included 103 patients with MBC diagnosed between January 2009 and December 2019 at various hospitals in Japan. Clinicopathological patient characteristics were obtained from medical records, and formalin-fixed paraffin-embedded tissue specimens were analyzed for histological markers, mutations of 126 genes, BRCA1 methylation, and stromal tumor-infiltrating lymphocytes.ResultsThe median patient age was 71 (range 31–92) years. T1-stage tumors were the most frequent (47.6%), and most were node negative (77.7%). The majority of tumors were positive for estrogen receptor (98.1%), progesterone receptor (95.1%), and androgen receptor (96.1%), and BRCA2 was the most frequently mutated gene (12.6%). The most common treatment was surgery (99.0%), either total mastectomy (91.1%) or partial mastectomy (7.0%). Survival analysis showed a 5-year recurrence-free survival rate of 64.4% (95% confidence interval [CI] 46.7–88.8) and a 5-year overall survival rate of 54.3% (95% CI 24.1–100.0).ConclusionJapanese MBC is characterized by a high rate of hormonal receptor positivity and BRCA2 somatic mutation. Due to the observed clinicopathological differences in MBC between the Western countries and Japan, further prospective studies are needed to evaluate the most suitable treatment strategies.