Pulmonary interstitial glycogenosis in Birt-Hogg-Dubé syndrome-associated lung cysts: A new insight into the pathogenesis?

Multiple lung cysts are one of the major features of Birt-Hogg-Dubé syndrome (BHD), but little is known about their nature and pathogenesis. We report a case of a woman diagnosed with BHD lung cysts who exhibited pulmonary interstitial glycogenosis (PIG), a mesenchymal abnormality hitherto undescribed in this disease, in specimens resected at 14 and 29 years of age. Histopathologically, oval to spindle clear cells were seen in the subepithelial interstitial tissue of septal structures and the walls of the cysts. They had abundant periodic acid-Schiff-positive cytoplasmic glycogen. Immunohistochemically, these cells were positive for a few markers of mesenchymal stem cell-like lineage, including vimentin, CD44, and CD10, and negative for markers of epithelial or specific mesenchymal differentiation; these results were consistent with the reported immunophenotype of PIG cells. These PIG cells were more abundant in her specimen at age 14 years than in the second specimen from adulthood. The present case suggests that BHD lung cysts belong to a group of pulmonary developmental disorders characterized by combined PIG and alveolar simplification/cystic change. Disorders with PIG may persist until adulthood and may be of clinical and pathological significance.

Multiple Immunofluorescence Imaging Analysis Reveals Differential Expression of Disialogangliosides GD3 and GD2 in Neuroblastomas.

BACKGROUND: Peripheral neuroblastic tumors (pNTs) are the most common childhood extracranial solid tumors. There are several therapeutic strategies targeting disialoganglioside GD2. Disialoganglioside GD3 has become a potential target. However, the mechanism by which pNTs express GD3 and GD2 remains unclear. We investigated the combined expression status of GD3 and GD2 in pNTs and delineated their clinicopathological values. METHODS: GD3 and GD2 expression was examined in pNT tissue samples (n = 35) using immunohistochemistry and multiple immunofluorescence imaging. RESULTS: GD3 and GD2 expression was positive in 32/35 and 25/35 samples, respectively. Combinatorial analysis of GD3 and GD2 expression in neuroblastoma showed that both were heterogeneously expressed from cell to cell. There were higher numbers of GD3-positive and GD2-negative cells in the low-risk group than in the intermediate-risk (P = 0.014) and high-risk (P = 0.009) groups. Cases with high proportions of GD3-positive and GD2-negative cells were associated with the International Neuroblastoma Staging System stage (P = 0.004), Children's Oncology Group risk group (P = 0.001), and outcome (P = 0.019) and tended to have a higher overall survival rate. CONCLUSION: We demonstrated that neuroblastomas from low-risk patients included more GD3-positive and GD2-negative cells than those from high-risk patients. Clarifying the heterogeneity of neuroblastoma aids in better understanding the biological characteristics and clinical behavior.

Role of Postmastectomy Radiotherapy After Neoadjuvant Chemotherapy in Breast Cancer Patients: A Study from the Japanese Breast Cancer Registry.

BACKGROUND: The role of postmastectomy radiotherapy (PMRT) in breast cancer patients receiving neoadjuvant chemotherapy (NAC) is controversial. We aimed to evaluate the effectiveness of radiotherapy in patients treated with NAC and mastectomy in the Japanese Breast Cancer Registry. METHODS: We enrolled patients who received NAC and mastectomy for cT1-4 cN0-2 M0 breast cancer. We evaluated the association between radiotherapy and outcomes, locoregional recurrence (LRR), distant disease-free survival (DDFS), and overall survival (OS) based on ypN status by multivariable analysis. RESULTS: Of the 145,530 patients, we identified 3226 who met the inclusion criteria. Among ypN1 patients, no differences were found in LRR, DDFS, or OS between groups with and without radiotherapy (p = 0.72, p = 0.29, and p = 0.36, respectively). Radiotherapy was associated with improved LRR-free survival (p < 0.001), DDFS (p = 0.01), and OS (p < 0.001) in patients with ypN2-3. Multivariable analysis demonstrated that use of radiotherapy was independently associated with improved LRR [hazard ratio (HR) 0.61, 95% confidence interval (CI) 0.45-0.82, p = 0.001] and OS [HR 0.69, 95% CI 0.53-0.89, p = 0.004) for ypN2-3 patients only. The association between radiotherapy and OS was not statistically significant among ypN0 (p = 0.22) and ypN1 patients (p = 0.51). CONCLUSIONS: The results from this nationwide database study did not show significant associations between PMRT and improved survival among ypN0 and ypN1 patients. Radiotherapy may be beneficial only for ypN2-3 breast cancer patients who receive NAC and mastectomy in the modern era.

[A Case of Advanced Gastric Cancer with Bone Marrow Metastasis Treated with Low-Dose Combination Chemotherapy Containing S-1 and Docetaxel].

A 77-year-old woman was admitted to our hospital with complaints of lumbago. Based on MRI, bone marrow biopsy, and upper endoscopy, she was diagnosed as having advanced gastric cancer accompanied by bone marrow metastasis and multiple bone metastases. She underwent combination chemotherapycontaining S-1 and docetaxel(TXT). However, during the first course of chemotherapy, she developed Grade 4 neutropenia and sepsis, and her ADL worsened. The anticancer agent doses were reduced drasticallyto 40% of the initial dose from the next course of chemotherapy. She was able to continue treatment without developing severe adverse events, and the disease did not progress for 11 months. However, during the 6 course of chemotherapy, she developed Grade 4 neutropenia and sepsis again, and it became difficult to continue treatment. Subsequent S-1 monotherapywas not efficacious, and she died 17 months after diagnosis. From the view of persistence and efficacy, we believe that low-dose combination chemotherapycontaining S-1 and TXT maybe a suitable regimen for advanced gastric cancer with bone marrow metastasis.

Tumour-infiltrating lymphocytes (TILs)-related genomic signature predicts chemotherapy response in breast cancer.

PURPOSE: The present study evaluated whether morphological-measured stromal and intra-tumour tumour-infiltrating lymphocytes (TILs) levels were associated with gene expression profiles, and whether TILs-associated genomic signature (GS) could be used to predict clinical outcomes and response to therapies in several breast cancer subtypes. METHODS: We retrospectively evaluated haematoxylin eosin (HE)-TILs levels and gene expression profiling data from 40 patients with primary breast cancer and extracted the 22 overexpressed genes in cases with high TILs scores as the TILs-GS. The TILs-GS were compared with breast cancer subtype and were evaluated predictive values for prognosis and response to therapies. RESULTS: Higher TILs-GS expressions were observed for triple-negative and human epidermal growth factor receptor 2 (HER2) positive (+) breast cancers, compared to the luminal types (P < 0.001). With the exception of HER2+, the TILs-GS had no prognostic value in subtypes of breast cancers. The Wilcoxon test revealed significantly different TILs-GS levels between the cases with pathological complete response (pCR) and residual disease after anthracycline and taxane-based neoadjuvant chemotherapy, with the exception of the luminal-low proliferation subtype. In the multivariate analysis, pCR was independently associated with smaller tumour size, higher histological grade, ER negativity, HER2 positivity and higher TILs-GS scores (OR 2.02, 95% CI 1.30-3.14, P = 0.025). CONCLUSIONS: TILs-GS was associated with stromal and intra-tumour TILs levels, as evaluated using HE, which predicted prognosis and chemotherapy response in several breast cancer subtypes. Further studies are needed to perform stratification according to TILs-GS levels and the conventional breast cancer subtypes.

[Breast Cancer Occurring in the Axillary Area - A Case Report].

A 50-year-old woman aware a lump in the right axillary area 5 years ago.She noticed that the lump gradually became bigger, accompanied by redness and gathering of the skin; therefore, she consulted a dermatologist.On receiving the result of skin biopsy, she was referred for a suspected metastatic lesion from breast cancer.The mass was 20mm in diameter, was palpable in the right axillary area, and accompanied by redness of the skin.Ultrasonography revealed 2 irregular-shaped masses in the right axillary area.An FDG/PET study showed some abnormal uptake in the right axillary area, but there were no other primary lesions in any other organs.We performed tumorectomy, and the axillary tumors was histopathologically diagnosed as invasive ductal carcinoma.This case was comprehensively presumed to be accessory breast cancer.In the case of malignant tumor in the axillary area, differential diagnoses are axillary lymph node metastasis of latent breast cancer, ectopic breast cancer, accessory breast cancer, and malignant tumors of skin and its appendages.We presented here a case of carcinoma that was estimated as accessory breast cancer considering clinical, radiological and pathological findings in an integrating manner.

Distinct breast cancer characteristics between screen- and self-detected breast cancers recorded in the Japanese Breast Cancer Registry.

The rate of breast cancer screening for women of all ages in Japan is increasing. However, little is known about the biological differences between screen- and self-detected tumors. We used data from the Japanese Breast Cancer Registry (JBCR), a nationwide registry of newly diagnosed breast cancer cases in Japan, to investigate patients diagnosed between January 1, 2004 and December 31, 2011. We compared the clinicopathological features of tumors and assessed yearly trends regarding the proportion of screen-detected cases during the study period. We found that 31.8 % (65,358/205,544) of cancers were detected by screening. Asymptomatic tumors detected by screening (asymptomatic) were more likely to have favorable prognostic features than those that were self-detected (ductal carcinoma in situ [DCIS]: 19.8 versus 4.1 %, node-negative: 77.0 versus 61.6 %, and estrogen receptor-positive [ER+]: 82.0 versus 72.9 %, respectively). All these findings were statistically significant (p < .001). The proportion of breast cancers detected by screening among all cases increased from 21.7 % in 2004 to 37.1 % in 2011. During the same time period, the proportion of screen-detected DCIS increased from 41.5 to 66.0 % and that of ER+ cancers increased from 23.2 to 39.7 %. This study demonstrated that low-risk tumors, including DCIS, ER+, and lower TNM stage, account for a substantial proportion of clinical screening-detected cancers. The differences in biological characteristics between screen- and self-detected cancers may account in part for the limited efficacy of breast cancer screening programs aimed at improving breast cancer mortality.

Young adult breast cancer patients have a poor prognosis independent of prognostic clinicopathological factors: a study from the Japanese Breast Cancer Registry.

PURPOSE: The aim of this study was to investigate whether young age at onset of breast cancer is an independent prognostic factor in patients from the Japanese Breast Cancer Registry, after adjustment of known clinicopathological prognostic factors. METHODS: Of the 53,670 patients registered between 2004 and 2006 and surveyed after a 5-year follow-up prognosis, 25,898 breast cancer patients (48.3 %), who were obtained prognostic data, were examined. Clinicopathological factors were compared between young adult (YA; <35 years), middle-aged adult (MA; 35-50 years), and older adult (OA; >50 years) patients. Five-year disease-free survival (DFS) and overall survival (OS) rates were studied. RESULTS: YA patients were associated with an advanced TNM stage and aggressive characteristics (e.g. human epidermal growth factor receptor 2 (HER2)-positive or oestrogen receptor (ER)-negative breast cancers) compared to MA and OA patients (P < 0.001). The 5-year DFS and OS rates were 79.4 % and 90.8, 88.5 and 95.0 %, and 87.8 % and 91.6 % for YA, MA, and OA patients, respectively. From the multivariable regression analysis, young age at onset was confirmed as an independent prognostic factor for both DFS (hazard ratio 1.73, 95 % confidence interval 1.42-2.10; P < 0.001) and OS (hazard ratio 1.58, 95 % confidence interval 1.16-2.15; P = 0.004). CONCLUSIONS: Young age at onset is an independent negative prognostic factor in breast cancer. Further studies are required to develop new therapeutic strategies for YA breast cancer patients.

Altered intracellular region of MUC1 and disrupted correlation of polarity-related molecules in breast cancer subtypes.

MUC1 glycoprotein is overexpressed and its intracellular localization altered during breast carcinoma tumorigenesis. The present study aimed to clarify the relationship of cytoplasmic localization of MUC1 with the breast cancer subtype and the correlation of 10 molecules associated with cell polarity in breast cancer subtypes. We immunostained 131 formalin-fixed and paraffin-embedded breast cancer specimens with an anti-MUC1 antibody (MUC1/CORE). For 48 of the 131 tumor specimens, laser-assisted microdissection and real-time quantitative RT-PCR were performed to analyze mRNA levels of MUC1 and 10 molecules, ß-catenin, E-cadherin, claudin 3, claudin 4, claudin 7, RhoA, cdc42, Rac1, Par3 and Par6. Localization of MUC1 protein varied among breast cancer subtypes, that is, both the apical domain and cytoplasm in luminal A-like tumors (P < 0.01) and both the cytoplasm and cell membrane in luminal B-like (growth factor receptor 2 [HER2]+) tumors (P < 0.05), and no expression was found in triple negative tumors (P < 0.001). Estrogen receptor (ER)+ breast cancers showed higher MUC1 mRNA levels than ER- breast cancers (P < 0.01). The incidence of mutual correlations of expression levels between two of the 10 molecules (55 combinations) was 54.5% in normal breast tissue and 38.2% in luminal A-like specimens, 16.4% in luminal B-like (HER2+), 3.6% in HER2 and 18.2% in triple negative specimens. In conclusion, each breast cancer subtype has characteristic cytoplasmic localization patterns of MUC1 and different degrees of disrupted correlation of the expression levels between the 10 examined molecules in comparison with normal breast tissue.

The size of retrieved lymph nodes correlates with the number of retrieved lymph nodes and is an independent prognostic factor in patients with stage II colon cancer.

PURPOSE: In stage II colon cancer, patients with many retrieved lymph nodes (LNs) have been reported to have better oncological outcomes. We tested the hypothesis that the greater number of retrieved LNs is related to a larger LN size. METHODS: The subjects comprised 320 patients with stage II colon cancer who underwent curative resection. All operations were elective and were performed by the same surgeons. The maximum long axis and short axis diameters of LNs were measured on hematoxylin-eosin-stained specimens. RESULTS: A total of 4,744 LNs were evaluated. The number of retrieved LNs was 14.8 ± 10.1 (mean ± SD). The long axis diameter was 4.8 ± 2.6 mm, with a median value of 4.3 mm, a maximum value of 20.4 mm, and a minimum value of 0.6 mm. The corresponding short axis diameters were 3.4 ± 1.7, 3.0, 15.1, and 0.5 mm, respectively. The highest correlation coefficient for the association with the number of LNs was obtained for the maximum value of the long axis diameter (0.59). Multivariate analysis revealed that age, tumor location, pathological T stage, and the maximum long axis diameter were independent prognostic factors. The number of LNs was not a significant factor. Patients with less than 12 LNs and a maximum long axis diameter of less than 10 mm had significantly poorer outcomes (p < 0.001). CONCLUSION: In patients with stage II colon cancer, the maximum long axis diameter of LNs correlated with the number of LNs and was an independent prognostic factor.

Overexpression of PGC1α and accumulation of p62 in apocrine carcinoma of the breast.

Apocrine carcinoma is categorized as a special type of breast carcinoma because of its specific morphological features. To clarify the characteristics of apocrine carcinoma from the point of view of the mitochondrial profile, we conducted a comparative study between apocrine and non-apocrine carcinomas. The expressions of mitochondrial related factors (PGC1α, Nrf1, Nrf2, mtTFA and COX4) were examined in a testing set of breast cancer tissue. Apocrine carcinomas showed a clear tendency towards higher mRNA expression levels of PGC1α than non-apocrine carcinomas. The expression of the selected factor, PGC1α, as well as that of p62 was further examined. The results revealed that apocrine carcinomas showed a higher immunohistochemical positivity rate for PGC1α (21.3% vs. 3.2%; P = 0.008), and that the mRNA expression level of PGC1α was significantly higher in apocrine carcinoma than in non-apocrine carcinoma (P = 0.007). The immunohistochemical positivity rate for p62 protein was also higher in apocrine carcinomas (44.7% vs. 21.0%; P = 0.015), although no significant difference in the p62 mRNA expression level was detected between the two types of carcinoma (P = 0.633). In conclusion, this study revealed that apocrine carcinoma overexpressed PGC1α contributing to mitochondrial biogenesis, and also p62 protein accumulation.

AKR1C3-negative high-risk metastatic castration-sensitive prostate cancer has long-term response to first-line treatment with abiraterone: Four case reports.

We experienced four cases of high-risk metastatic castration-sensitive prostate cancer (mCSPC) in which first-line treatment with abiraterone showed a sustained long-term response of over 5 years. We conducted immunohistochemical staining of aldo-keto reductase family 1 member C3 (AKR1C3) expression, which associate with poor prognosis of metastatic castration-resistant prostate cancer (mCRPC), and all prostate cancer tissue from four cases showed negative. These results suggested that AKR1C3-negative high-risk mCSPC cases may respond well to first-line treatment with abiraterone. This is the first report describing association of high-risk mCSPC and negative AKR1C3.

Next-generation sequencing of primary testicular lymphoma and relapse in the glans penis after prophylactic radiation therapy: a rare case report.

BACKGROUND: Primary testicular lymphoma (PTL) is relatively rare. The contralateral testis is a common site of PTL relapse; therefore, once complete remission is achieved, radiation therapy (RT) is administered to the contralateral testis to prevent relapse. CASE PRESENTATION: A 76-year-old man was diagnosed with PTL and received RT as described above. However, despite achieving and maintaining complete remission, a mass diagnosed as diffuse large B-cell lymphoma by tissue biopsy developed in the glans penis 6.5 years after prophylactic RT. We investigated whether the glans penile lymphoma was PTL relapse or a new malignancy by genomic analysis using next-generation sequencing of DNA extracted from two histopathological specimens. CONCLUSIONS: We found the same variant allele fraction in four somatic genes (MYD88, IL7R, BLNK, and FLT3) at similar frequencies, indicating that the glans penile lymphoma had the same origin as the PTL. To the best of our knowledge, this is the first case report of PTL relapse in the glans penis.

A comparison of diagnostic utility of new endoscopic scraper combined cell block method and conventional brush catheter for biliary tract cancer.

Background/Aims: The sensitivities of endoscopic trans-papillary pathologic diagnosis of biliary tract cancer (BTC) are unsatisfactory. Recently, the diagnostic utility of the endoscopic scraper device, Trefle for biliary stricture has been reported. The Trefle can be guided to the target biliary stricture over the guidewire and is as easy to use as the conventional brush catheter (CBC). This study evaluated the efficacy and safety of Trefle-assisted tissue acquisition combined cell block method and CBC cytology for biliary strictures due to BTCs. Methods: We retrospectively reviewed consecutive patients with biliary strictures in whom CBC cytology or Trefle-assisted tissue acquisition under endoscopic retrograde cholangiopancreatography was performed for suspected BTCs from January 2015 to June 2022 at our institution. Results: 173 patients (CBC group; n = 55, Trefle group; n = 118) were enrolled in this study. The sensitivity, specificity, and accuracy of CBC cytology for BTC were 68.3%/100%/76.4%. On the other hand, the sensitivity, specificity, and accuracy of Trefle-assisted tissue acquisition for BTC were 93.7%/95.7%/94.1%, showing superior sensitivity (p < 0.001) and accuracy (p = 0.002) compared to that of CBC. Conclusions: Compared to CBC cytology, Trefle-assisted tissue acquisition has superior diagnostic performance while maintaining procedural simplicity and is considered useful for diagnosing malignant biliary stricture.

Correlation between pathology and quantitative ultrasonographic evaluation of pancreatic fat with ultrasonographic classification.

PURPOSE: No studies of the relationship between grayscale sonographic findings and pancreatic fat content have been reported to date. This study aimed to investigate the correlation between echogenicity and fat content of resected specimens using quantitative analysis. METHODS: Forty-two consecutive patients who underwent pancreatoduodenectomy or distal pancreatectomy for pancreatic tumors were enrolled in this study. Ultrasonographic images were compared with quantitative pathological analysis. Subjective evaluation of echogenicity was classified as hypoechoic, isoechoic, hyperechoic, and super hyperechoic. The total and intralobular fat areas were measured. RESULTS: The mean, median, modal, minimum, and maximum ultrasound gray values correlated with the proportion of total fat area (r = 0.349; 0.357, 0.486, 0.466, and 0.347; p = 0.024, 0.020, 0.014, 0.019, and 0.089, respectively), but did not correlate with the proportion of intralobular fat area. Subjective classification was correlated with median gray value (p < 0.001), intralobular fat area (p = 0.118), and total fat area (p = 0.011). Cases were classified as hypoechoic (n = 3), isoechoic (n = 7), hyperechoic (n = 30), and super hyperechoic (n = 2). The subjective classification was correlated with the median gray value (p < 0.001) and total fat area (p = 0.005), and not correlated with the intralobular fat area (p = 0.118). Hyperechoic or super hyperechoic pancreatic parenchyma contains over 19.7% fat. Computed tomography values correlated with the proportion of intralobular fat area (r = - 0.479, p = 0.004) and total fat area (r = - 0.541, p < 0.001). CONCLUSION: Echogenicity classified based on subjective evaluation and image analysis were correlated with the proportion of fat in the pancreas.

Immunohistochemical and molecular profiles of heterogeneous components of metaplastic breast cancer: a squamous cell carcinomatous component was distinct from a spindle cell carcinomatous component.

Metaplastic breast carcinoma (MBC), a category of breast cancer, includes different histological types, which are occasionally mixed and heterogeneous. Considering the heterogeneity of cancer cells in a tumour mass has become highly significant, not only from a biological aspect but also for clinical management of recurrence. This study aimed to analyse the immunohistochemical and molecular profiles of each MBC component of a tumour mass. Twenty-five MBC tumours were histologically evaluated, and the most frequent MBC component (c) was squamous cell carcinoma (SCC), followed by spindle cell carcinoma (SpCC). A total of 69 components of MBC and non-MBC in formalin-fixed paraffin-embedded sections were examined for 7 markers by immunohistochemistry. SCC(c) were significantly PTEN negative and CK14 positive, and SpCC(c) were significantly E-cadherin negative and vimentin positive. Multivariate analyses revealed that immunohistochemical profiles of normal/intraductal (IC)(c), no special type (NST)(c), and MBC(c) differed; moreover, SCC(c) and SpCC(c) were distinctly grouped. PTEN gene mutation was detected only in SCC(c) (2/7), but not in SpCC(c). Next-generation sequence analyses for 2 cases with tumours containing SCC(c) demonstrated that PTEN gene mutation increased progressively from IC(c) to NST(c) to SCC(c). In conclusion, the immunohistochemical and molecular profiles of the SCC(c) of MBC are distinct from those of the SpCC(c).

Different effects of crizotinib treatment in two non-small cell lung cancer patients with SDC4::ROS1 fusion variants.

The possibility of stratifying patients according to differences in ROS proto-oncogene 1 (ROS1) fusion partners has been discussed. This study aimed to clarify the clinicopathological differences between two SDC4::ROS1 positive NSCLC cases who had different responses to crizotinib. Cytology and pathology samples from two NSCLC cases with SDC4::ROS1 who were diagnosed and treated with crizotinib at Nihon University Itabashi Hospital were obtained. Case 1 has been well-controlled with crizotinib for over 5 years, but case 2 was worse and overall survival was 19 months. Sequencing analysis of ROS1 fusion genes was performed by reverse-transcription-PCR and Sanger's sequencing methods. In addition, thyroid transcription factor (TTF)-1, ROS-1, Ki67, and phosphorylated extracellular signal-regulated kinase (pERK)1/2 expression were investigated using immunohistochemistry. Sequencing analysis showed SDC4 exon2::ROS1 exon 32 (exon33 deleted) in case 1, and coexistence of SDC4 exon2::ROS1 exon 34 and SDC4 exon2::ROS1 exon35 in case 2. The Ki67 index was not different, but ROS1 and pERK1/2 expression levels tended to be higher in the tumor cells of case 2 than in case 1. Therapeutic response to crizotinib and patients' prognosis in ROS1 rearranged NSCLC may be related to the activation of ROS1 signaling, depending on ROS1 and pERK1/2 overexpression status, even if the ROS1 fusion partner is the same.

Brain metastasis in a patient with BRCA2-mutated treatment-related neuroendocrine prostate carcinoma and long-term response to radiotherapy and Olaparib: A case report and literature review.

BACKGROUND: A new subtype of prostate cancer called treatment-related neuroendocrine prostate carcinoma (t-NEPC) was added to the revised World Health Organization classification of prostate cancer in 2022. t-NEPC cases are increasing, and there is no established standard treatment. METHODS: A 49-year-old male patient was referred to our department for dysuria. A rectal examination and a prostate biopsy revealed stony hardness and prostate adenocarcinoma, respectively. Imaging studies confirmed the presence of multiple bone and lymph node metastases. The patient was started on upfront treatment with androgen deprivation therapy and an androgen receptor signaling inhibitor, which resulted in a significant (>90%) decrease in prostate-specific antigen (PSA) levels. The patient experienced postrenal failure 6 months later, attributable to local disease progression. Concurrently, there was an elevation in neuron-specific enolase (NSE) levels and an enlargement of pelvic lymph node metastases, without PSA progression. RESULTS: Biopsy specimen for cancer genome profiling revealed deletion of BRCA 2 and PTEN, AR amplification, and the presence of the TMPRSS2-ERG fusion gene. Based on increased NSE and BRCA2 mutations, a diagnosis of t-NEPC with BRCA2 mutation was eventually made. The patient received docetaxel chemotherapy and pelvic radiotherapy. Subsequently, he was treated with olaparib. His NSE levels decreased, and he achieved a complete response (CR). However, 18 months following the olaparib administration, brain metastases appeared despite the absence of pelvic tumor relapse, and the patient's PSA levels remained low. Consequently, the patient underwent resection of the brain metastases using gamma knife and whole-brain radiotherapy but died approximately 3 months later. CONCLUSION SUBSECTIONS: Platinum-based chemotherapy is often administered for the treatment of t-NEPC, but there are few reports on the effectiveness of olaparib in patients with BRCA2 mutations. In a literature review, this case demonstrated the longest duration of effectiveness with olaparib alone without platinum-based chemotherapy. Additionally, the occurrence of relatively rare, fatal brain metastases in prostate cancer after a long period of CR suggests the necessity of regular brain imaging examinations.