Laparoscopy-Assisted Restorative Proctocolectomy with Ileal Pouch-Anal Anastomosis in Middle Colic Artery Ligation Immediately before Specimen Removal.

Introduction: Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the surgical procedure for ulcerative colitis (UC). Intestinal ischemia may occur if the main blood vessels are ligated at an early stage of this surgery. Considering that the blood flow in the large intestine can be maintained by preserving the middle colic artery, we have used a new IPAA method: ligating the middle colic artery immediately before removal of the specimens ("M-method"). Here, we evaluated the M-method's clinical outcomes. Methods: Between April 2009 and December 2021, 13 patients underwent a laparoscopy-assisted IPAA procedure at our institution. The conventional method was used for 6 patients, and the M-method was used for the other 7 patients. We retrospectively analyzed the cases' clinical notes. Results: The M-method's rate of postoperative complications (Clavien-Dindo classification grade II or more) was significantly lower than that of the conventional method (14.2% vs. 83.3%). The M-method group's postoperative stay period was also significantly shorter (average 16.4 days vs. 55.5). There were significant differences in the albumin value and the ratio of the modified GPS score 1 or 2 on the 7th postoperative day between the M- and conventional methods (average 3.15 vs. 2.5, average 4/7 vs. 6/6). However, it is necessary to consider the small number of cases and the uncontrolled historical comparison. Conclusion: Late ligation of the middle colic artery may be beneficial for patients' post-surgery recovery and can be recommended for IPAAs in UC patients.

Ceramide synthase CERS4 gene downregulation is associated with KRAS mutation in colorectal cancer.

Ceramide, the central molecule in sphingolipid synthesis, is a bioactive lipid that serves as a regulatory molecule in the anti-inflammatory responses, apoptosis, programmed necrosis, autophagy, and cell motility of cancer cells. In particular, the authors have reported differences in sphingolipid content in colorectal cancer tissues. The associations among genetic mutations, clinicopathological factors, and sphingolipid metabolism in colorectal cancer (CRC) have not been investigated. The objective of this study is to investigate the association between genes associated with sphingolipid metabolism, genetic variations in colorectal cancer (CRC), and clinicopathological factors in CRC patients. We enrolled 82 consecutive patients with stage I-IV CRC who underwent tumor resection at a single institution in 2019-2021. We measured the expression levels of genes related to sphingolipid metabolism and examined the relationships between CRC gene mutations and the clinicopathological data of each individual patient. The relationship between CRC gene mutations and expression levels of ceramide synthase (CERS), N-acylsphingosine amidohydrolase (ASAH), and alkaline ceramidase (ACER) genes involved in sphingolipid metabolism was examined CRES4 expression was significantly lower in the CRC KRAS gene mutation group (p = 0.004); vascular invasion was more common in colorectal cancer patients with high CERS4 expression (p = 0.0057). By examining the correlation between sphingolipid gene expression and clinical factors, we were able to identify cancer types in which sphingolipid metabolism is particularly relevant. CERS4 expression was significantly reduced in KRAS mutant CRC. Moreover, CRC with decreased CERS4 showed significantly more frequent venous invasion.

The first case of laparoscopic surgery for cecal cancer occurring in a blind loop.

Cancer occurrence in a blind loop is extremely rare. An 86-year-old Japanese woman underwent colonoscopy for tarry stools and weight loss; it revealed a bypass of the transverse colon and small intestine, cecal cancer, and a polyp. She had suffered from acute appendicitis and had undergone two surgeries at age 25: an appendectomy and then a bypass surgery between the transverse colon and the small intestine. We performed a laparoscopy-assisted ileocecal resection for the cancer and polyp in the blind loop with an end-to-side instrumental anastomosis. The pathological examination demonstrated that the cancer was medullary carcinoma (T2, N0, M0, Stage I) and the polyp was tubular adenoma. Two months have passed since the patient's discharge, and she is free of abdominal complaints. Our literature search identified 10 cases of cancer in a blind loop. Laparoscopy-assisted surgery may be possible in patients who have undergone blind-loop surgery.

Prognostic Value of KRAS Exon-specific Mutations in Patients With Colorectal Cancer.

BACKGROUND/AIM: The clinical significance of many RAS-family mutations in colorectal cancer (CRC) remains unclear. The purpose of this study was to investigate the relationship of RAS mutations on an exon basis (i.e., mutations in KRAS exons 2, 3, and 4 and in NRAS) with clinicopathological features and prognosis in CRC. PATIENTS AND METHODS: We performed a retrospective cohort study of the medical records and frozen tissue samples of 268 consecutive patients with stage I-III CRC who underwent curative resection at a single institution between 2014 and 2018. RESULTS: The RAS mutation rate was significantly associated with age and histology. Patients with KRAS exon 2 mutations exhibited shorter recurrence-free survival compared to those with KRAS wild-type, KRAS exon 3 mutations, KRAS exon 4 mutations, and NRAS mutations (73.0% vs. 85.5%, 86.7%, 85.7%; p=0.031). Age and histology were independent risk factors for RAS mutations. RAS mutations were independent prognostic factors with respect to recurrence-free survival in patients with stage I-III CRC. CONCLUSION: In stage I-III CRC patients, KRAS exon 2 mutations had the worst prognosis, whereas KRAS wild type, exon 3 mutations, exon 4 mutations, and NRAS mutations had better prognoses.

Effect of Biologics on the Risk of Advanced-Stage Inflammatory Bowel Disease-Associated Intestinal Cancer: A Nationwide Study.

INTRODUCTION: The aim of this study was to evaluate the effect of biologics on the risk of advanced-stage inflammatory bowel disease (IBD)-associated intestinal cancer from a nationwide multicenter data set. METHODS: The medical records of patients with Crohn's disease (CD) and ulcerative colitis (UC) diagnosed with IBD-associated intestinal neoplasia (dysplasia or cancer) from 1983 to 2020 were included in this study. Therapeutic agents were classified into 3 types: biologics, 5-aminosalicylic acid, and immunomodulators. The pathological cancer stage was compared based on the drug used in both patients with CD and UC. RESULTS: In total, 1,042 patients (214 CD and 828 UC patients) were included. None of the drugs were significantly associated with cancer stage in the patients with CD. In the patients with UC, an advanced cancer stage was significantly associated with less use of biologics (early stage: 7.7% vs advanced stage: 2.0%, P < 0.001), 5-aminosalicylic acid, and immunomodulators. Biologic use was associated with a lower incidence of advanced-stage cancer in patients diagnosed by regular surveillance (biologics [-] 24.5% vs [+] 9.1%, P = 0.043), but this was not the case for the other drugs. Multivariate analysis showed that biologic use was significantly associated with a lower risk of advanced-stage disease (odds ratio = 0.111 [95% confidence interval, 0.034-0.356], P < 0.001). DISCUSSION: Biologic use was associated with a lower risk of advanced IBD-associated cancer in patients with UC but not with CD. The mechanism of cancer progression between UC and CD may be different and needs to be further investigated.

Neural correlates of category learning in monkey inferior temporal cortex.

We trained two monkeys implanted with multi-electrode arrays to categorize natural images of cats and dogs, in order to observe changes in neural activity related to category learning. We recorded neural activity from area TE, which is required for normal learning of visual categories based on perceptual similarity. Neural activity during a passive viewing task was compared pre- and post-training. After the category training, the accuracy of abstract category decoding improved. Specifically, the proportion of single units with category selectivity increased, and units sustained their category-specific responses for longer. Visual category learning thus appears to enhance category separability in area TE by driving changes in the stimulus selectivity of individual neurons and by recruiting more units to the active network.

Pharmacological inactivation of the primate posterior insular/secondary somatosensory cortices attenuates thermal hyperalgesia.

BACKGROUND: We previously established a macaque model of central post-stroke pain (CPSP) and confirmed the involvement of increased activity of the posterior insular cortex (PIC) and secondary somatosensory cortex (SII) to somatosensory stimuli in mechanical allodynia by a combination of imaging techniques with local pharmacological inactivation. However, it is unclear whether the same intervention would be effective for thermal hyperalgesia. Therefore, using the macaque model, we examined behavioural responses to thermal stimuli following pharmacological inactivation of the PIC/SII. METHODS: Two CPSP model macaques were established based on collagenase-induced unilateral hemorrhagic lesions in the ventral posterolateral nucleus of the thalamus. To evaluate pain perception, withdrawal latencies to thermal stimuli of 37, 45, 50, 52, and 55 °C to hands were measured. Several weeks after the lesion induction, pharmacological inactivation of the PIC/SII by microinjection of muscimol was performed. The effect of inactivation on withdrawal latency was assessed by comparison with withdrawal latency after vehicle injection. RESULTS: Several weeks after induction of the thalamic lesions, both macaques demonstrated a reduction in withdrawal latencies to thermal stimulation (<50 °C) on the contralesional hand, indicating the occurrence of thermal hyperalgesia. When the PIC/SII were inactivated by muscimol, the withdrawal latencies to thermal stimuli of 50 and 52 °C were significantly increased compared to those after vehicle injection. CONCLUSIONS: Our data emphasize that increased activity in the PIC/SII after appearance of thalamic lesions can contribute to abnormal pain of multiple modalities, and the modulation of PIC/SII activity may be a therapeutic approach for thermal hyperalgesia. SIGNIFICANCE: CPSP is caused by stroke lesions in the sensory system and characterized by mechanical allodynia or thermal hyperalgesia. Inactivation of the PIC/SII has an analgesic effect on mechanical allodynia; however, it is not clear whether the same intervention could reduce thermal hyperalgesia. Here, using the macaque model, we demonstrated that inactivation of these cortices reduces hypersensitivity to thermal stimuli. This result emphasizes that increased PIC/SII activity can contribute to abnormal pain of multiple modalities.

Active Middle Ear Implant in a Patient with Neurofibromatosis Type 1 and Multiple Calvarial Defects: A Case Report.

Bony abnormalities, including sphenoid dysplasia and calvarial defects, are well recognized in patients with neurofibromatosis type 1. However, having multiple calvarial defects is rare. We present a case of a 35-year-old Japanese male patient who was referred to our hospital because of hearing loss. He was diagnosed with neurofibromatosis type 1 during early childhood. Otoscopic examination revealed a protrusion from the anterior wall of the external auditory canal that obstructed the external auditory canal. Computed tomography findings revealed multiple defects and an uneven skull surface. Large bony defects of the anterior wall of the external auditory canal were also identified bilaterally. Conductive hearing loss was caused by temporomandibular joint herniation that was obstructing the external auditory canal in both ears. An active middle ear implant was implanted in the right ear. A floating mass transducer was placed into the round window niche using a round window coupler. The active middle ear implant improved postoperative audiometric thresholds to approximately 35 dB across all frequencies. No complications occurred for up to 30 months after the operation. An active middle ear implant is a feasible and valuable option for patients with neurofibromatosis type 1 and conductive hearing loss due to multiple skull defects that result in temporomandibular joint herniation.

The preoperative geriatric nutritional risk index (GNRI) is an independent prognostic factor in elderly patients underwent curative resection for colorectal cancer.

The world is becoming longer-lived, and the number of elderly colorectal cancer patients is increasing. It is very important to identify simple and inexpensive postoperative predictors in elderly colorectal cancer patients. The geriatric nutritional risk index (GNRI) is a marker of systemic nutrition and is associated with poor survival in various kinds of cancers. A few reports have investigated recurrence factors using preoperative GNRI with CRC (colorectal cancer) patients. This study aimed to investigate whether preoperative GNRI is associated with recurrence-free survival (RFS) and overall survival (OS) in elderly patients with CRC. This study retrospectively enrolled 259 patients with Stage I-III CRC who were more than 65 years old and underwent curative surgery at a single institution in 2012-2017. We classified them into low GNRI (RFS: ≤ 90.5, OS ≤ 101.1) group and high GNRI (RFS: > 90.5, OS > 101.1) group. Multivariable analyses showed low GNRI group was an independent risk factor for 3-year RFS (P = 0.006) and OS (P = 0.001) in the patients with CRC. Kaplan-Meier analysis showed 3-year RFS and 3-year OS were significantly worse in the low GNRI group than in high GNRI group (p = 0.001, 0.0037). A low-preoperative GNRI was significantly associated with a poor prognosis in elderly CRC patients.

Accuracy of preoperative staging of gastric stump cancer.

BACKGROUND: In this study, the accuracy of preoperative staging for gastric stump cancer, which has not been thoroughly investigated since the condition is rare, was investigated using computed tomography and gastroscopic imaging. METHODS: Between February 1994 and April 2018, 49 patients with gastric stump cancer, following subtotal or total gastrectomy, were reviewed retrospectively. Preoperative diagnoses of clinical T and clinical N categories were compared with post-operative pathological diagnoses (pT and pN categories). Positive predictive values, accuracy, sensitivity and specificity were also evaluated. RESULTS: The overall accuracy of T staging was 40.8%. The positive predictive value for cT3/T4 was 96.3%, whereas the positive predictive value for cT1/T2 was 72.7%. The overall accuracy for N staging was 61.2%. The positive predictive value of lymph node positive patients was 73.3%. The positive predictive value and sensitivity of over stage II were 96.6% and 84.8%, respectively. CONCLUSIONS: The accuracy of preoperative diagnosis using both computed tomography and gastroscopy imaging may be feasible for T3/T4 advanced gastric stump cancer, whereas diagnosing T1/2 gastric stump cancer must be carefully considered due to high misdiagnosis rates, relating to depth.

Predicting Overall Survival Using Preoperative Nutritional and Inflammation Status for Colorectal Cancer.

AIM: It has been shown that nutritional status and inflammation correlate with survival in patients with various cancer types. In this study, we evaluated several kinds of nutritional and inflammation parameters in preoperative blood samples and constructed new risk model predicting survival in patients with colorectal cancer. PATIENTS AND METHODS: We retrospectively examined 286 patients with stage I-III colorectal cancer who had undergone curative resection at Teikyo University Hospital. The association between overall survival (OS) and nutritional status and inflammation factors were examined using Kaplan-Meier curves and log-rank tests. RESULTS: Serum albumin, cholesterol and C-reactive protein concentration, neutrophil count and platelet count were shown to be correlated with OS. We constructed a new risk model (nutrition inflammation status, NIS) using these factors, and compared it with other nutrition and inflammation models. CONCLUSION: NIS was useful as a new model for predicting OS in patients undergoing curative resection for colorectal cancer, compared with known models.

Impact of subdivision of pathological stage I colorectal cancer.

AIM: Stage II-IV colorectal cancers are subdivided according to TNM categories. However, stage I cases are a single category, despite the inclusion of both T1 and T2 cases, which may have different outcomes. The aim of this study was to evaluate the usefulness of subdividing stage I colorectal cancers by T category. METHODS: From 1984 to 2015, 844 patients with stage I colorectal cancer (T1: 446, T2: 398) underwent colorectal resection with lymph node dissection at three hospitals. The long-term survival and recurrence rates were compared between T1 and T2. A Cox regression analysis was used to evaluate the risk factors associated with cancer recurrence. RESULTS: A comparison of the T1 and T2 groups revealed significant differences in 5-year overall (95.9% vs 91.4%, P = .008), recurrence-free (94.8% vs 87.1%, P = .0007), and cancer-specific survival (97.6% vs 93.6%, P = .004), and in the overall (2.5% vs 6.8%, P = .003), local (0.2% vs 1.5%, P = .04), and lymph node recurrence rates (0.2% vs 1.5%, P = .04). All local and lymph node recurrences were associated with lower rectal cancer, and this difference was significant. The Cox multivariate analysis identified male sex (P = .01, hazard ratio: 4.00, 95% confidence interval: 1.38-11.55), T2 (P = .02, hazard ratio: 2.98, 95% confidence interval: 1.17-7.60), and venous invasion (P = .03, hazard ratio: 2.38, 95% confidence interval: 1.12-5.10) as risk factors for recurrence. CONCLUSIONS: The subdivision of stage I colorectal cancer according to T category clearly reflected the long-term outcomes.

Structural Plastic Changes of Cortical Gray Matter Revealed by Voxel-Based Morphometry and Histological Analyses in a Monkey Model of Central Post-Stroke Pain.

Central post-stroke pain (CPSP) is a chronic pain caused by stroke lesions of somatosensory pathways. Several brain imaging studies among patients with CPSP demonstrate that the pathophysiological mechanism underlying this condition is the maladaptive plasticity of pain-related brain regions. However, the temporal profile of the regional plastic changes, as suggested by brain imaging of CPSP patients, as well as their cellular basis, is unknown. To investigate these issues, we performed voxel-based morphometry (VBM) using T1-weighted magnetic resonance imaging and immunohistochemical analysis with our established CPSP monkey model. From 8 weeks after a hemorrhagic lesion to the unilateral ventral posterolateral nucleus of the thalamus, the monkeys exhibited significant behavioral changes that were interpreted as reflecting allodynia. The present VBM results revealed a decrease in gray matter volume in the pain-related areas after several weeks following the lesion. Furthermore, immunohistochemical staining in the ipsilesional posterior insular cortex (ipsi-PIC) and secondary somatosensory cortex (ipsi-SII), where the significant reduction in gray matter volume was observed in the VBM result, displayed a significant reduction in both excitatory and inhibitory synaptic terminals compared to intact monkeys. Our results suggest that progressive changes in neuronal morphology, including synaptic loss in the ipsi-PIC/SII, are involved in theCPSP.

The robust performance of carcinoembryonic antigen levels after adjuvant chemotherapy for the recurrence risk stratification in patients with colorectal cancer.

BACKGROUND AND OBJECTIVES: Most guidelines of colorectal cancers (CRCs) recommend evaluating the serum carcinoembryonic antigen (CEA) level during postoperative surveillance to detect tumor recurrence, which originates from postsurgery residual tumor cells. We hypothesized that the postadjuvant chemotherapy CEA level may be the most accurate biomarker to predict tumor recurrence, and we evaluated the prognostic significance of the postadjuvant chemotherapy CEA level in patients with stage II and III CRCs. PATIENTS AND METHODS: We retrospectively analyzed the cases of 150 Stage II-III CRC patients who had undergone curative surgery and adjuvant chemotherapy. Preoperative, postoperative, and postadjuvant chemotherapy CEA levels were evaluated, and their associations with recurrence-free survival (RFS) were assessed. RESULTS: The Kaplan-Meier curves showed that a high preoperative CEA level, high postoperative CEA, and high postadjuvant chemotherapy CEA were associated with poor RFS (p = .001, .0001, and .001, respectively). The multivariate analysis demonstrated that high postadjuvant chemotherapy CEA was an independent factor for poor RFS (HR 2.55, 95% confidence interval: 1.08-6.05, p = .033), whereas high preoperative and postoperative CEA levels were not. CONCLUSIONS: The serum levels of postadjuvant chemotherapy CEA were a strong prognostic biomarker in patients with Stage II-III CRCs who had undergone surgery followed by adjuvant chemotherapy.

Very long-chain fatty acids are accumulated in triacylglycerol and nonesterified forms in colorectal cancer tissues.

Colorectal cancer (CRC) is a major cancer, and its precise diagnosis is especially important for the development of effective therapeutics. In a series of metabolome analyses, the levels of very long chain fatty acids (VLCFA) were shown to be elevated in CRC tissues, although the endogenous form of VLCFA has not been fully elucidated. In this study we analyzed the amount of nonesterified fatty acids, acyl-CoA species, phospholipids and neutral lipids such as cholesterylesters using liquid-chromatography-mass spectrometry. Here we showed that VLCFA were accumulated in triacylglycerol (TAG) and nonesterified forms in CRC tissues. The levels of TAG species harboring a VLCFA moiety (VLCFA-TAG) were significantly correlated with that of nonesterified VLCFA. We also showed that the expression level of elongation of very long-chain fatty acids protein 1 (ELOVL1) is increased in CRC tissues, and the inhibition of ELOVL1 decreased the levels of VLCFA-TAG and nonesterified VLCFA in CRC cell lines. Our results suggest that the upregulation of ELOVL1 contributes to the accumulation of VLCFA-TAG and nonesterified VLCFA in CRC tissues.

Impact of Colon Cancer Location on the Prognostic Significance of Nutritional Indexes and Inflammatory Markers.

BACKGROUND/AIM: The prognosis of colorectal cancer is reported to differ depending on the tumor site, and clinical differences depending on the site of occurrence have gained attention. The aim was to compare nutrition index and inflammatory markers according to the site of colon cancer. PATIENTS AND METHODS: We retrospectively analyzed 272 cases of stage I-III colon cancer (55% males, 45% females). The clinical characteristics, nutrition index and inflammatory markers were compared between patients with right colon cancer (RCC, n=119) and those with left colon cancer (LCC, n=153), and the relapse-free survival was then compared. RESULTS: RCC was associated with older age (p=0.03), female gender (p=0.003), higher T stage (p=0.01), elevated platelet/lymphocyte ratio (PLR) (p=0.009), and elevated CONUT score (p=0.028). The prognostic values differed between RCC and LCC (RCC: CONUT score, p=0.04, LCC: PLR, p=0.02). CONCLUSION: RCC was associated with an elevated CONUT score and PLR. In RCC, the CONUT score was an independent recurrence factor, and in LCC, the PLR was an independent recurrence factor.

Concurrent epithelioid hemangioma and diffuse cavernous hemangioma in the rectum clinically mimicking a malignant tumor: a case report.

Epithelioid hemangioma is a rare benign vascular tumor that consists of capillary-sized vessels lined by epithelioid endothelial cells. Diffuse cavernous hemangioma is a congenital benign vascular neoplasm consisting of increased dilated vessels. We report a case of epithelioid hemangioma and diffuse cavernous hemangioma that co-occurred in the rectum. To our knowledge, this is the first report in which two rare vascular lesions coexisted. Because both epithelioid hemangioma and diffuse cavernous hemangioma are often clinically confounded by malignant tumors, differentiating these benign lesions from other possible malignant tumors is significant.

Impact of Fluoropyrimidine and Oxaliplatin-based Chemoradiotherapy in Patients With Locally Advanced Rectal Cancer.

BACKGROUND/AIM: To evaluate the benefits of the addition of oxaliplatin (OX) to fluoropyrimidine (FP)-based neoadjuvant chemoradiotherapy (CRT) for patients with locally advanced rectal cancers (LARCs). PATIENTS AND METHODS: We performed retrospective analyses comparing the pathological complete response (pCR) rate, overall survival (OS), recurrence-free survival (RFS), and local recurrence-free survival (LRFS) between FP-based and FP+OX-based CRT groups and for patients who had completed the CRT. RESULTS: One hundred patients were included in the analyses: the pCR rate, OS, RFS, and LRFS were similar between these groups. The FP+OX group showed significantly more frequent incompleteness of the CRT compared to the FP group (p=0.049). Among the patients who had completed the CRT, the FP+OX group demonstrated significantly improved LRFS compared to the FP group (p=0.048). CONCLUSION: The addition of OX to an FP regimen in neoadjuvant CRT for LARC may reduce local recurrence in patients who have achieved good compliance to CRT.

Proposal for a post-operative surveillance strategy for stage I colorectal cancer patients based on a novel recurrence risk stratification: a multicenter retrospective study.

BACKGROUND: The recurrent risk of stage I colorectal cancer (CRC) is not clear, and the data regarding appropriate post-operative surveillance schedules in stage I CRC are scarce. OBJECTIVES: We aimed to stratify stage I CRC based on the recurrence risk and evaluate optimal post-operative surveillance durations based on this stratification. METHODS: We retrospectively analyzed the cases of 6607 stage I CRC patients from 24 institutions. To assess the patients' clinicopathological factors that impact recurrence-free survival (RFS), we performed univariate and multivariate analyses using Cox proportional hazards models. We divided the patients into classes based on their numbers of factors that were associated with poor RFI in the multivariate analysis. RESULTS: Recurrence occurred in 3.9% patients. The multivariate analysis revealed the independent factors for poor RFS: rectal cancer, T2 depth, presence of lymphatic invasion, high level of pre-operative carcinoembryonic antigen, and absence of D2-3 lymphadenectomy. We also divided the patients into three classes based on their numbers of these risk factors; the 3-year and 5-year RFS rates were 99.3% and 99.1% in the no-risk patients, 97.4% and 96.5% in the patients with 1-2 risks, and 92.1% and 90.0% in the patients with 3-5 risks, respectively. In the patients with no risk and in the patients with 1-2 risks after 3 years post-surgery, ≤ 1% recurrence occurred. Thus, post-operative surveillance may be omitted in these populations. CONCLUSIONS: Our new classification properly stratified the recurrence risks of stage I CRC patients, and may help reduce unnecessary post-operative surveillance.

Nationwide survey of middle ear cholesteatoma surgery cases in Japan: Results from the Japan Otological society registry using the JOS staging and classification system.

OBJECTIVE: This study was aimed to determine the characteristics of middle ear cholesteatoma and to investigate short-term outcomes regarding the rates of residual and recurrent cholesteatoma and the postoperative hearing results in Japan, via a nationwide survey using staging and classification criteria for middle ear cholesteatoma, as proposed by the Japan Otological Society (JOS). METHODS: The first-round survey was conducted in 2016. The target was patients with middle ear cholesteatoma who were surgically treated in Japan between January and December 2015. Medical information on the patients was anonymized. The questionnaire entries were age, sex, cholesteatoma classification and stage, preoperative hearing level, mastoid development, status of the stapes, and surgical method. There were a total of 1,787 registered patients from 74 facilities from all over Japan. The second survey was conducted in January 2018 and received 1,456 responses from 49 facilities in Japan. Of the 1,456 cases, 1,060 were conducted in the postoperative hearing survey and 1,084 in the residual recurrence survey. RESULTS: The most common cholesteatoma type was pars flaccida cholesteatoma (63.3%), followed by pars tensa cholesteatoma (13.0%), congenital cholesteatoma (12.9%), and cholesteatoma secondary to chronic tensa perforation (5.6%). Cholesteatoma of uncertain origin accounted for 5.0% (90 cases). Stage II was predominant in pars flaccida and pars tensa cholesteatoma, which frequently involves the mastoid, whereas about half of cases of cholesteatoma secondary to chronic tensa perforation and congenital cholesteatoma were classified as stage I. One hundred fifty-two of 1,084 cases (14.0%) had recurrent cholesteatoma, residual cholesteatoma, or both following first surgeries. The postoperative rates of hearing success rate was 63.3%. CONCLUSION: We were able to clarify not only the current epidemiological status of middle ear cholesteatoma but also the current trends of cholesteatoma surgery in Japan. The development of a staging system by the JOS Committee serving an epidemiological database for international or time-dependent comparison. It is possible to use this staging system with reasonable reliability.