Predictors of 1-year mortality after gastrectomy for gastric cancer.

PURPOSE: One-year mortality is important for referrals to specialist palliative care or advance care planning (ACP). This helps optimize comfort for those who cannot be cured or have a lower life expectancy. Few studies have investigated the risk factors for 1-year mortality after gastrectomy for gastric cancer (GC). METHODS: A total of 1415 patients with gastric cancer (stages I-IV) who underwent gastrectomy between 2005 and 2020 were included. The patients were randomly assigned to the investigation group (n = 850) and validation group (n = 565) in a 3:2 ratio. In the investigation group, significant independent prognostic factors for predicting 1-year survival were identified. A scoring system for predicting 1-year mortality was developed which was validated in the validation group. RESULTS: Multivariate analysis revealed that the following seven variables were significant independent factors for 1-year survival: age ≧78, preoperative comorbidity, total gastrectomy, postoperative complication (Clavien-Dindo classification CD â‰§ 3a), stage III and IV, and R2 resection. While developing a 1-year mortality score (OMS), an age ≧78 was scored 2, preoperative comorbidity, total gastrectomy, and postoperative complication (CD â‰§ 3a) were scored 1, and stage III, IV, and R2-resection were scored 2, 3, and 3, respectively. OMS 3 had a sensitivity of 91% and a specificity of 66% for predicting death within 1 year. In the validation group, OMS 5 had a sensitivity of 55% and a specificity of 93% for predicting death within 1 year. CONCLUSIONS: OMS may provide important information and help surgeons select the timing of ACP in patients with GC.

Genome sequence of Vibrio sp. strain 10N, an ulvan-degrading bacterium isolated from coastal seawater collected at Ise Bay, Japan.

Genome sequence of an ulvan-degrading bacterium, Vibrio sp. strain 10N, is presented. The genome is 5,358,550 bp with a G + C content of 46.5%. A total of 4,712 coding sequences, including two novel ulvan lyase genes encoding a BNR4 and a glycoside hydrolase (GH88) motif, are known to be involved in the degradation of green algae.

Clinical features and risk factors for appendiceal diverticulitis: a comparative study with acute appendicitis.

PURPOSE: Despite their similar clinical characteristics, appendiceal diverticulitis (AD) and acute appendicitis (AA) are pathologically distinct. This study compared the clinical features of AD and AA and identified relevant risk factors. METHODS: Patients who underwent appendectomy with a preoperative diagnosis of either AD or AA were categorized based on histopathological findings. The two groups were compared in terms of various clinical factors. RESULTS: Among the 854 patients included in the study, a histopathological evaluation revealed 49 and 805 cases of AD and AA, respectively. A univariate analysis demonstrated that AD was more prevalent than AA among older, taller, and heavier males. A multivariate analysis revealed that male sex, a white blood cell (WBC) count < 13.5 × 103/µL, an eosinophil count ≥ 0.4%, and a mean corpuscular volume (MCV) ≥ 91.6 fL were significant factors differentiating AD from AA. In addition, pathological AD emerged as an independent risk factor for abscess and/or perforation. CONCLUSIONS: AD was associated with an older age, robust physique, and significant risk of abscess and/or perforation despite a low WBC count. In addition to imaging modalities, the preoperative factors of male sex, a WBC count < 13.5 × 103/µL, an eosinophil count ≥ 0.4%, and a MCV ≥ 91.6 fL may be useful for distinguishing AD from AA.

Significance of Preoperative Pulmonary Function on Short- and Long-Term Outcomes Following Gastrectomy for Gastric Cancer.

BACKGROUND: Preoperative pulmonary function assessment is useful for selecting surgical candidates and operative methods and assessing the risk of postoperative pulmonary complications. However, few studies have investigated the relationship between preoperative pulmonary function and short- and long-term outcomes in patients who underwent gastrectomy for gastric cancer. METHODS: Of the 1040 patients with gastric cancer (stages I-III) who had undergone R0 gastrectomy between 2009 and 2020, 750 who underwent preoperative spirometry were included. Restrictive ventilatory impairment was defined as a vital capacity of the predicted value (%VC) < 80%, while obstructive ventilatory impairment was defined as forced expiratory volume in one second (FEV1%) < 70%. Postoperative complications were assessed using the Clavien-Dindo (CD) classification. The relationship between clinical factors, including %VC, FEV1%, severe postoperative complications (CD ≥ 3b), overall survival (OS), and relapse-free survival, were assessed. RESULTS: The mean age of the 750 patients was 68 ± 10.5 years. Severe postoperative complications were observed in 25 (3.3%) patients and were significantly associated with FEV1% < 70% in the univariate analysis. The 5-year OS was 72.5%. Multivariate analysis showed that the cancer stage, age > 75 years, preoperative comorbidities, %VC < 80%, total gastrectomy, severe postoperative complications, and postoperative adjuvant chemotherapy were the significant independent factors affecting OS. Pneumonia was significantly associated with %VC < 80%. CONCLUSIONS: FEV1% < 70%was associated with the development of severe postoperative complications, while %VC < 80% was associated with poor OS independent of the cancer stage because of death from pneumonia. Spirometry helps surgeons and patients discuss the risks and benefits of surgery.

Long-term survivor who underwent surgical resections of repeated peritoneal oligometastases from colon cancer : a rare case report.

A 74-year-old woman underwent right hemicolectomy and partial ileal resection for ascending colon cancer with synchronous peritoneal metastasis. Histopathological examination showed moderately differentiated adenocarcinoma with mucinous component, pT4b N3 M1, and Stage IV. Postoperative chemotherapy comprising 36 courses of mFOLFOX6 with bevacizumab was administered. Twenty-two months after the surgery, computed tomography (CT) revealed a 20 mm nodular lesion adjacent to the gastric wall, and laparoscopic resection of the nodule was performed. Thirty-nine months after the second surgery, CT showed a 24 mm nodular lesion involving the liver parenchyma, and partial hepatectomy involving the nodule was performed. Histopathological examination of the nodules resected by the second and third surgeries showed the same features as the primary ascending colon cancer. The nodules were diagnosed as metachronous peritoneal metastases. The patient followed up without chemotherapy after the second and third surgery, showed no recurrence for 26 months after the third surgery. Fortunately, more than 7 years have passed since the primary tumor resection. Hence, surgical resection for synchronous and repeated metachronous peritoneal oligometastases from colon cancer can offer long-term survival. J. Med. Invest. 69 : 302-307, August, 2022.

Diagnosis and clinical implication of collision gastric adenocarcinomas: a case report.

BACKGROUND: Collision tumors are a subtype of simultaneous tumors wherein two unrelated tumors collide or infiltrate each other. Collision gastric adenocarcinomas (CGA) are rare and difficult to diagnose, and their clinical implications remain unclear. Herein, we aimed to reveal diagnostic methods for CGA and provide insight into its implications. CASE PRESENTATION: Among 1041 cases of gastric cancers (GCs) resected between 2008 and 2018, we included cases of confirmed CGA. Patients' backgrounds, preoperative endoscopy findings, macroscopic imaging findings, and histopathology findings [including immunostaining for CK 7, MUC2, and mismatch repair (MMR) proteins] were investigated. The incidence of CGA was 0.5%: 5 of 81 cases having simultaneous multiple GCs. Tumors were mainly in the distal stomach. The CGA in two cases was between early cancers, in two cases was between early and advanced cancers, and in one case was between advanced cancers. There were three cases of collision between differentiated and undifferentiated types and two cases between differentiated types. Immunostaining with CK7 and MUC2 was useful for diagnosing collision tumor when the histology was similar to each other. Among ten GCs comprising CGA, nine tumors (90%) exhibited deficient MMR proteins, suggesting high microsatellite instability (MSI). CONCLUSIONS: CGA is rare and usually found in the distal stomach. Close observation of shape, optimal dissection, and detailed pathological examination, including immunostaining, facilitated diagnosis. CGAs may have high MSI potential.

Non-tumor forming and diffusely spreading invasive pancreatic cancer.

A 78-year-old man presented to our hospital with loss of appetite and epigastric discomfort. Computed tomography (CT) revealed dilation of the main pancreatic duct and three cystic lesions in the pancreatic neck, body, and tail. Endoscopic ultrasonography showed a mural nodule > 5 mm enhanced with Sonazoid in a cyst. Therefore, the patient was diagnosed with intra-ductal papillary mucinous neoplasm (IPMN) and underwent distal pancreatectomy. Macroscopic examination of the cut surface of the resected specimen showed no solid tumors in the pancreatic parenchyma. The histopathological diagnosis of the cysts was IPMN with low-grade dysplasia. Ten months after surgery, the serum carbohydrate antigen 19-9 level was elevated, and CT showed multiple peritoneal and pulmonary nodules, suggesting peritoneal dissemination and lung metastases. Since recurrence of pancreatic cancer was suspected, repeat histopathological examination of the resected specimen was performed, revealing small clusters of atypical epithelial cells diffusely spreading in the pancreatic tissue. The diagnosis was changed to invasive ductal carcinoma (pT2N1bM0, stage IIB). Invasive pancreatic cancer that does not form a solid mass, and shows diffuse spreading with small clusters is extremely rare. Imaging diagnosis and histopathological examination should be carefully performed in such cases.

Isolation, Diversity and Characterization of Ulvan-Degrading Bacteria Isolated from Marine Environments.

In this study, we aimed to isolate bacteria capable of degrading the polysaccharide ulvan from the green algae Ulva sp. (Chlorophyta, Ulvales, Ulvaceae) in marine environments. We isolated 13 ulvan-degrading bacteria and observed high diversity at the genus level. Further, the genera Paraglaciecola, Vibrio, Echinicola, and Algibacter, which can degrade ulvan, were successfully isolated for the first time from marine environments. Among the 13 isolates, only one isolate (Echinicola sp.) showed the ability not only to produce externally expressed ulvan lyase, but also to be periplasmic or on the cell surface. From the results of the full-genome analysis, lyase was presumed to be a member of the PL25 (BNR4) family of ulvan lyases, and the bacterium also contained the sequence for glycoside hydrolase (GH43, GH78 and GH88), which is characteristic of other ulvan-degrading bacteria. Notably, this bacterium has a unique ulvan lyase gene not previously reported.

Production of 4-Deoxy-L-erythro-5-Hexoseulose Uronic Acid Using Two Free and Immobilized Alginate Lyases from Falsirhodobacter sp. Alg1.

Falsirhodobacter sp. alg1 expresses two alginate lyases, AlyFRA and AlyFRB, to produce the linear monosaccharide 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH) from alginate, metabolizing it to pyruvate. In this study, we prepared recombinant AlyFRA and AlyFRB and their immobilized enzymes and investigated DEH production. Purified AlyFRA and AlyFRB reacted with sodium alginate and yielded approximately 96.8% DEH. Immobilized AlyFRA and AlyFRB were prepared using each crude enzyme solution and κ-carrageenan, and immobilized enzyme reuse in batch reactions and DEH yield were examined. Thus, DEH was produced in a relatively high yield of 79.6%, even after the immobilized enzyme was reused seven times. This method can produce DEH efficiently and at a low cost and can be used to mass produce the next generation of biofuels using brown algae.

Portal vein leiomyosarcoma invading the pancreatic head.

We encountered a rare case of a pancreatic head tumor protruding into the portal vein, later diagnosed histopathologically as primary leiomyosarcoma of the portal vein. A 59-year-old woman visited our hospital because of an elevated amylase level during a medical checkup. Computed tomography showed a moderately contrasted, well-defined mass of 35-mm diameter in the pancreatic head with protrusion into the portal vein. Endoscopic ultrasonography revealed a well-defined and hypoechoic mass. Fluorodeoxyglucose-positron emission tomography showed a high accumulation of fluorodeoxyglucose in the pancreas head. We performed a subtotal stomach-preserving pancreaticoduodenectomy with portal vein resection. Gross findings of the fixed specimen showed a white solid, multinodular mass in the pancreatic parenchyma with protrusion into the portal vein. Histopathological examination showed proliferation of spindle-shaped eosinophilic cells with intricate bundle-like growth, indicating leiomyosarcoma. Examining the tumor location and invasion suggested portal vein as the origin. Although portal vein primary leiomyosarcoma is rare, leiomyosarcoma should be considered as a differential diagnosis in pancreatic head tumors with protrusion into the portal vein. Precise macroscopic and histopathological examinations can help determine the definitive diagnosis and origin of leiomyosarcoma.

SMARCA4-deficient rectal carcinoma with a sarcomatoid component: a case report.

A new classification of SMARCA4-deficient tumors was proposed recently for thoracic malignancies, and the tumors have some histopathological characteristics similar to those of carcinosarcoma. We encountered a case of SMARCA4-deficient rectal carcinoma with a sarcomatoid component. A 46-year-old man presented to our hospital with a prolapsing anal mass. Colonoscopy revealed an irregular, nodular, and elevated lesion in the rectum, and the biopsy revealed a moderately differentiated adenocarcinoma. Abdominoperineal resection of the rectum was performed. A macroscopic image of the resected specimen showed a complex tumor 3.5 cm × 3 cm in size with a papillary protrusion and an irregular ulcerative lesion. Histopathological examination revealed that the tumor was composed of moderately/poorly differentiated adenocarcinoma and atypical spindle cells. The adenocarcinoma component was positive for epithelial markers (AE1/AE3 and carcinoembryonic antigen) and showed deletion of SMARCA2 and SMARCA4, while the spindle cells expressed mesenchymal markers (α-smooth muscle actin and vimentin). The pathological diagnosis was poorly differentiated adenocarcinoma with a sarcomatoid component, pT3N2bM0, stage IIIc. Although our case had histological characteristics of carcinosarcoma, immunostaining revealed a deficiency of SMARCA4. This case presented a SMARCA4-deficient colorectal carcinoma with a sarcomatoid component, which was histopathologically similar to carcinosarcoma.

Superficial spreading type of early gastric cancer with diagnostic difficulty and positive surgical margin: a case report.

An 83-year-old man visited our hospital because of difficulty swallowing. Gastroscopy revealed multiple ulcers and a reddish depression in the lesser curvature of the middle stomach. The initial biopsy showed regenerative atypia, so a gastroscopy was repeated every 3 months thereafter because of suspected malignancy. A biopsy performed 12 months after the initial gastroscopy revealed a well-differentiated adenocarcinoma. After determination of the planned oral resection line by two negative biopsies, laparoscopic distal gastrectomy was performed. The resected specimen showed a 0 - IIa + IIc lesion composed of well-to-moderately differentiated tubular adenocarcinoma, including hand-shaking-type gastric cancer. The oral resection margin was positive due to widespread mucosal extension; therefore, an additional total gastrectomy was needed. Cases of well-differentiated adenocarcinoma and its superficial extension may be difficult to diagnose via endoscopy and biopsy.

Appendix-preserving elective herniorrhaphy for de Garengeot hernia: two case reports.

BACKGROUND: Emergency appendectomy is often performed for de Garengeot hernia. However, in some cases, there may be a chance to perform an appendix-preserving elective surgery. CASE DESCRIPTION: A 76-year-old woman presented to our hospital with complaints of a right inguinal swelling, which we diagnosed as a de Garengeot hernia using computed tomography (CT). B-mode ultrasonography (US) of the mass showed an appendix 4-6 mm in diameter with a clear wall structure; color Doppler US showed pulsatile blood flow signal in the appendiceal wall. Twenty-eight days later, herniorrhaphy with transabdominal preperitoneal repair (TAPP) was performed without appendectomy. Another 70-year-old woman presented to our hospital with complaints of a painful bulge in the right inguinal region. The diagnosis of de Garengeot hernia was made using CT. B-mode US showed an appendix 5 mm in diameter with a clear wall structure. Color Doppler US showed a pulsatile blood signal in the appendiceal wall. Seven days later, herniorrhaphy with TAPP was performed without appendectomy. CONCLUSION: De Garengeot hernia is often associated with appendicitis; however, an appendix-preserving elective herniorrhaphy can be performed if US and intraoperative findings do not suggest appendicitis or circulatory compromise in the appendix.

Strangulating bowel obstruction due to a small intestinal knot in a case of parastomal hernia.

An intestinal knot is a rare cause of intestinal obstruction. We report a rare case of strangulating bowel obstruction due to a small intestinal knot. A 69-year-old man who had an end colostomy was admitted with severe abdominal pain and vomiting. Contrast enhancement computed tomography showed dilated intestinal loops with decreased contrast enhancement in the parastomal hernia sac. Emergent laparotomy revealed a dilated and congested intestinal loop strangulated by a small intestinal knot. The knot was carefully untied, and the color of the intestinal loop improved subsequently. Intestinal resection was not performed. Immediate diagnosis and prompt surgical treatment are crucial for strangulating small bowel obstruction due to an intestinal knot. A high degree of clinical suspicion of an intestinal knot is needed in patients with a large extra-abdominal cavity.

Optimal cutoff value of preoperative CEA and CA19-9 for prognostic significance in patients with stage II/III colon cancer.

PURPOSE: This unicentric, retrospective cohort study aimed to identify the optimal cutoff values of preoperative serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) for the prognosis in patients with stage II/III colon cancer. METHODS: After excluding 43 patients with CA19-9 levels < 0.2 U/mL, 588 were included. Receiver operating characteristic curves were constructed to determine the optimal cutoff values of CEA and CA 19-9 for disease relapse. RESULTS: The median CEA and CA19-9 values were 3.6 (interquartile range: 2.1-7.2 ng/mL) and 14.3 (interquartile range: 8.1-30.0) U/mL, respectively. The optimal cutoff values of CEA and CA19-9 were 5.4 ng/mL and 22.4 U/mL, respectively. A multivariate analysis of relapse-free survival (RFS) showed that cancer stage, CEA, and CA19-9 were significant independent factors. The RFS of patients with stages II and III colon cancer was significantly stratified by CEA (< 5.4/ ≥ 5.4 ng/mL) and CA19-9 (< 22.4/ ≥ 22.4 U/mL). Prognostication based on the reference values (< 5.0 ng/mL for CEA and < 37.0 U/mL for CA19-9) was less significant than that based on the optimal cutoff values. Both elevated CEA and CA19-9 had no value dependency on RFS: RFS curves were similar between extremely elevated CEA (≥ 54.0 ng/ml) and intermediate CEA (5.4-54.0 ng/ml) and between extremely elevated CA19-9 (≥ 224.0 U/ml) and intermediate CA19-9 (22.4-224.0 U/ml). CONCLUSION: The optimal cutoff values of preoperative CEA and CA19-9 for RFS were 5.4 ng/ml and 22.4 U/mL, respectively, in patients with stages II and III colon cancer. Further relapse risk stratification is possible using these values.

Superficial spreading type of early gastric cancer coexisting with multiple hyperplastic polyps.

We encountered a rare case that involved the superficial spreading type of early gastric cancer coexisting with multiple hyperplastic polyps. An 81-year-old Japanese woman with a history of Helicobacter pylori infection was diagnosed with gastric cancer (cT1bN0M0), which presented as a wide, nodular, aggregated protrusion that was associated with multiple pedunculated and sessile polyps. Distal gastrectomy was performed, and the resected specimen involved an 8 cm × 4 cm nodular aggregated protruding lesion and 15 polyps that were 2-20 mm in size. Histopathological examination revealed that the nodular aggregated protruding lesion was a mucosal adenocarcinoma and that the multiple polyps were hyperplastic. The coexistence of multiple hyperplastic polyps and mucosal adenocarcinoma with nodular aggregated protrusions suggested that the mucosal adenocarcinoma had developed from a fusion of multifocal hyperplastic lesions. This may have occurred via a hyperplasia-carcinoma sequence related to the Helicobacter pylori infection. The superficial spreading type of early gastric cancer has a potential developed from a fusion of multifocal hyperplastic polyps.

Clinicopathological characteristics of De Garengeot hernia: six case reports and literature review.

BACKGROUND: De Garengeot hernia, wherein the appendix is present within a femoral hernia, is a rare disease; therefore, the clinicopathological features remain to be clarified. This study aimed to reveal the clinicopathological characteristics of De Garengeot hernia. CASE PRESENTATION: Six patients who underwent appendectomy and herniorrhaphy between 1999 and 2018 were included. The incidence of De Garengeot hernia was 3.2% among the 182 femoral hernias that required surgery during the study period. The median age of the patients was 78 years, and five patients were women. The median body mass index was 20.1. Patients frequently had fever or elevated CRP level. Preoperative diagnoses based on computed tomography were femoral (n = 3), inguinal (n = 2), and De Garengeot (n = 1) hernias. Emergency and elective surgeries were performed in four and two patients, respectively. Histopathological examination of the resected appendix showed gangrenous appendicitis (n = 3), perforated appendicitis (n = 2), and appendiceal ischemia (n = 1) in the patients. Postoperatively, one patient developed sepsis. CONCLUSIONS: Preoperative diagnosis of De Garengeot hernia is often difficult, and patients frequently have severe appendicitis. Precise diagnosis is required, and emergency surgery should be considered depending on the severity of appendicitis.

Mucosal prolapse syndrome-like inflammatory polyp protruding from the appendiceal orifice masquerading as an appendiceal neoplasm: A rare case report.

We describe a case of a mucosal prolapse syndrome (MPS)-like inflammatory polyp protruding from the appendiceal orifice, mimicking an appendiceal neoplasm. A 48-year-old man presented with lower abdominal pain and elevated white blood cell count and C-reactive protein level. Computed tomography showed a swollen appendix with multiple small saccular lesions and periappendiceal fat stranding and small saccular lesions in the ascending colon and cecum. Ultrasonography showed a swollen appendix 25 mm in diameter with multiple saccular structures and a periappendiceal high-echoic area, suggesting appendiceal diverticulitis. Colonoscopy revealed an erythematous lesion protruding from the appendiceal orifice. An ileocecal resection was performed based on a preoperative diagnosis of appendiceal diverticulitis and tumor. Histopathological examination of the appendix showed multiple mucosal herniations with infiltration of inflammatory cells, indicating appendiceal diverticulitis. The tumor was characterized by glandular duct hyperplasia and stromal expansion with smooth muscle hyperplasia and was diagnosed as an inflammatory polyp resembling an MPS lesion. Although several studies have shown the macroscopic and endoscopic appearance of MPS-like inflammatory lesions associated with colonic diverticular disease, this case was the first to present an inflammatory polyp associated with appendiceal diverticulitis in which the lesion protruding from the appendiceal orifice was masquerading as an appendiceal neoplasm.

CA19-9 is a significant prognostic marker of patients with stage III gastric cancer.

BACKGROUND: Due to prognostic heterogeneity within a stage of gastric cancer (GC), identification of patients with a high risk for recurrence after resection is important. We aimed to identify the prognostic significance of preoperative serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels in patients with Stage I, II, and III GC who underwent R0 gastrectomy. METHODS: A total of 794 patients were included in this study after excluding 72 patients with CA19-9 <1.0 U/mL. Receiver operating characteristic curves were drawn to assess the optimal cut-off values of CEA and CA19-9 for disease recurrence. RESULTS: The optimal cut-off values of CEA and CA19-9 levels were 2.9 ng/mL and 46.3 U/mL, respectively. Multivariate analysis for relapse-free survival (RFS) showed that stage of GC, CA19-9 levels, postoperative adjuvant chemotherapy, and venous invasion were significant independent factors. The RFS and overall survival (OS) of patients with CA19-9 ≥ 46.3 U/mL were significantly lower than those with CA19-9 < 46.3 U/mL in Stage III GC. However, the RFS of GC patients with CA19-9 ≥ 463 U/mL tended to be better than those with CA19-9 levels between 46.3 and 463 U/mL. CONCLUSIONS: The RFS and OS of patients with CA19-9 ≥ 46.3 U/mL were significantly lower than those with CA19-9 < 46.3 U/mL in Stage III GC. However, there was no value dependency of extremely elevated CA19-9 on RFS. Further risk stratification can be obtained by measuring preoperative serum CA19-9 in stage III GC.

Chronological Changes in Appendiceal Pathology Among Patients Who Underwent Appendectomy for Suspected Acute Appendicitis.

BACKGROUND: Given recent advances in imaging and the development of diagnostic parameters, the rate of unnecessary appendectomy (i.e., negative appendectomy) has been decreasing. However, the incidence of acute appendicitis (AA) in elderly patients is rising due to the aging of society. We aimed to identify chronological changes in demographics and appendiceal pathology among patients who underwent appendectomy for suspected AA. METHODS: Data from 881 patients who underwent appendectomy for suspected AA between January 2006 and December 2017 were analyzed. The final diagnosis was based on intraoperative findings, pathological reports, and clinical course. Negative appendectomy was defined as the absence of appendiceal diseases including inflammation, fibrosis, and neoplasm. We compared demographics and appendiceal pathology between early (2006-2011) and late study phases (2012-2017). RESULTS: The mean age of patients with pathologically proven AA (n = 761) was significantly greater in the late phase than in the early phase (38.6 ± 19.8 years vs. 44.0 ± 20.3 years, p = 0.0002), and the ratio of patients with AA aged ≧ 75 years was also increased (from 5.6 to 8.6%, p = 0.1120). The incidences of complicated appendicitis (defined as perforated or gangrenous appendicitis) and appendiceal diverticulitis (AD) were increased in the late phase compared to those in the early phase (61.3% vs. 77.2% and 3.7% vs. 6.6%, respectively). The negative appendectomy rate was significantly reduced in the late phase compared to that in the early phase (10.0% vs. 2.5%, p < 0.0001). CONCLUSIONS: During a 12-year period, the mean age of patients with AA and the incidences of complicated appendicitis and AD increased, whereas the negative appendectomy rate decreased.