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Introduction: Two-stage hepatectomy (TSH) enables patients to undergo surgery for colorectal liver metastasis (CRLM), which one-stage hepatectomy cannot remove. Although the outcome of TSH has been reported, there is no original report from Japan. The aim of this retrospective study was to evaluate the outcome of TSH in Japanese patients with CRLM., Methods: The authors conducted a retrospective cohort study using the nationwide database that included clinical information of 12 519 patients treated with CRLM between 2005 and 2017 in Japan. The primary outcome measure was overall survival. The second outcome measure was progression-free survival. Fisher's exact test, χ 2 test and Mann-Whitney U test were conducted to examine an intergroup difference. Univariate and multivariate analyses were performed using Cox regression model. Survival analysis was performed by Kaplan-Meier method and log-rank test., Results: Of the database, 53 patients undergoing TSH using portal vein embolization (PVE) were identified and analyzed. Their morbidity and in-hospital mortality rates at the second hepatectomy were 26.4% and 0.0%. The mean observation period was 21.8 months. The estimated 1-, 3- and 5-year overall survival rate were 92.5%, 70.8% and 34.7%. Multivariate analyses showed that more than 10 liver nodules significantly increased the mortality risk by 4.2-fold (95% CI 1.224-14.99, P = 0.023). Survival analysis revealed that repeat hepatectomy for disease progression after TSH was superior to chemotherapy in overall survival (mean: 49.6 vs. 18.7, months, P = 0.004)., Conclusion: In the Japanese cohort, TSH was confirmed to be a safety procedure with an acceptable survival outcome. More than 10 liver nodules may be a predictor for unfavorable outcomes of patients with CRLM undergoing TSH. Furthermore, repeat hepatectomy can be a salvage treatment for resectable intrahepatic recurrence after TSH., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

To improve treatment outcomes in patients with colorectal liver metastasis (CRLM), the Joint Committee for Nationwide Survey on CRLM was established by the Japanese Society for Cancer of the Colon and Rectum and the Japanese Society of Hepato-Biliary-Pancreatic Surgery. The aim of the study was to evaluate transition in the characteristics and treatment strategy in CRLM patients and analyze prognostic factors using large-scale data. The present study summarizes the data of patients newly diagnosed between 2015 and 2017 and presents prognostic data of patients newly diagnosed in 2013 and 2014. Survival curves were generated by the Kaplan-Meier method and compared by log-rank test. Multivariate analyses were carried out using Cox proportional hazard modeling. The data of 4502 patients newly diagnosed with CRLM between 2015 and 2017 and the prognostic data of 2427 patients diagnosed in 2013 and 2014 are included. Regarding the 2013 and 2014 prognostic data, the 5-year overall survival (OS) rates of patients who underwent hepatectomy alone was 59.8%. Multivariate analyses identified age at diagnosis of CRLM ≥70 years, concomitant extrahepatic metastasis at diagnosis of CRLM, tumor depth of primary lesion ≥subserosa/pericolic or perirectal tissue, mutant KRAS status, number of CRLM ≥5, maximum diameter of CRLM >5 cm, and surgical curability R1/R2 as independent predictors of OS. Analysis of the latest nationwide database of patients diagnosed with CRLM revealed changes in patients and oncological characteristics, a transition in treatment strategy, and different independent prognosticators to those reported previously., (© 2022 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: The Japanese Society of Hepato-Biliary-Pancreatic Surgery (JSHBPS) nomogram was developed to predict disease-free survival in patients with colorectal liver metastases (CRLM) undergoing upfront hepatectomy. However, the utility of the nomogram in patients with resected CRLM remains unknown in the current situation in which treatment strategies are changing with advances in drugs., Methods: Patients in the initial nomogram cohort (n = 727) and validation cohort (n = 2225) were divided into the upfront hepatectomy and preoperative chemotherapy groups. The nomogram was validated by measuring calibration and discrimination in the two cohorts. Calibration curves were plotted, and survival probabilities were compared. Finally, to quantify the discrimination power, we estimated the concordance index (C-index)., Results: In the upfront hepatectomy group, the C-index was 0.63, the suitable cutoff value of the Beppu score was 7, and adjuvant chemotherapy was significantly effective limited to high-risk patients (Beppu score ≥7). The C-index was 0.56 in the preoperative chemotherapy group., Conclusions: The JSHBPS nomogram remains beneficial for patients undergoing upfront hepatectomy in the recent era but is less effective for patients undergoing hepatectomy after chemotherapy. Patients with a Beppu score ≥7 showed high-risk recurrence, and adjuvant chemotherapy should be recommended for these patients., (© 2022 The Authors. Journal of Hepato-Biliary-Pancreatic Sciences published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: The conventional H category-based classification for colorectal liver metastases (CRLM) was created by equal weighting of tumor number and tumor size; however, our previous nomogram to predict postoperative disease-free survival demonstrated that CRLM ≥5 as a parameter provided 4.5 times greater impact compared with a largest CRLM size >5 cm., Methods: A total of 3815 patients newly diagnosed with CRLM between 2005 and 2007, including 2220 resectable cases, were investigated. Six groups were created based on largest lesion size (≤ 5 vs >5 cm) and lesion number (1, 2-4, and ≥5)., Results: The novel (n) H1, nH2, and nH3 categories were defined as solitary lesions with a size ≤5 cm; lesions other than nH1 or nH3; and ≥5 lesions with any lesion size, respectively. In the resectable cohort, the 5-year cumulative overall survival rates were 64.0%, 53.5%, and 42.6% in the nH1, nH2, and nH3 groups, respectively (P < .001), and no significant differences were observed between the conventional H2 and H3 categories. In the overall cohort, the discrimination ability of the two classifications were comparable., Conclusion: The novel H category-based classification might be beneficial in predicting overall survival in patients with CRLM independent of their resectability., (© 2021 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background/purpose: The purpose of the present study was to assess long-term outcomes following liver resection for colorectal liver metastases (CRLM) with concurrent extrahepatic disease and to identify the preoperative prognostic factors for selection of operative candidates., Methods: In this retrospective, multi-institutional study, 3820 patients diagnosed with CRLM during 2005-2007 were identified using nationwide survey data. Data of identified patients with concurrent extrahepatic lesions were analyzed to estimate the impact of liver resection on overall survival (OS) and to identify preoperative, prognostic indicators., Results: Three- and 5-year OS rates after liver resection in 251 CRLM patients with extrahepatic disease (lung, n = 116; lymph node, n = 51; peritoneal, n = 37; multiple sites, n = 23) were 50.2% and 32.0%, respectively. Multivariate analysis revealed that a primary tumor in the right colon, lymph node metastasis from the primary tumor, serum carbohydrate antigen (CA) 19-9 level >37 UI/mL, the site of extrahepatic disease, and residual liver tumor after hepatectomy were associated with higher mortality. We proposed a preoperative risk scoring system based on these factors that adequately discriminated 5-year OS after liver resection in training and validation datasets., Conclusions: Performing R0 liver resection for colorectal liver metastases with treatable extrahepatic disease may prolong survival. Our proposed scoring system may help select appropriate candidates for liver resection., (© 2020 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: To collect large-scale data for further research to improve treatment outcomes in patients with colorectal liver metastasis (CRLM), the Joint Committee for Nationwide Survey on CRLM was established by the Japanese Society for Cancer of the Colon and Rectum and the Japanese society of Hepato-Biliary-Pancreatic Surgery. The joint committee was initiated to collect data since 2014 and has already reported data including the prognostic data of 3820 patients newly diagnosed with CRLM between 2005 and 2007., Methods: The data of patients newly diagnosed with CRLM after 2013 are continuously being registered prospectively, and herein, we report the data of the patients newly diagnosed with CRLM in 2013 and 2014., Results: The data of 3839 patients newly diagnosed with CRLM in 2013 and 2014 were registered from 156 departments (75%) of 152 institutions among 209 departments (from 201 institutions) that agreed to participate in this database system at its initiation. Finally, 3525 patients were enrolled in this study after a quality management process conducted by the joint committee. We report the comprehensive data obtained from 3525 patients, including clinicopathological findings, treatment strategies, and implementation status of chemotherapy., Conclusion: The joint committee will provide these raw data while updating prognostic data to researchers who will conduct meaningful studies that meet the aim of the joint committee., (© 2020 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: The survival benefit of and indications for adjuvant chemotherapy (AC) for colorectal liver metastases (CRLM) remain unclear., Methods: Patients who were diagnosed with liver-limited CRLM between 2005 and 2007 and subsequently underwent R0 resection without preoperative chemotherapy were identified in a Japanese nationwide survey. This overall cohort was divided into synchronous and metachronous CRLM cohorts. In each of the three cohorts, the patients that were given AC were matched with those treated with surgery alone via 1:1 propensity score (PS) matching. Recurrence-free survival (RFS) and overall survival (OS) after the initial hepatectomy were compared., Results: The median follow-up period was 79.4 months and the overall, synchronous, and metachronous cohorts included 1145, 498, and 647 patients, respectively. After the PS matching, the patients' demographics were well balanced. AC was effective in terms of both RFS and OS in the overall cohort (RFS hazard ratio [HR] 0.784, p = 0.045; OS HR 0.716, p = 0.028) and synchronous cohort (RFS HR 0.677, p = 0.027; OS HR 0.642, p = 0.036), whereas AC was not effective in the metachronous cohort (RFS HR 0.875, p = 0.378; OS HR 0.881, p = 0.496). However, in the metachronous cohort, AC was effective in terms of OS in the subgroup that exhibited disease-free intervals of ≤ 1 year after primary tumor resection (RFS HR 0.667, p = 0.068; OS HR 0.572, p = 0.042)., Conclusion: Adjuvant chemotherapy has a survival benefit for patients with resected CRLM. Synchronous CRLM is a favorable indication for AC, whereas in metachronous CRLM, the use of AC should be individualized according to each patient's risk factors.

To collect big data for further research to improve treatment outcomes in patients with colorectal liver metastasis (CRLM), the Joint Committee for Nationwide Survey on CRLM was established by the Japanese Society for Cancer of the Colon and Rectum and the Japanese Society of Hepato-Biliary-Pancreatic Surgery. The joint committee initiated data collection since 2014. The data of 4,237 patients newly diagnosed with CRLM between 2005 and 2007 were registered from 134 departments of 127 institutions (64%) among 209 departments (from 201 institutions) that agreed to participate in this study. Finally, 3,820 patients were enrolled in this report after a quality management process by the joint committee. We report the comprehensive data obtained from 3,820 patients, clinicopathological findings, treatment strategies, prognoses, and implementation status of chemotherapy. The joint committee is prospectively collecting data of patients newly diagnosed with CRLM after 2013 and will provide these raw data, including data of patients diagnosed between 2005 and 2007, to researchers who will conduct meaningful studies that meet the aim of the joint committee., (© 2017 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: A Japanese multicenter study disclosed four prognostic indicators of colorectal cancer liver metastases: ≥5 hepatic tumors (HT), HT size > 5 cm, nodal status (N2) of primary cancer, and the presence of extrahepatic metastases (EM). The Japanese classification was then defined as Stage A, HT1 (≤4 lesions and ≤5 cm) and N0/1; Stage B, HT2 (≥5 lesions or >5 cm) and N0/1, or HT1 and N2; and Stage C, HT2 and N2, HT3 (≥5 lesions and >5 cm) with any N, or EM1 (presence of EM) with any HT/N. This study aimed to validate the prognostic reliability in a recent population and to develop a modified staging system that divided Stage C patients., Methods: A total of 1185 patients diagnosed with liver metastases between 2007 and 2008 were enrolled in the study. According to the classification, 358, 257, and 570 patients were categorized as Stages A, B, and C, respectively. Stage C was further divided into two groups: Stage C-I, HT3 and N0/1, HT2 and N2, or HT1 and EM1; and Stage C-II, HT3 and N2, or HT2/3 and EM1., Results: Cumulative overall survival curves for Stages A, B, and C were significantly different between each two stages (p < 0.0001, p < 0.0001). The modified system discriminated patients with a relatively better outcome (Stage C-I) from desperate patients (Stage C-II) (p < 0.0001)., Conclusions: The Japanese classification system was adequately validated in a recent population, and the modified system is useful in risk stratification of Stage C cases.

Colorectal cancer is a major cause of death in Japan, where it accounts for the largest number of deaths from malignant neoplasms among women and the third largest number among men. Many new methods of treatment have been developed during recent decades. The Japanese Society for Cancer of the Colon and Rectum Guidelines 2014 for treatment of colorectal cancer (JSCCR Guidelines 2014) have been prepared as standard treatment strategies for colorectal cancer, to eliminate treatment disparities among institutions, to eliminate unnecessary treatment and insufficient treatment, and to deepen mutual understanding among health-care professionals and patients by making these guidelines available to the general public. These guidelines have been prepared as a result of consensuses reached by the JSCCR Guideline Committee on the basis of careful review of evidence retrieved by literature searches and taking into consideration the medical health insurance system and actual clinical practice in Japan. They can, therefore, be used as a guide for treating colorectal cancer in clinical practice. More specifically, they can be used as a guide to obtaining informed consent from patients and choosing the method of treatment for each patient. As a result of the discussions of the Guideline Committee, controversial issues were selected as clinical questions, and recommendations were made. Each recommendation is accompanied by a classification of the evidence and a classification of recommendation categories, on the basis of consensus reached by Guideline Committee members. Here we present the English version of the JSCCR Guidelines 2014.

Background/aims: To validate the conventional Japanese grading of liver metastasis for no residual tumor resection in Stage IV colorectal cancer (CRC) with liver metastasis and to identify risk factors for postoperative recurrence., Methodology: The subjects of this study were 1792 Stage IV CRC patients with liver metastasis., Results: In 1792 cases, including unresectable cases, there was a significantly different prognosis by grade (P < 0.0001). In 421 R0 cases, there was no significant difference between Grade A and Grade B (P = 0.8527). In 381 cases without extra-hepatic metastasis, the prognosis was not significantly different among three grades. On multivariate analysis, carcinoembryonic antigen within 3 months from R0 operation (3M-CEA) was an independent risk factor regardless of extrahepatic metastasis. There was a significantly different prognosis (P < 0.0001) among Grade A', defined as a normal 3M-CEA level, Grade B', defined as Grade A or B and an abnormal 3M-CEA level, and Grade C', defined as Grade C and an abnormal 3M-CEA level., Conclusions: The postoperative CEA level is an important risk factor during follow-up after curative resection in patients with liver metastatic colorectal carcinoma. The combination of the 3M-CEA level and conventional grading of liver metastasis is useful for follow-up of R0 resection cases.

Objective: To evaluate the feasibility of oral fluoropyrimidines after resection and microwave coagulation(MCT), or radiofrequency ablation(RFA)of liver metastases from colorectal cancer., Patients and Methods: Background factors, fluoropyrimidine administration(S-1 or UFT/LV), and adverse events were analyzed in 20 patients(17 males, 3 females; an average of 62. 4 years)with colorectal liver metastases after resection and RFA or MCT., Results: The synchronous: metachronous metastases ratio was 13:7. Fifteen patients received the recommended dose and 5 received a reduced dose. S-1 was administered for 4 weeks followed by a 2-week rest for 7 patients, and for 2 weeks followed by a 1-week rest for 9 patients. UFT/LV was administered for 4 weeks followed by a 1-week rest for 4 patients. Fourteen patients(70%)had adverse events. One patient showed grade 3 leukocyte toxicity while other patients showed grade 1 or 2. Two patients discontinued chemotherapy because of grade 2 delirium and grade 2 CPK elevation; another 2 discontinued voluntarily. Eight patients with recurrence changed the rugs, while 8 of 12(67%)continued for 1 year. Median disease-free and med ian overall survival lengths were 16. 1 and 4 7. 6 months, respectively., Conclusion: S-1 and UFT /LV were used safely as adjuvant chemotherapies after the resection and local coagulation therapy of liver metastases.

A 74-year-old female patient underwent a simultaneous colectomy and hepatectomy for sigmoid colon cancer and its hepatic metastases. Six months later she underwent a hepatectomy for recurrent hepatic metastases; then 10 months later, a pulmonary resection for pulmonary metastasis; and 24 months later, a partial gastrectomy for gastric metastasis. As of December 2005, at 7 years 6 months after the first surgery and at 4 years after the last surgery, the patient is still alive with a good quality of life and no sign of recurrence.

As the hepatic metastasis from breast cancer has a tendency to have an extrahepatic lesion, systemic therapy therefore becomes acclimatization. However, local therapy is regarded as one of the choices if there is no extrahepatic lesion. We present three cases of liver metastasis from the breast treated by radiofrequency ablation (RFA). Case 1: A 65-year-old woman was treated by left mastectomy in 1997. Radiation exposure was performed for lung metastasis, and a weekly paclitaxel therapy was administered in 2001. We performed RFA percutaneously for liver metastasis of 2.8 cm in 2002. The aggravation spread to the lung lesion and she died after RFA within one year. The liver metastasis finally enlarged to 4 cm in size. Case 2: A 36-year-old woman was treated by left mastectomy (Stage IIIa), and was followed by chemotherapy in 2000. We performed RFA for metastasis of 2 cm of liver (S7) percutaneously in 2001, and didn't recognize a recurrence to date for 3 years and 8 months. Case 3: A 43-year-old woman was treated by left mastectomy (Stage IIIa), and followed by chemotherapy in 2003. We performed RFA for a liver metastasis of 3.5 x 4 cm under laparotomy in 2004. She has been disease free for 15 months.

Extracranial multiple metastases from meningeal hemangiopericytoma have been reported only rarely. The authors describe the case of a 61-year-old woman, who was previously diagnosed as having primary meningeal hemangiopericytoma with its multiple metastases to the liver, lumbar spine, etc. and who suffered from a sudden attack of hypoglycemia. Considering the history of her present illness, this hypoglycemic shock was most likely brought on by the remarkable metastatic tumors to the liver. Recent literature pertinent to hypoglycemia suggests that insulin-like growth factor-II (IGF-II) produced by tumor is strongly suspected to be involved in the development of hypoglycemia.

Purpose: Although hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the human liver, the molecular changes and mechanisms that regulate its development and progression remain unclear. In the present study, we investigated the correlation between beta-catenin expression and clinical outcome in 51 patients with relatively small (maximal diameter < 30 mm), solitary HCCs., Experimental Design: The tumors were classified according to histological tumor differentiation (grade I, 11 tumors; grade II, 28 tumors; grade III, 12 tumors). Using immunohistochemical methods to detect nuclear accumulation of beta-catenin, we investigated the correlation between beta-catenin expression and clinical outcome and compared the correlation with cyclin D1, Ki-67, and E-cadherin., Results: Focal or generalized nuclear beta-catenin expression was observed in 36.4% (4 of 11) of the grade I tumors, 39.3% (11 of 28) of the grade II tumors, and 25% (3 of 12) of the grade III tumors. Nuclear beta-catenin-positive grade III tumors were associated with significantly poorer survival (P = 0.004), whereas none of the patients with nuclear beta-catenin-negative grade I tumors died. With regard to proliferative activity, positive nuclear beta-catenin staining correlated significantly with an increased Ki-67 labeling index in grade I (P < 0.0001) and grade III (P = 0.0045) tumors and with reduced epithelial cadherin expression in the cell membrane (P < 0.001). In contrast, no association with the expression of cyclin D1, one of the target factors of beta-catenin, was detected., Conclusions: Our present data suggest that beta-catenin plays important roles in promoting tumor progression by stimulating tumor cell proliferation and reducing the activity of cell adhesion systems and is associated with a poor prognosis, especially in patients with poorly differentiated HCCs.

Fibrolamellar hepatocellular carcinoma (FHCC), a rare variant of hepatocellular carcinoma, is becoming more prevalent; however, up until 1999, only 18 cases had been reported in Japan. We recently diagnosed a case of FHCC in a 46-year-old Japanese man who had visited four hospitals before being finally admitted to our department. On admission, he was diagnosed as having multiple liver tumors, with lymph node metastasis and peritoneal dissemination. Both hepatitis B antigen and hepatitis C antibody were negative, and the levels of serum alpha-fetoprotein and PIVKA-II were within normal limits. Under a provisional diagnosis of atypical hepatocellular carcinoma (HCC), a right hepatic lobectomy with resection of the metastatic lymph nodes and peritoneal dissemination was performed. The histopathological diagnosis made by our pathologist was atypical HCC. He underwent another operation for a recurrence in the left external iliac lymph node. It has been 29 months since his first surgery in this hospital and he is progressing well, which led us to establish the diagnosis of FHCC. Moreover, his serum carbohydrate antigen 125 levels have been well correlated with this condition.

Hepatitis C virus (HCV) infection is associated with a wide spectrum of liver diseases including cirrhosis and hepatocellular carcinoma (HCC). Although the biological relation between the virus and cirrhosis or HCC is unclear, such variable pathogenicity may be related to the genetic heterogeneity of HCV. Genetic variability of HCV was assessed by determining the nucleotide sequence corresponding to the hypervariable regions (HVR1 and HVR2) of the putative envelope protein (E2/NS1) in positive- and negative-stranded HCV RNA from the cancerous and surrounding non-cancerous liver tissue, peripheral blood mononuclear cells and serum of a patient with HCC. Nineteen distinct HVR1 amino acid sequences (deduced from the nucleotide sequences) were obtained from the patient and could be classified into 5 groups on the basis of the site and time of detection. Some viral isolates with the same HVR1 sequence were shown to replicate in both cancerous and non-cancerous liver tissue, whereas others replicated in HCC tissue only.

A 57-year-old man with high alpha-fetoprotein (AFP) and suspected submucosal tumour of the stomach was referred for investigation. A 6 cm hypervascular tumour with tumour vessels in the left diaphragm was diagnosed by a combination of angiography and computed tomography. At laparotomy, the tumour was confirmed to be located just beneath the left diaphragm and to be isolated from the liver parenchyma. The resected specimen was histopathologically hepatocellular carcinoma. The level of AFP returned to normal, and the patient is free of recurrence 8 years after operation.

Regulation of the formation of microbodies in Morris hepatoma 9618A was studied by examination of the response of the organelles to clofibrate. The fine structures of microbodies in the hepatoma cells closely resembled those in hepatocytes of normal adult rats. In clofibrate-treated rats, the tumor cells showed a slight increase in the size of microbodies and in catalase activity; however, the tumor microbodies did not increase in number. In contrast, in adult clofibrate-treated rats and rats on the day of birth whose mothers received clofibrate during the gestation period, the hepatocytes showed microbodies that were greater in both number and size, and the catalase activity in the liver was definitely elevated.

Histochemical investigations used the 3,3'-diaminobenzidine reaction to demonstrate the catalase activity and thus variations in numbers of peroxisomes, and electron microscopic examinations were made of hyperplastic liver lesions in rats fed 0.06%3'-methyl-4-dimethylaminoazobenzene. At the 10th week of carcinogen feeding, hyperplastic lesions (hyperplastic foci, areas, and nodules) appeared and advanced to further stages. Most of the foci and some of the areas and nodules showed very low catalase activity and, correspondingly, a small number of peroxisomes. When rats were administered ethyl-alpha-p-chlorophenoxyisobutyrate, most of the foci, areas, and nodules showed a moderate increase in catalase activity and in peroxisome number. Hyperplastic foci seemed to grow larger with time to form hyperplastic areas and/or nodules, mostly accompanying maturation as well as proliferation of the hepatocytes involved. Maturation is well characterized by an increase in the endogenous level of catalase and in the number of peroxisomes, as well as by an enhancement of the responsiveness to ethyl-alpha-p-chlorophenoxyisobutyrate. However, there was a small proportion of lesions in which all cells or some cells did not mature and thus were considered persistently altered. It is suggested that these altered cells serve mainly as intimate precursors of hepatomas.

Five patients with hepatocellular carcinoma in the caudate lobe were evaluated. Computed tomography (CT) scan and/or angiography clearly demonstrated multiple intrahepatic metastases in four (80%), and tumor thrombi in the portal vein in two (40%), and in the inferior vena cava in one. Even though there was no recognizable lung metastasis, metastases were found in the orbita in one patient, and in the ribs and thoracic vertebrae in two patients. Four patients died after a mean period of 5.5 months from the initial diagnosis. The mechanism for early invasion into the vessels and multiple intrahepatic metastases of hepatocellular carcinoma arising from the caudate lobe is discussed.

Peroxisomes were present in trabecular carcinoma and adenocarcinoma induced by 3-methyl-4-(dimethylamino)azobenzene in the liver of rats. Peroxisomes in well-differentiated trabecular carcinoma (type I) resembled more or less those in hepatocytes in their electron microscopic features, but were considerably small in number. Poorly differentiated trabecular carcinoma (type II) and adenocarcinoma contained peroxisomes in far smaller number than in the well-differentiated trabecular carcinoma, or frequently showed no peroxisomes. Peroxisomes in poorly differentiated trabecular carcinoma and adenocarcinoma were small in size, contained scanty matrix in general, and almost lacked crystalloid nucleoids; however, they were easily identified by electron microscopic cytochemistry of catalase. Catalase activity of these tumors was significantly lower than in the liver tissues. These tumors did not respond to ethyl chlorophenxyisobutyrate either by proliferation of peroxisomes or by elevation of catalase activity. It is thus suggested that the cellular mechanisms for regulating the formation of peroxisomes and synthesis of the enzyme involved are impaired in the tumor cells.