Weekday Surgery Associated With Short-Term Outcomes in Patients With Colorectal Cancers.

INTRODUCTION: The "weekday effect" on elective surgery remains controversial. We aimed to examine the association between the day of surgery and short-term outcomes after elective surgery for stage I-III colorectal cancer (CRC). METHODS: We performed a multicenter retrospective analysis of 2574 patients who underwent primary colorectal resection for CRC between January 2017 and December 2019 at 15 institutions belonging to the Hiroshima Surgical Study Group of Clinical Oncology. Patients were divided into two groups according to the day of surgery: Friday and non-Friday (Monday to Thursday). After propensity score matching (PSM), we compared 30-day mortality and postoperative outcomes. RESULTS: Out of the total, 368 patients underwent surgery on Fridays, and the remaining 2206 underwent surgery on non-Fridays. The overall mortality rate was 0.04% (n = 1). In 1685 patients with colon cancer, the proportion of American Society of Anesthesiologists scores was significantly lower in the Friday group than in the non-Friday group before PSM. After PSM of patient, tumor, and operative characteristics, operative time was slightly more prolonged and blood loss was slightly greater in the Friday group; however, these differences were not clinically meaningful. In the 889 patients with rectal cancer, the proportion of patients with abnormal respiratory patterns was significantly lower in the Friday group than in the non-Friday group before PSM. After PSM, the Friday group had a higher incidence of morbidity (≥ Clavien-Dindo 3a), higher incidence of digestive complications, and prolonged postoperative hospital stay. CONCLUSIONS: The results may be useful in determining the day of the week for CRC surgery, which requires more advanced techniques and higher skills.

Survival outcomes of patients with stage III colorectal cancer aged ≥ 80 years who underwent curative resection: the HiSCO-04 prospective cohort study.

BACKGROUND: The efficacy of adjuvant chemotherapy in elderly patients aged ≥ 80 years with stage III colorectal cancer remains unclear. In parallel with a multicenter prospective phase II trial evaluating the efficacy of uracil-tegafur and leucovorin as adjuvant chemotherapy (HiSCO-03), we conducted a prospective observational study of these patients to assess survival outcomes, including those ineligible for chemotherapy. METHODS: This multi-institutional prospective cohort study included 17 institutions in Hiroshima, Japan. Patients aged ≥ 80 years with stage III colorectal cancer who underwent curative resection were enrolled. The primary endpoint was 3-year disease-free survival, and the secondary endpoints were 3-year overall and relapse-free survival. Propensity score matching was used to assess the effects of adjuvant chemotherapy on survival outcomes. RESULTS: A total of 214 patients were analyzed between 2013 and 2018, including 99 males and 115 females with a median age of 84 years (range 80-101 years). Recurrence occurred in 58 patients and secondary cancers were observed in 17. The 3-year disease-free, overall, and relapse-free survival rates were 63.3%, 76.9%, and 62.9%, respectively. Adjuvant chemotherapy was administered to 65 patients with a completion rate of 52%. In a study of 80 patients that adjusted for background factors using propensity score matching, patients who completed the planned treatment showed improved disease-free survival (3-year disease-free survival: completed, 80.0%; not received, 65.5%; and discontinued, 56.3%; p = 0.029). CONCLUSIONS: Completion of adjuvant chemotherapy may improve the prognosis of patients with colorectal cancer aged ≥ 80 years, although the number of patients who would benefit from it is limited.

Association between social background and implementation of postoperative adjuvant chemotherapy for older patients undergoing curative resection of colorectal cancers, sub-analysis of the HiSCO-04 study.

PURPOSE: Adjuvant chemotherapy is recommended following colorectal cancer resection based on risk of recurrence. In older patients, treatment decisions should consider recurrence rates and tolerability, as well as functional prognosis, residual disease, and social factors. This study aims to investigate factors, including social background, influencing implementation of postoperative adjuvant chemotherapy in older patients undergoing curative resection for colorectal cancer. METHODS: This multi-institutional prospective cohort study included 15 institutions belonging to the Hiroshima Surgical study group for Clinical Oncology. We analyzed 159 older patients aged ≥ 80 years, who underwent curative resection for stage III colorectal cancer between December 2013 and June 2018, as sub-analysis of the HiSCO-04 study. RESULTS: In total, 62 (39.0%) patients underwent postoperative adjuvant chemotherapy. Four factors were significantly associated with its implementation: performance status < 2, Charlson Comorbidity Index < 2, prognostic nutritional index ≥ 40, and presence of a spouse or siblings as lifestyle supporters. No significant difference was found in the backgrounds between complete and incomplete postoperative adjuvant chemotherapy patients. CONCLUSION: Performance status, Charlson Comorbidity Index, nutritional status, and presence of a spouse or siblings as lifestyle supporters are possible factors influencing the implementation of postoperative adjuvant chemotherapy in older patients. To select appropriate treatment options, including postoperative adjuvant chemotherapy, it is essential to consider physical condition and comorbidities of older patients, thoroughly explain the situation to their families, and establish a support system to enhance understanding of the available treatment options.

Predictive factors associated with anastomotic leakage after resection of rectal cancer: a multicenter study with the Hiroshima Surgical study group of Clinical Oncology.

PURPOSE: Several factors have been reported as risk factors for anastomotic leakage after resection of rectal cancer. This study aimed to evaluate the risk factors for anastomotic leakage, including nutritional and immunological indices, following rectal cancer resection. METHODS: This study used a multicenter database of 803 patients from the Hiroshima Surgical study group of Clinical Oncology who underwent rectal resection with stapled anastomosis for rectal cancer between October 2016 and April 2020. RESULTS: In total, 64 patients (8.0%) developed postoperative anastomotic leakage. Five factors were significantly associated with the development of anastomotic leakage after rectal cancer resection with stapled anastomosis: male sex, diabetes mellitus, C-reactive protein/albumin ratio ≥ 0.07, prognostic nutritional index < 40, and low anastomosis under peritoneal reflection. The incidence of anastomotic leakage was correlated with the number of risk factors. The novel predictive formula based on odds ratios in the multivariate analysis was useful for identifying patients at high risk for anastomotic leakage. Diverting ileostomy reduced the ratio of anastomotic leakage ≥ grade III after rectal cancer resection. CONCLUSIONS: Male sex, diabetes mellitus, C-reactive protein/albumin ratio ≥ 0.07, prognostic nutritional index < 40, and low anastomosis under peritoneal reflection are possible risk factors for developing anastomotic leakage after rectal cancer resection with the stapled anastomosis. Patients at high risk of anastomotic leakage should be assessed for the potential benefits of diverting stoma.

Prognostic value of preoperative carcinoembryonic antigen and D-dimer concentrations in patients undergoing curative resection for colorectal cancer.

PURPOSE: Carcinoembryonic antigen (CEA) has limited value as a standalone predictor of the survival in patients with colorectal cancer (CRC). D-dimer (DD) is a predictor of the survival in patients with metastatic CRC. We aimed to predict the prognosis in patients undergoing curative resection for the treatment of CRC by integrating the evaluation of preoperative CEA and DD concentrations with the pathological classification for stage grouping (pStage). METHODS: The study enrolled 304 patients between 2007 and 2012. The Combination of DD and CEA Score (CDCS) awarded 1 point each for a CEA concentration of > 5.0 ng/ml and DD concentration of > 1.0 µg/ml. Patients were classified according to the total points: CDCS 2, increased DD and CEA concentrations; CDCS 1, increased concentration of either DD or CEA; CDCS 0, normal concentrations. RESULTS: The overall survival (OS) and relapse-free survival (RFS) were significantly lower in patients with CDCS 2 than in those with CDCS 1 or 0. The pStage and CDCS were not independent prognostic predictors of the OS but were predictors of the RFS. The C-index value of the combination of the pStage and CDCS was better than that of either alone for the OS and RFS. CONCLUSION: The combination of the pStage and CDCS accurately predicts relapse in patients with CRC.

[A Case of Gastric Cancer with Continued Progression-Free Survival Even after Total Gastrectomy and Nivolumab Therapy].

This is a first report of gastrectomy after nivolumab immunotherapy. We describe a case in an elderly woman with gastric cancer diagnosed with cT4bN3M1(LYM), cStage ⅣB disease. Although she was administered 2 courses of SOX chemotherapy as the primary treatment, she could not continue the treatment to due to bone marrowsuppression. The second-line treatment was weekly PTX therapy, but she experienced Grade 3 neutropenia and thrombocytopenia in the first course and could not continue treatment. Nivolumab as the next treatment was effective but was discontinued for suspected druginduced pneumonia. During that time, tumor hemorrhage occurred and we performed total gastrectomy. Postoperatively, nivolumab chemotherapy was resumed. There were no adverse events and the patient has had a continued partial response for 30 courses. Gastrectomy was necessary in this case, allowing observation of the pathological findings of this highly effective case.

[A Case of Duodenal Invasive Advanced Gastric Cancer in Which the Primary Tumor Achieved pCR, but Viable Cancer Cells Remained in Lymph Node No.13 after Neoadjuvant Chemotherapy].

A woman approximately 70-years-old with duodenal invasive advanced gastric cancer was referred to our hospital. Meta- stasis to lymph node(LN)No.13 was suspected based on FDG/PET-CT. For better curability, we selected neoadjuvant chemotherapy( NAC)with S-1 plus oxaliplatin(SOX therapy). After 3 courses of SOX, distal gastrectomy with D2(+No.13) lymphadenectomy was performed. Upon pathological evaluation, no viable cancer cells were found in the primary tumor, but viable cancer cells were identified in LN No.6 and 13. LN No.13 was defined as M1 according to the current Japanese classification of gastric carcinoma. On the other hand, the 2014 Japanese gastric cancer treatment guidelines(ver. 4)mentioned that D2(+No.13)lymphadenectomy may be an option in potentially curative gastrectomy for tumors invading the duodenum. This case suggests that No.13 lymphadenectomy is necessary as a curative operation for duodenal invasive advanced gastric cancer, even if the primary tumor has achieved pCR after NAC.

[Clinical Outcome of Hepatectomy of Liver Metastasis of Duodenal Ampullary Cancer].

We evaluated the clinical outcome and assessed the indication of hepatectomy for liver metastasis of duodenal ampullary cancer. We analyzed 42 cases of duodenal ampullary cancer and 4 patients who underwent hepatectomy for liver metastasis. Eleven(50%)of 22 cases with recurrence of duodenal ampullary cancer had liver metastasis. Four cases were solitary and 7 cases were multiple. Four patients underwent hepatectomy didn't had other organ metastasis. Three of 4 cases with solitary liver metastases and one of 7 cases with multiple metastasis underwent hepatectomy. One of 3 cases of solitary liver metastasis died of lung and bone metastases without liver recurrence 2 years and 8 months after hepatectomy. Other 2 cases are long surviving without recurrence 8 years and 8 months and 4 years and 9 months after hepatectomy respectively. One case of multiple liver metastases died of early liver recurrence 10 months after hepatectomy. The indication of hepatectomy for liver metastasis was restrictive. However the prognosis of patients with solitary liver metastasis was relatively favorable. Therefore hepatectomy could be indicated for solitary liver metastasis of duodenal ampullary cancer.

[A Case of Anaplastic Carcinoma Spindle Cell Type of the Pancreas].

Anaplastic carcinoma spindle cell type is an extremely rare disease and its prognosis is very poor. We herein report a case of anaplastic carcinoma spindle cell type of the pancreas. A 50-year-old man complaining of epigastralgia was found to have a pancreatic body-tail tumor by abdominal US and CT studies. Abdominal CT showed an irregular poorly-enhanced 33mm tumor containing a cystic component. ERCP revealed the main pancreatic duct was cut off at the tumor. Cytology of the pancreatic fluids did not indicate malignancy. A pancreatic tumor with a cystic component similar to pancreatic neoplasms containing cystic degeneration or a mass-forming pancreatitis concomitant with pancreatic pseudocyst was suspected. Therefore, we performed distal pancreatectomy. Histological findings showed the center of the tumor was severely necrotized and oval or spindle dysplastic cells proliferated around the peripheral area. According to the immunohistological staining pattern, the patient was diagnosed as having anaplastic carcinoma spindle cell type. He was administered oral S-1 for 6 months and is now recurrence-free, surviving for 15 months after pancreatectomy. Reports of long-term survival cases that also demonstrated R0 resection should be indicated in the treatment of anaplastic carcinoma spindle cell type despite the poor prognosis.

[A Case of Mixed Hepatocellular and Primary Hepatic Neuroendocrine Carcinomas with Remnant Liver Recurrence and Rapid Exacerbation].

The patient was a 77-year-old man with a 4.0 cm hepatictumor in hepaticsegment 4. Plain computed tomography(CT) showed the tumor with low density. On dynamicexamination, the tumor showed heterogeneous enhancement during the arterial phase. Magneticresonanc e imaging showed the tumor as a low intensity area in the hepatobiliary phase in hepatic segments 4, 6, and 8. A month later, CT showed an enlarged tumor in segment 4 measuring 7.0 cm. We diagnosed the tumor as primary liver cancer and suspected it to be hepatocellular carcinoma(HCC)preoperatively. We performed extended medial segmentectomy and partial hepatectomy of segment 6. The histopathological diagnosis was mixed HCC and primary hepatic neuroendocrine carcinoma(PHNEC). Three months after hepatectomy, the patient died of multiple intrahepatic recurrences. In most of the reported cases of mixed HCC and PHNEC, only the PHNEC component has been detected in the biopsy of the metastatic lesions. This fact might suggest that PHNEC has a higher proliferative activity and malignant potential than HCC. Standard treatment for mixed HCC and PHNEC is unclear; therefore, development of multidisciplinary treatment strategies combining surgical treatment and systemic chemotherapy is required.

[Assessment of Endoscopic Resection and Partial Duodenectomy for Duodenal Mucosal Tumor].

INTRODUCTION: The risk of perforation following endoscopic resection is high. We analyzed the outcome of partial duodenectomy and discussed the therapeutic strategy for duodenal mucosal tumor(DMT). PATIENTS AND METHODS: We analyzed 19 cases who have undergone endoscopic resection, and 11 cases who have undergone partial duodenectomy for DMT in our institute since 2007. We divided them into the first period(ESD actively indicated)and late period(ESD carefully indicated according to the alteration of indication of ESD for DMT in 2013)groups. RESULTS: In the first period, all 17 cases initially underwent endoscopic resection and 4 cases were complicated by perforation. On the other hand, in the late period, 6 of 12 cases initially underwent endoscopic resection and 1 case was complicated by perforation. Emergent partial duodenectomy was performed with additional resection in the perforation cases. There were no complications associated with surgery, and all 29 cases achieved curative resection, based on the histology results. CONCLUSION: We can safely indicate endoscopic resection for DMT with surgical back-up and cooperation with the endoscopic internal department.

[A Long-Surviving Case of Unresectable Gall Bladder Carcinoma Treated with Gemcitabine-Based Chemotherapy].

We report a 5-year surviving patient with unresectable gall bladder carcinoma treated with gemcitabine(GEM)-based chemotherapy. A 64-year-old man was diagnosed with unresectable gall bladder carcinoma with peritoneal dissemination based on laparotomy findings. Two months later, he started to receive GEM chemotherapy. Twelve months after surgery, the patient chose to suspend GEM treatment. One year and 10 months later, multiple lung metastases appeared and GEM was restarted in combination with UFT. Although the primary lesion and lung metastases gradually progressed, the patient maintained a good quality of life. After 3 years and 2 months, chemotherapy was changed to GEM plus S-1 because of progressive disease. Five years and 2 months after surgery, his condition was complicated by a secondary pneumothorax, and the patient received home oxygen therapy. Five years and 8 months after surgery he died of respiratory distress caused by the progression of lung metastases. Even in the case of unresectable advanced gall bladder carcinoma, effective chemotherapy could improve quality of life and prolong survival.

[Report of a Case of Long-Term Survival with Mulitidisciplinary Therapy for a Patient with Multiple Liver Metastases from Rectal Cancer].

Multidisciplinary therapy is necessary to prevent recurrence of advanced rectal cancer and advanced cancer with metastases. Here we report a case of long-term survival of a patient with advanced rectal cancer with multiple liver metastases. An 80's woman had previously undergone both Hartmann's operation and a partial hepatectomy for advanced rectal cancer with multiple liver metastases. A year after chemotherapy, a CT scan revealed multiple liver metastases. Thus, we performed partial liver resection. After another round of chemotherapy, a CT scan revealed lung metastases and local recurrence of the rectal cancer; therefore, we performed partial lung resection and a Miles operation. These procedures were conducted 4 years after her first operation. The following year, PET-CT revealed a mediastinum lymph node metastasis; consequently, we performed radiation therapy. New lung metastases and local recurrences of rectal cancer were identified after the radiation therapy; thus, we resumed the therapy, including a molecular targeting drug. Although the patient is in a tumor-bearing state, she is still alive 10 years after her first operation.

[Two Cases of Locally Recurrent Rectal Cancer after Intersphincteric Resection That Were Controlled with a Combination of Chemoradiotherapy and Abdominoperineal Resection].

We report 2 cases of locally recurrent rectal cancer after intersphincteric resection(ISR)that were controlled with a combination of chemoradiotherapy and abdominoperineal resection(APR). In Case 1, we performed preoperative chemoradiotherapy( TS-1 plus RT 45 Gy)and APR for the local recurrence of ISR. On pathology, viable neoplastic cells were noted. In Case 2, we performed preoperative chemotherapy(Bmab plus mFOLFOX6)and APR for the local recurrence of ISR. On pathology, no viable neoplastic cells were noted. However, a local recurrence developed again 3 months later. Therefore, we performed chemoradiotherapy(TS-1 plus RT 53 Gy). The 2 patients survived without recurrence until now. Their pathology tissues and clinical courses showed that control of local recurrence with only chemoradiotherapy or surgical resection was likely to be difficult. We might be able to improve the prognosis of patients with a combination of chemoradiotherapy and surgical resection.

Virtual reality training followed by box training improves the laparoscopic skills of novice surgeons.

BACKGROUND: The detailed influence of virtual reality training (VRT) and box training (BT) on laparoscopic performance is unknown; we aimed to determine the optimal order of imparting these training programs. MATERIAL AND METHODS: This randomized controlled trial involved two groups, each with 20 participants without prior laparoscopic surgical experience: A BT-VRT group (60 min BT followed by 60 min VRT) and a VRT-BT group (60 min VRT followed by 60 min BT). We objectively assessed the laparoscopic skills with a motion-analysis system (Hiroshima University Endoscopic Surgical Assessment Device: HUESAD), which reliably assesses surgical dexterity. Skill assessment was performed before and after the training session. RESULTS: No inter-group differences were identified in the study measures at the pre-training assessment. In both groups, the performance on all tasks was significantly better at the post-training assessment than at the pre-training assessment. However, the outcome of the tests using the HUESAD was significantly better in the VRT-BT group than in the BT-VRT group at the post-training assessment. CONCLUSIONS: VRT followed by BT effectively improves the dexterity of novice surgeons during initial laparoscopic (combination) training.

Percutaneous Trans-Esophageal Gastrostomy for Oral Intake in a Case of Anastomotic Obstruction following Total Gastrectomy.

Gastric cancer is one of the most common diseases globally. Total gastrectomy is often performed surgically. However, late-stage anastomotic passage obstruction after total gastrectomy is relatively rare. Here, we report a case involving a 73-year-old male patient who experienced repeated aspiration pneumonia due to anastomotic passage obstruction 22 years after a total gastrectomy for gastric cancer. He was eventually hospitalized in the Department of Gastroenterology at our hospital because of difficulty eating. Computed tomography revealed prominent dilation of the esophagus and the blind end of the elevated jejunum. Upper gastrointestinal endoscopy revealed a poorly extended site on the main side of the elevated jejunum; however, the passage through the scope was good. A percutaneous trans-esophageal gastrostomy was performed for oral intake. The patient experienced decreased nausea and vomiting. He gained weight, and his general condition improved. He did not feel inconvenienced by percutaneous trans-esophageal gastrostomy and had no desire for surgery. Follow-up observations are currently being conducted, with tubes exchanged every 6 months. There are no reports of percutaneous trans-esophageal gastrostomy for oral intake for anastomotic passage obstruction following total gastrectomy; therefore, we report this as a reference when similar cases are encountered.

A prospective feasibility study of uracil-tegafur and leucovorin as adjuvant chemotherapy for patients aged ≥ 80 years after curative resection of colorectal cancer, the HiSCO-03 study.

PURPOSE: There is no consensus on the safety and effectiveness of adjuvant chemotherapy for patients with stage III colorectal cancer (CRC) aged ≥ 80 years. We conducted a prospective multi-institutional phase II study of uracil-tegafur and leucovorin (UFT/LV) as adjuvant chemotherapy in this population. PATIENTS AND METHODS: Patients with stage III CRC aged ≥ 80 years who underwent curative resection were enrolled. Eligible patients received UFT/LV therapy (UFT, 300 mg/m2 per day as tegafur; LV, 75 mg/day on days 1-28, every 35 days for five courses). Primary endpoint was feasibility, and secondary endpoints were safety and relative dose intensity. RESULTS: Sixty-nine patients were enrolled between 2013 and 2021. Of the 69 patients, 65 were included in the analysis. There were 32 males and 33 females with a median age of 82 years (range 80-88 years). In the primary endpoint, administration completion rate was 67.3% (95% confidence interval 54.9-77.6%), and the lower limit of the 95% confidence interval was below the threshold of 60%. 21 patients discontinued treatment because of adverse events (AEs) and refused treatment. The median relative dose intensities were 84% (range 4-100%) for UFT, and 100% (range 4-100%) for LV. Incidence of grade three or higher AEs were neutropenia (1.5%), aspartate transaminase elevation (3%), alanine transaminase elevation (1.5%), oral mucositis (3%), anemia (1.5%), and diarrhea (4.6%). CONCLUSIONS: The indications for adjuvant UFT/LV therapy for elderly CRC aged ≥ 80 years were considered limited. It is necessary to clarify the background of patients in whom drug administration is discontinued and investigate their impact on long-term prognosis.

The importance of stressing the use of laparoscopic instruments in the initial training for laparoscopic surgery using box trainers: a randomized control study.

BACKGROUND: The goal of this study was to improve the efficiency of initial box training for laparoscopic surgery. MATERIALS AND METHODS: The study used the following task: suturing and knot tying task under a combination of four conditions. (1) The C (use of conventional instruments)-D (direct vision); (2) the C-V (indirect vision via a video monitor); (3) the L (use of laparoscopic instruments)-D; and (4) the L-V (the standard laparoscopic suturing and knot tying). The first study assessed 11 medical students undergoing L-V training. The time to complete each of the four assessment tasks was recorded pre- and post-training. The second study was a randomized, controlled trial involving 36 students grouped according to three types of training methods: the L-D, the C-V, and the L-V group. The improvement in the time to complete the L-V task was assessed and the Hiroshima University Endoscopic Surgical Assessment Device (HUESAD) was used for assessment as well. RESULTS: In the first study, a significant improvement in the performance time between pre- and post-training for the L-D task was found, but not for the C-V task. The second study found that the improvement rate of the L-D trained group was significantly greater than that of the C-V and L-V groups. The HUESAD assessment also showed the similar results. CONCLUSIONS: A training program stressing the use of laparoscopic instruments and compensating for the fulcrum effect is more effective for novices using box trainers in the initial laparoscopic surgery instruction than one emphasizing performing the tasks via a video monitor.

Approaching time is important for assessment of endoscopic surgical skills.

This study aimed to verify whether the approaching time (the time taken to reach the target point from another point, a short distance apart, during point-to-point movement in endoscopic surgery), assessed using the Hiroshima University Endoscopic Surgical Assessment Device (HUESAD), could distinguish the skill level of surgeons. Expert surgeons (who had performed more than 50 endoscopic surgeries) and novice surgeons (who had no experience in performing endoscopic surgery) were tested using the HUESAD. The approaching time, total time, and intermediate time (total time--approaching time) were measured and analyzed using the trajectory of the tip of the instrument. The approaching time and total time were significantly shorter in the expert group than in the novice group (p < 0.0001). The intermediate time did not significantly differ between the groups (p > 0.05). The approaching time, which is a component of the total time, is very mportant in the measurement of the total time to assess endoscopic surgical skills. Further, the approaching time was useful for skill assessment by the HUESAD for evaluating the skill of surgeons performing endoscopic surgery.

Alterations in portal vein blood pH, hepatic functions, and hepatic histology in a porcine carbon dioxide pneumoperitoneum model.

BACKGROUND: Intra-abdominal high pressure and acidosis by carbon dioxide (CO(2)) pneumoperitoneum is known to affect various organ functions. In this study, changes in liver functions and liver histology were investigated during CO(2) pneumoperitoneum in a large animal model. METHODS: Fourteen white pigs were anesthetized with intubation and controlled ventilation. The pigs in the pneumoperitoneum group (PG) were exposed to CO(2) pneumoperitoneum at an intra-abdominal pressure of 8 mmHg, and those in the open laparotomy group (OG) were subjected to laparotomy. Hemodynamics were measured and liver function tests were performed in the carotid artery and portal vein, and the liver tissue was histologically examined. RESULTS: The blood pressure, PO(2), PCO(2), and pH in the carotid artery did not significantly differ between the groups. In the PG, blood pressure, PO(2), and PCO(2) in the portal vein were elevated while the pH was low. There were no significant differences in the levels of aminotransferases and lactate between the groups. In the PG, the arterial ketone body ratio (AKBR) was low at 90 min and the ICG retention rate was high at 180 min; these values differed significantly compared to those at 0 min. Histological examination revealed liver congestion in the PG and no significant change in the OG. In the PG, the TUNEL assay revealed positive staining in the area with focal lytic changes. CONCLUSIONS: CO(2) pneumoperitoneum at an intra-abdominal pressure of 8 mmHg in a porcine model affected liver functions and caused histological changes in the liver. Although it is uncertain whether these alterations observed in the porcine liver occur in humans as well and whether the alterations are reversible after pneumoperitoneum, it may be necessary to pay attention to liver damage during laparoscopic surgery.