Conversion Surgery After Chemotherapy Plus Nivolumab as the First-Line Treatment for Unresectable Advanced or Recurrent Gastric Cancer and a Biomarker Study Using the Gustave Roussy Immune Score: A Multicenter Study.

BACKGROUND: There are few reports on conversion surgery (CS) after chemotherapy plus nivolumab as a first-line treatment in patients with unresectable advanced or recurrent gastric cancer (GC). This multicenter study was conducted to analyze real-world data on CS after chemotherapy plus nivolumab as a first-line treatment and to identify predictive biomarkers. METHODS: This multicenter study included 104 patients who received chemotherapy plus nivolumab as primary treatment for unresectable advanced recurrent GC from 12 institutes. We investigated and analyzed patient characteristics and blood test data in the presence or absence of CS, the relationship between the Gustave Roussy Immune Score (GRIm-s) and CS, and the characteristics of CS cases. RESULTS: CS was performed in 12 patients (11.5%). Eastern Cooperative Oncology Group Performance Status (ECOG-PS) was significantly better in patients who underwent CS (p < 0.0001). There were no CS cases with high-risk GRIm-s (0%), however there were 22 non-CS cases (23.9%). No high-risk GRIm-s cases were converted to CS. Minimally invasive surgery was performed in 50.0% of the cases, with R0 resection in all cases and only one case of urinary retention (Grade II) as a postoperative complication, indicating a good postoperative short-term outcome. There were two cases of postoperative recurrence (16.7%), both of which were grade 1b. CONCLUSIONS: The short-term postoperative results of CS after chemotherapy plus nivolumab as the first-line treatment for GC were acceptable in this study. There were no high-risk GRIm-s cases among those who underwent CS, suggesting that the GRIm-s may be a predictor of CS.

Impact of SARS-CoV-2 infection on short-term postoperative outcomes after gastroenterological cancer surgery using data from a nationwide database in Japan.

Background: Due to the coronavirus disease 2019 (COVID-19) pandemic, cancer screening, diagnosis, and treatment have changed. This study aimed to investigate the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection prior to gastroenterological cancer surgeries on postoperative complications using data from a nationwide database in Japan. Methods: Data on patients who underwent surgery for cancer including esophageal, gastric, colon, rectal, liver, and pancreatic cancer between July 1, 2019, and September 300, 2022, from real-world sources in Japan were analyzed. The association between preoperative SARS-CoV-2 infection and short-term postoperative outcomes was evaluated. A similar analysis stratified according to the interval from SARS-CoV-2 infection to surgery (<4 vs. >4 weeks) was conducted. Results: In total, 60 604 patients were analyzed, and 227 (0.4%) patients were diagnosed with SARS-CoV-2 infection preoperatively. The median interval from SARS-CoV-2 infection to surgery was 25 days. Patients diagnosed with SARS-CoV-2 infection preoperatively had a significantly higher incidence of pneumonia (odds ratio: 2.05; 95% confidence interval: 1.05-3.74; p = 0.036) than those not diagnosed with SARS-CoV-2 infection based on the exact logistic regression analysis adjusted for the characteristics of the patients. A similar finding was observed in patients who had SARS-CoV-2 infection <4 weeks before surgery. Conclusions: Patients with a history of SARS-CoV-2 infection had a significantly higher incidence of pneumonia. This finding can be particularly valuable for countries that have implemented strict regulations in response to the COVID-19 pandemic and have lower SARS-CoV-2 infection-related mortality rates.

Risk model for morbidity and mortality following liver surgery based on a national Japanese database.

Aim: We evaluated the morbidity and mortality associated with liver surgery in Japan and developed a risk model for liver resection using information from a national database. Methods: We retrospectively reviewed 73 861 Japanese patients who underwent hepatectomy between 2014 and 2019, using information from the National Clinical Database (NCD) registrations. The primary endpoints were 30 days and in-hospital mortality, and the secondary endpoints were postoperative complications. Logistic regression risk models for postoperative morbidity and mortality after hepatectomy were constructed based on preoperative clinical parameters and types of liver resection, and validated using a bootstrapping method. Results: The 30-day and in-hospital mortality rates were 0.9% and 1.7%, respectively. Trisectionectomy, hepatectomy for gallbladder cancer, hepatectomy for perihilar cholangiocarcinoma, and poor activities of daily living were statistically significant risk factors with high odds ratios for both postoperative morbidity and mortality. Internal validations indicated that the c-indices for 30-day and in-hospital mortality were 0.824 and 0.839, respectively. Conclusions: We developed a risk model for liver resection by using a national surgical database that can predict morbidity and mortality based on preoperative factors.

A case of resected anaplastic carcinoma of the pancreas producing granulocyte-colony stimulating factor with literature review.

BACKGROUND: Granulocyte colony-stimulating factor (G-CSF)-producing tumors have been reported in various organs, and the prognosis of patients with G-CSF-producing pancreatic cancers is particularly dismal. In this report, we present a case of G-CSF-producing anaplastic carcinoma of the pancreas (ACP), characterized by early postoperative recurrence and rapid, uncontrolled growth. CASE PRESENTATION: A 74-year-old man presented to our hospital with complaints of abdominal fullness and pain after eating. On admission, it was observed that the peripheral leukocyte counts and serum G-CSF levels were significantly elevated (23,770/µL and 251 pg/mL, respectively). Computed tomography of the abdomen revealed a pancreatic head tumor involving the superior mesenteric vein. Pathologically, ultrasound-guided fine-needle aspiration confirmed ACP. Subsequently, we performed a subtotal stomach-preserving pancreaticoduodenectomy with portal vein reconstruction and partial transverse colon resection. On postoperative day (POD) 7, the leukocyte count decreased from 21,180/µL to 8490/µL; moreover, computed tomography revealed liver metastasis. Therefore, mFOLFILINOX chemotherapy was initiated on POD 30. However, the tumor exhibited rapid progression, and the patient died on POD 45. CONCLUSIONS: G-CSF-producing ACP is rare, and the prognosis of patients is extremely poor. Basic research is required to develop effective drugs against G-CSF-producing tumors, and large-scale studies using national databases are needed to develop multidisciplinary treatment methods.

A Mature Tertiary Lymphoid Structure with a Ki-67-Positive Proliferating Germinal Center Is Associated with a Good Prognosis and High Intratumoral Immune Cell Infiltration in Advanced Colorectal Cancer.

Tertiary lymphoid structures (TLSs) are complex lymphocyte clusters that arise in non-lymphoid tissues due to inflammation or cancer. A mature TLS with proliferating germinal centers is associated with a favorable prognosis in various cancers. However, the effect of TLS maturity on advanced colorectal cancer (CRC) remains unexplored. We analyzed the significance of TLS maturity and tumor Ki-67 expression in surgically resected tumors from 78 patients with pathological T4 CRC. Mature TLS was defined as the organized infiltration of T and B cells with Ki-67-positive proliferating germinal centers. We analyzed the relationship between TLS maturity and intratumoral immune cell infiltration. Mature TLS with germinal center Ki-67 expression was associated with microsatellite instability and improved survival; however, high tumor Ki-67 expression was associated with poor survival in the same cohort. Multivariate analysis identified the absence of mature TLS as an independent predictor of poor post-recurrence overall survival. Intratumoral infiltration of T lymphocytes and macrophages was significantly elevated in tumors with mature TLS compared to those lacking it. High Ki-67 levels and absent mature TLS were identified as poor prognostic factors in advanced CRC. Mature TLS could serve as a promising marker for patients at high-risk of CRC.

Simple severity scale for perforated peptic ulcer with generalized peritonitis: A derivation and internal validation study.

BACKGROUND: Perforated peptic ulcer (PPU) causes peritonitis and requires surgery based on disease severity. This study aimed to develop and validate a severity scale for PPU with generalized peritonitis. MATERIALS AND METHODS: This retrospective cohort study used a nationwide multi-center surgical database (2013-2020). Patients aged >15 years who underwent surgery for PPU with generalized peritonitis were included and categorized into the derivation (2013-2018) and two validation (2019 and 2020) cohorts. Possible severity predictors were selected via a literature review, and Lasso models were developed to predict severe postoperative adverse events with 2000 bootstrapping. Final variables for the scoring system were determined based on inclusion frequency (≥90%) in the Lasso models. Discrimination and accuracy were evaluated using c-statistics and calibration plots. Cutoff values for minimal postoperative adverse events were examined using negative predictive values. RESULTS: Among 12,513 patients included (1,202 underwent laparoscopic surgery), 533 (5.9%), 138 (7.6%), and 117 (6.9%) in the derivation and two validation cohorts experienced postoperative adverse events. Age, dyspnea at rest, preoperative sepsis, III/IV/V of American Society of Anesthesiologists physical status, and albumin and creatinine were selected for the final model. A 0-11 scoring system was developed with c-statistics of 0.812-0.819. Cutoff value was determined as 5, which predicted <3% probability of postoperative adverse events regardless of type of surgery. CONCLUSIONS: A score of <5 predicts minimal risks for postoperative adverse events and therefore would be clinically useful to determine type of surgery. Further studies are needed to validate the score.

Intraoperative severe gastric venous congestion during total pancreatectomy with replaced common hepatic artery: a case report.

BACKGROUND: Gastric venous congestion (GVC) is one of the complications of total pancreatectomy (TP). Here, we report a case of intraoperative severe GVC during TP with a replaced common hepatic artery (RCHA). CASE PRESENTATION: A 65-year-old female patient was diagnosed with intraductal papillary mucinous carcinoma. Her CHA branched from the superior mesenteric artery as RCHA. She underwent subtotal stomach preserving TP. The tumor was resected with splenic artery (SpA) and total gastric vein transections. Severe GVC and bleeding from the stomach tube occurred intraoperatively. A strong pulsation was observed in the left gastric artery (LGA), and we suspected an increased blood flow from the celiac artery (CeA) to the LGA after SpA resection. Total gastrectomy (TG) was then performed to control the severe GVC-related bleeding. The patient was discharged without complications 19 days postoperatively. CONCLUSION: TP with RCHA may increase the risk of severe GVC due to increased blood flow from CeA to LGA.

Outcome research on esophagectomy analyzed using nationwide databases in Japan: evidences generated from real-world data.

Esophagectomy for esophageal cancer is a highly invasive gastrointestinal surgical procedure. The National Clinical Database (NCD) of Japan, initiated in 2011, has compiled real-world data on esophagectomy, one of nine major gastroenterological surgeries. This review examines outcomes after esophagectomy analyzed using the Japanese big databases. Certification systems by the Japanese Society of Gastroenterological Surgery (JSGS) and the Japan Esophageal Society (JES) have shown that institutional certification has a greater impact on short-term surgical outcomes than surgeon certification. Minimally invasive esophagectomy has emerged as a viable alternative to open esophagectomy, although careful patient selection is crucial, especially for elderly patients with advanced tumors. The NCD has significantly contributed to the assessment and enhancement of surgical quality and short-term outcomes, while studies based on Comprehensive Registry of Esophageal Cancer in Japan (CRECJ) have provided data on patient characteristics, treatments, and long-term outcomes. The JES has conducted various questionnaire-based retrospective clinical reviews in collaboration with authorized institutions certified by JES. The Diagnosis Procedure Combination (DPC) database provides administrative claims data including itemized prices for surgical, pharmaceutical, laboratory, and other inpatient services. Analyzing these nationwide databases can offer precise insights into surgical quality for esophageal cancer, potentially leading to improved treatment outcomes.

Successful radical surgery for lymph node metastasis in a patient with hepatocellular carcinoma following atezolizumab plus bevacizumab combination therapy: a case report and literature review.

A woman in her early 80 s was followed up in our hospital for chronic hepatitis C after viral eradication. We detected rapid-growing lymph node metastasis of hepatocellular carcinoma (HCC) after treatment with transcatheter arterial chemoembolization and/or radiofrequency ablation. We found that the metastasis was operable, but the size and location of the metastasis obliged the patient to receive pancreatoduodenectomy, which was too invasive. Then we initiated systemic chemotherapy to perform radical minimally invasive surgery. We treated the patient with 3 weekly cycles of atezolizumab 1200 mg plus bevacizumab 15 mg/kg. The patient tolerated the treatment well, and treatment-emergent adverse events included deterioration of hypertension and increased uric protein. After a total of 4 cycles of therapy, abdominal computed tomography findings showed that the metastasis evidently decreased, and a complete response was achieved based on the Revised Response Evaluation Criteria in Solid Tumors (RECIST) guidelines (version 1.1). Seventeen days later, the metastasis was dissected. Subsequently, we confirmed that there was no pathological metastatic lesion in the resected lymph node. Our case is the first report of successful application of the radical therapy to lymph node metastasis of HCC via combination therapy with atezolizumab/bevacizumab.

Risk Factors of Poor Outcomes After Colorectal Cancer Surgery for Patients With Severe Comorbidities.

BACKGROUND/AIM: An increasing number of patients with complicated systemic comorbidity can undergo colorectal cancer (CRC) surgery. Such patients have a high risk of developing poor postoperative outcomes. This study aimed to identify preoperative factors, including nutritional and sarcopenia statuses, leading to poor postoperative outcomes in patients with severe systemic comorbidities. PATIENTS AND METHODS: This study included 114 patients who underwent radical CRC resections and had American Society of Anesthesiologists Physical Statuses ≥3. We retrospectively analyzed the relationships between clinical factors, postoperative complications (within 28 days postoperatively and Clavien-Dindo classification grade ≥2), length of hospital stay, discharge destination, and overall survival (OS). RESULTS: The median patient age was 74.5 years (range=41.0-93.0 years). Thirty-six patients had postoperative complications (31.6%), and the risk factors in the multivariate analyses were rectal cancer and preoperative nutritional disorders with Prognostic Nutritional Index ≤40. In patients with nutritional disorders, the postoperative hospital stay was longer, and a higher (but not statistically significant) percentage were not discharged home. Moreover, the independent factors for OS identified in the multivariate analyses were body mass index (BMI) and hemodialysis. CONCLUSION: In patients with CRC and severe systemic comorbidities, those with Prognostic Nutritional Index ≤40 have a high risk of developing postoperative complications, leading to a prolonged postoperative hospital stay and possibly preventing discharge home. Additionally, among these patients, OS was poor in those with low BMI or preoperative hemodialysis.

Importance of duodenal stump reinforcement to prevent stump leakage after gastrectomy: a large-scale multicenter retrospective study (KSCC DELICATE study).

BACKGROUND: The significance of reinforcement of the duodenal stump with seromuscular sutures and the effectiveness of reinforced staplers in preventing duodenal stump leakage remain unclear. We aimed to explore the importance of duodenal stump reinforcement and determine the optimal reinforcement method for preventing duodenal stump leakage. METHODS: This retrospective cohort study was conducted between January 1, 2012 and December 31, 2021, with data analyzed between December 1, 2022 and September 30, 2023. This multicenter study across 57 institutes in Japan included 16,475 patients with gastric cancer who underwent radical gastrectomies. Elective open or minimally invasive (laparoscopic or robotic) gastrectomy was performed in patients with gastric cancer. RESULTS: Duodenal stump leakage occurred in 153 (0.93%) of 16,475 patients. The proportions of males, patients aged ≥ 75 years, and ≥ pN1 were higher in patients with duodenal stump leakage than in those without duodenal stump leakage. The incidence of duodenal stump leakage was significantly lower in the group treated with reinforcement by seromuscular sutures or using reinforced stapler than in the group without reinforcement (0.72% vs. 1.19%, p = 0.002). Duodenal stump leakage incidence was also significantly lower in high-volume institutions than in low-volume institutions (0.70% vs. 1.65%, p = 0.047). The rate of duodenal stump leakage-related mortality was 7.8% (12/153). In the multivariate analysis, preoperative asthma and duodenal invasion were identified as independent preoperative risk factors for duodenal stump leakage-related mortality. CONCLUSIONS: The duodenal stump should be reinforced to prevent duodenal stump leakage after radical gastrectomy in patients with gastric cancer.

Poorly cohesive gastric cancer with increased epithelial­mesenchymal transition is associated with a poor prognosis.

The present study examined the surgical outcome and prognosis of patients with poorly cohesive carcinoma (PCC), and characterized the molecular pathological factors, epithelial-mesenchymal transition (EMT) and interstitial signals of the disease. A total of 281 patients who underwent gastric cancer (GC) surgery between April 2015 and August 2020 were included. Furthermore, tissue samples from another 197 patients with GC who underwent surgery between 1999 and 2003 were assessed using a tissue microarray. Preoperatively treated cases and endoscopic submucosal dissection cases were excluded, and multiple blocks containing the invasion region were collected for tissue microarray. For tissue microarray analysis, the clinicopathological factors of protein wnt3a (wnt3a), leucine-rich repeat-containing G-protein coupled receptor 5, transforming growth factor-ß-induced, phosphorylated serine/threonine-protein kinase mTOR and E-cadherin expression were collected as EMT markers. The results of the surgical case evaluation and tissue microarray indicated that PCC was more common in younger patients and women, as the ratio of women to men was higher in the PCC group compared with that in the non-PCC group. However, none of the results revealed that the prognosis was worse in all patients with PCC compared with the non-PCC group. Furthermore, in the tissue microarray study, PCC samples exhibited significantly decreased expression of the cell adhesion molecule E-cadherin, suggesting enhanced EMT, which activates wnt3a signaling. PCC with increased EMT was significantly associated with a poor prognosis.

Advantages of laparoscopic segmentectomy of the liver using ICG fluorescent navigation by the negative staining method: A comparison with open procedure.

Aim: Laparoscopic segmentectomy (LS) using indocyanine green (ICG) fluorescence navigation with negative staining method has potential for performing accurate and safe anatomical excision. This study aimed to evaluate the significance of LS using ICG fluorescence navigation compared with open segmentectomy (OS). Methods: Eighty-seven patients who underwent anatomical segmentectomies were evaluated for OS (n = 44) and LS (n = 43). The Glissonean pedicle approach was performed using either extra- or intrahepatic method, depending on the location of segment in LS. After clamping pedicle, negative staining method was performed. Liver transection was done along intersegmental plane visualizing by overlay mode of ICG camera. Surgical outcomes were compared between two groups. Correlation between predicted resecting liver volume (PRLV) calculated using volumetry and actual resected liver volume (ARLV) was assessed in two groups. Results: Patients who underwent LS showed better outcomes in operative time, blood loss, and length of hospital stay. There were significantly fewer Grade II and Grade III or higher postoperative complications in LS group. Both values of AST (p < 0.001) and ALT (p < 0.001) on postoperative day 1 were significantly lower in LS group than in OS group. PRLV and ARLV were more strongly correlated in LS (r = 0.896) than in OS (r = 0.773). The difference between PRLV and ARLV was significantly lower in LS group than in OS group (p = 0.022), and this trend was particularly noticeable in posterosuperior segment (p = 0.008) than in anterolateral segment (p = 0.811). Conclusion: LS using ICG navigation allows precise resection and may contribute to safer short-term outcomes than OS, particularly in posterosuperior segment.

Pancreatic cancer and sarcopenia: a narrative review of the current status.

Pancreatic cancer is still a difficult disease to treat, despite recent advances in surgical techniques and chemotherapeutic drugs. Its incidence continues to rise, as does the number of older patients. Sarcopenia is defined as a progressive and generalized loss of skeletal muscle mass and strength. Sarcopenia is present in approximately 40% in patients with pancreatic cancer. Sarcopenia is primarily diagnosed through imaging, and progress is being made in the development of automated methods and artificial intelligence, as well as biomarker research. Sarcopenia has been linked to a poor prognosis in pancreatic cancer patients. However, some studies suggest that sarcopenia is not always associated with a poor prognosis, depending on the resectability of pancreatic cancer and the nature of treatment, such as surgery or chemotherapy. Recent meta-analyses have found that sarcopenia is not linked to postoperative complications. It is still debated whether there is a link between sarcopenia and drug toxicity during chemotherapy. The relationship between sarcopenia and immunity has been investigated, but the mechanism is still unknown.

The Gustave Roussy Immune score is a powerful biomarker for predicting therapeutic resistance to chemotherapy in gastric cancer patients.

PURPOSE: It is highly important to be able to predict the therapeutic efficacy of chemotherapy on patients with unresectable advanced or recurrent gastric cancer (GC). The Gustave Roussy Immune Score (GRIm-s) is a predictor of therapeutic sensitivity to chemotherapy and immune checkpoint inhibitors (ICIs) in other cancers. The present study aimed to analyze the association of the GRIm-s with the therapeutic sensitivity of first-line chemotherapy in GC patients. METHODS: We included 156 patients receiving primary chemotherapy treatment for unresectable or advanced recurrent GC between January 2012 and December 2021 at our institution. We evaluated the correlation between the GRIm-s and therapeutic sensitivities to chemotherapy. The GRIm-s was assessed before the start of first-line chemotherapy. RESULTS: Among the 156 patients, 138 (88.5%) and 18 (11.5%) were classified in the low- and high-risk groups, respectively. The GRIm-s high-risk group was significantly older (p = 0.013), had more advanced unresectable cancer (p = 0.0098), and was significantly less likely to progress to second-line chemotherapy (p = 0.014). The overall survival rate (OS) (p = 0.039) and the progression free survival rate (PFS) (p = 0.017) were significantly worse in the GRIm-s high-risk group. The high GRIm-s was an independent prognostic factor for poor survival in multivariate analysis (p = 0.0094). CONCLUSIONS: Focusing on the GRIm-s before first-line chemotherapy initiation for unresectable advanced or postoperative recurrent GC was useful in predicting the therapeutic resistance to chemotherapy, transition to second-line chemotherapy, and poor prognosis.

Efficacy of Mirogabalin for Taxane-associated Chemotherapy-induced Peripheral Neuropathy in Perioperative Chemotherapy for Early Breast Cancer.

BACKGROUND/AIM: Treatment with taxanes can result in chemotherapy-induced peripheral neuropathy (CIPN). We investigated the efficacy and safety of mirogabalin for the treatment of CIPN in patients who had been administered perioperative chemotherapy including taxane-based agents for breast cancer. PATIENTS AND METHODS: We retrospectively analyzed the case of 43 patients with early breast cancer who received a taxane as perioperative chemotherapy and were administered mirogabalin at the diagnosis of CIPN. RESULTS: Thirty-six patients (83.7%) had grade 1 CIPN and the other seven patients (16.3%) had grade 2 CIPN. The median mirogabalin dose was 10 mg (5-30 mg). CIPN improved from grade 1 to 0 in 12 patients (27.9%) and from grade 2 to 1 in one patient (2.3%); 13 (30.2%) patients thus had an objective therapeutic response. There were no cases in which chemotherapy was reduced or discontinued due to CIPN. Adverse events were evaluated by Common Terminology Criteria for Adverse Events and included five cases of dizziness (11.7%), three of somnolence (7.0%), and two of nausea (4.7%), all of which were grade ≤2. There were no cases of serious (grade ≥3) adverse effects. CONCLUSION: Mirogabalin may be effective and safe for treating CIPN of patients who receive a taxane in a perioperative breast cancer setting.

Risks and Outcomes of Early Dose Reduction in Adjuvant CAPOX Therapy for Colorectal Cancer.

BACKGROUND/AIM: Adjuvant capecitabine and oxaliplatin (CAPOX) therapy is standard strategy for colorectal cancer with risk of recurrence. Early dose reduction (EDR) of CAPOX therapy is commonly used in real-world practice. However, there is limited evidence regarding the effectiveness of CAPOX for patients who had EDR. Therefore, this study aimed to clarify the risks of EDR and its effect on long-term outcomes and body composition factors. PATIENTS AND METHODS: Patients who received CAPOX therapy after radical surgery for colorectal cancer between June 2013 and December 2021 were included. EDR was defined as dose reduction within four courses of CAPOX therapy. Body composition factors were measured for 1 year following surgery to determine the EDR effects. RESULTS: Eighty-four patients were included; 35 (42%) of them had EDR. The multivariate analysis revealed that underweight [odds ratio (OR)=4.95, 95% confidence interval (CI)=1.13-21.7, p=0.03] was a risk factor for EDR. Relapse-free survival (RFS) was significantly better in the non-EDR group (p=0.01). The 5-year RFS rates for the non-EDR and EDR groups were 88.7% and 65.4%, respectively. The multivariate analysis revealed that age >65 years [hazard ratio (HR)=3.97; 95% CI=1.16-13.62, p=0.03] and EDR (HR=7.62; 95% CI=1.71-33.91, p=0.005) were associated with poorer RFS. The 1-year body composition analysis revealed decreases in all factors in the EDR group. CONCLUSION: Preoperative underweight status was associated with EDR, which resulted in decreased RFS and body composition factors when compared with the non-EDR group. Therefore, avoiding EDR and early nutritional intervention after EDR may improve outcomes.

New predictors of microvascular invasion for small hepatocellular carcinoma ≤ 3 cm.

BACKGROUND: Microvascular invasion (MVI) is a risk factor for postoperative recurrence of hepatocellular carcinoma (HCC), even in early-stage HCC. In small HCC ≤ 3 cm, treatment options include anatomical resection or non-anatomical resection, and MVI has a major effect on treatment decisions. We aimed to identify the predictors of MVI in small HCC ≤ 3 cm. METHODS: We retrospectively studied 129 patients with very early or early-stage HCC ≤ 3 cm who had undergone 18F-fluorodeoxyglucose positron emission tomography/computed tomography and subsequent hepatic resection from January 2016 to August 2023. These patients were divided into the derivation cohort (n = 86) and validation cohort (n = 43). We examined the risk factors for MVI using logistic regression analysis, and established a predictive scoring system in the derivation cohort. We evaluated the accuracy of our scoring system in the validation cohort. RESULTS: In the derivation cohort, a Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3), prothrombin induced by vitamin K deficiency or antagonist-II (PIVKA-II), and metabolic tumor volume (MTV) were independent predictors of MVI. We established the scoring system using these three factors. In the validation test, there were no MVI-positive cases with a score of 0 and 1, and all cases were MVI-positive with a score of 4. Moreover, with a score ≥ 2, the sensitivity, specificity, and accuracy of our scoring system were 100%, 71.4%, and 81.4%, respectively. CONCLUSIONS: Our scoring system can accurately predict MVI in small HCC ≤ 3 cm, and could contribute to establishing an appropriate treatment strategy.