Does KRAS mutation status impact the risk of local recurrence after R1 vascular resection for colorectal liver metastasis? An observational cohort study

Liver metastases from colorectal cancer: A joint ESSO-EAHPBA-UEMS core curriculum collaboration

Colorectal liver metastases (CRLM) are a major indication for liver surgery in Europe, highlighting the need for standardized knowledge and training in surgical oncology. The European Society of Surgical Oncology (ESSO) has updated its core curriculum to provide a structured framework for education. Previous publications have addressed pancreatic, hepatocellular, and biliary tract cancers to support candidates preparing for the European Board of Surgery Qualification (EBSQ) exams in Surgical Oncology and Hepato-Pancreato-Biliary Surgery. However, a dedicated guide for CRLM remains absent. This article aims to fill that gap by offering a structured reference on CRLM, covering epidemiology, staging, genetics, and diagnosis of metastatic colorectal cancer. It also outlines multidisciplinary treatment strategies, including systemic, surgical, interventional, and palliative approaches. A structured literature review was conducted using PubMed to identify the most updated (inter)national management guidelines, prioritizing recent multicentre studies, systematic reviews, and meta-analyses published from January 2020 to January 2025. By bridging the gap between the ESSO core curriculum and detailed subspecialty training, this guide provides an essential resource for hepatobiliary surgeons and surgical oncologists. It serves as a valuable tool for those preparing for board examinations while promoting a standardized approach to CRLM education and management across Europe.

The Effect of Hepatic Surgical Margins of Colorectal Liver Metastases on Prognosis: A Systematic Review and Meta-Analysis

Introduction: Colorectal cancer is the third most common malignancy, with around half of patients developing liver metastases. Hepatectomy is the preferred treatment, but its success depends on several factors, including surgical margins. Various surgical margins have been suggested to achieve optimal results. This systematic review and meta-analysis aim to explore the impact of negative surgical margins ranging from 1 to 10 mm, and >10 mm on survival, with the objective of identifying optimal surgical margins. Methods: A systematic literature search was conducted on the MEDLINE, Scopus, and Cochrane databases. The six included studies that examined the effect of surgical margins at the aforementioned distances on patient survival. Studies were assessed for risk of bias using the Quality in Prognosis Studies tool. Statistical analysis was performed using SPSS software. Results: The results of the meta-analysis revealed the superiority of wider surgical margins (>10) on overall survival compared to smaller margins (1-10 mm), as the HR was calculated to be 1.38 [1.10; 1.73]. Specifically, negative margins between 1 and 10 mm are linked to a 38% increased risk of mortality compared to margins larger than 10 mm. The low heterogeneity indicates consistent findings across studies, and the statistically significant hazard ratio underscores the importance of aiming for larger surgical margins to enhance patient outcomes. In the subgroup that included only studies in which patients received neoadjuvant therapy, the HR was 1.48 [1.06; 2.07], further emphasizing the importance of ensuring negative surgical margins in today's era. Conclusions: In summary, this systematic review and meta-analysis highlights the impact of surgical margin width on the survival of patients with colorectal liver metastases, as well as the importance of margin optimization in surgical management strategies.

Initial experience of parenchyma-sparing liver resection with systematic selective hepatic vein reconstruction for colorectal metastases

Objectives

This study aims to assess the feasibility and short-term and intermediate-term technical success rate of the concept of systematic selective hepatic vein (HV) reconstruction for parenchyma-sparing hepatectomies (PSHs) in patients with colorectal liver metastases (CRLM) in accordance with stage 2a of the IDEAL framework.

Design

The prospective case series of patients deemed eligible and operated on according to the concept.

Setting

All patients were treated by a single surgical team in three hospitals in Ukraine from June 2022 to November 2023.

Participants

The study included nine cases of resectable CRLM with at least one lesion located in the hepatocaval confluence with HV(s) invasion, for whom reconstruction of the HV(s) allowed for additional parenchyma preservation, being an alternative to major or extended hepatectomy.

Interventions

Liver resections with different types of HVs reconstruction (primary closure, patching, end-to-end anastomosis with or without grafting) were performed after a thorough evaluation of the future liver remnant volume, volume of potentially additionally preserved parenchyma and possibility of future repeat hepatectomies.

Main outcome measures

Postoperative morbidity, short-term and long-term patency of the reconstructed vessels, and the volume of additionally preserved parenchyma were the focus.

Results

Segmental resection was performed in four cases, two with graft interposition. Patch reconstruction was performed for three HVs and two inferior vena cava resections. Two cases required primary closure. No mortality was observed, while the major morbidity rate was 33%. The short-term and long-term patency of the reconstructed HVs was 88.9% and 66.7%, respectively. HV reconstructions allowed the preservation of additional parenchyma (mean 495.4 mL, 95% CI 350.2 to 640.7). A decision-making algorithm to be used within the described approach is proposed.

Conclusions

Selective HV reconstruction is a feasible approach for PSH for CRLM. Further studies are needed to compare this approach to convenient major hepatectomies.

Critical appraisal of surgical margins according to KRAS status in liver resection for colorectal liver metastases: Should surgical strategy be influenced by tumor biology?

BACKGROUND

KRAS mutation is a negative prognostic factor for colorectal liver metastases. Several studies have investigated the resection margins according to KRAS status, with conflicting results. The aim of the study was to assess the oncologic outcomes of R0 and R1 resections for colorectal liver metastases according to KRAS status.

METHODS

All patients who underwent resection for colorectal liver metastases between 2010 and 2015 with available KRAS status were enrolled in this multicentric international cohort study. Logistic regression models were used to investigate the outcomes of R0 and R1 colorectal liver metastases resections according to KRAS status: wild type versus mutated. The primary outcomes were overall survival and disease-free survival.

RESULTS

The analysis included 593 patients. KRAS mutation was associated with shorter overall survival (40 vs 60 months; P = .0012) and disease-free survival (15 vs 21 months; P = .003). In KRAS-mutated tumors, the resection margin did not influence oncologic outcomes. In multivariable analysis, the only predictor of disease-free survival and overall survival was primary tumor location (P = .03 and P = .03, respectively). In KRAS wild-type tumors, R0 resection was associated with prolonged overall survival (74 vs 45 months, P < .001) and disease-free survival (30 vs 17 months, P < .001). The multivariable model confirmed that R0 resection margin was associated with prolonged overall survival (hazard ratio = 1.43, 95% confidence interval: 1.01-2.03) and disease-free survival (hazard ratio = 1.42; 95% confidence interval: 1.06-1.91).

CONCLUSIONS

KRAS-mutated colorectal liver metastases showed more aggressive tumor biology with inferior overall survival and disease-free survival after liver resection. Although R0 resection was not associated with improved oncologic outcomes in the KRAS-mutated tumors group, it seems to be of paramount importance for achieving prolonged long-term survival in KRAS wild-type tumors.

The association between KRAS and histopathological growth patterns and the impact on resection margins around vasculature and bile ducts in colorectal liver metastases

The liver is the most frequent and often the only site of distant disease in colorectal cancer and, of all treatment protocols currently in use, resection is the most likely to result in long-term cure. Within the liver, tumour proximity to major vasculature and biliary structures poses a resection challenge, requiring a balance of achieving negative margins while preserving adequate vascular circulation and biliary drainage. The focus on parenchymal sparing resections are important but just as important may be the 'biological' behaviour of the tumour. In colorectal liver metastases (CRLM), biomarkers such as the Kirsten rat sarcoma oncogene homologue (KRAS) gene and histological growth patterns (HGPs) further improve the prognostication after resection. However, to date, the association between the KRAS status and HGPs in CRLM and their impact on resection margins around major vasculature or biliary structures in terms of overall survival and recurrence rates are unclear. The aim of this review was to explore the available evidence for the association between KRAS and HGPs in CRLM and attempt to define their impact on resection margins near major structures.

Is Precision Surgery Applicable to Colorectal Liver Metastases? A Systematic Review and Meta-analysis of Studies that Investigate the Association of Surgical Technique with Outcomes in the Context of Distinct Tumor Biology

BACKGROUND

Although some data suggest that patients with mutRAS colorectal liver metastases (CRLM) may benefit from anatomic hepatectomy, this topic remains controversial. We performed a systematic review and meta-analysis to determine whether RAS mutation status was associated with prognosis relative to surgical technique [anatomic resection (AR) vs. nonanatomic resection (NAR)] among patients with CRLM.

PATIENTS AND METHODS

A systematic review and meta-analysis of studies were performed to investigate the association of AR versus NAR with overall and liver-specific disease-free survival (DFS and liver-specific DFS, respectively) in the context of RAS mutation status.

RESULTS

Overall, 2018 patients (831 mutRAS vs. 1187 wtRAS) were included from five eligible studies. AR was associated with a 40% improvement in liver-specific DFS [hazard ratio (HR) = 0.6, 95% confidence interval (CI) 0.44-0.81, p = 0.01] and a 28% improvement in overall DFS (HR = 0.72, 95% CI 0.54-0.95, p = 0.02) among patients with mutRAS tumors; in contrast, AR was not associated with any improvement in liver-specific DFS or overall DFS among wtRAS patients. These differences may have been mediated by the 40% decreased incidence in R1 resection among patients with mutRAS tumors who underwent AR versus NAR [relative risk (RR): 0.6, 95% CI 0.40-0.91, p = 0.02]. In contrast, the probability of an R1 resection was not decreased among wtRAS patients who underwent AR versus NAR (RR: 0.93, 95% CI 0.69-1.25, p = 0.62).

CONCLUSIONS

The data suggest that precision surgery may be relevant to CRLM. Specifically, rather than a parenchymal sparing dogma for all patients, AR may have a role in individuals with mutRAS tumors.

Multimodal Management of Colorectal Liver Metastases: State of the Art

Liver is the most common site of colorectal cancer (CRC) metastases. Treatment of CRC liver metastases (CRLM) includes different strategies, prevalently based on the clinical and oncological intent. Valid approaches in liver-limited or liver-prevalent disease include surgery, percutaneous ablative procedures (radiofrequency ablation, microwave ablation), intra-arterial perfusional techniques (chemo-embolization, radio-embolization) as well as stereotactic radiotherapy. Systemic treatments, including chemotherapy, immunotherapy and other biological agents, are the only options for patients with no chance of locoregional approaches. The use of chemotherapy in other settings, such as neoadjuvant, adjuvant or conversion therapy of CRLM, is commonly accepted in the clinical practice, although data from several clinical trials have been mostly inconclusive. The optimal integration of all these strategies, when applicable and clinically indicated, should be ever considered in patients affected by CRLM based on clinical evidence and multidisciplinary experience. Here we revised in detail all the possible therapeutic approaches of CRLM focusing on the current evidences, the studies still in progress and the often contradictory data.

Does RAS Status Increase the Prevalence of Positive Resection Margin in Colorectal Liver Metastasis? A Systematic Review and Meta-Analysis

BACKGROUND

Colorectal liver metastasis has a high incidence, and RAS oncogene mutation status carries significant prognostic information. We aimed to assess whether RAS-mutated patients present more or less frequently with positive margins in their hepatic metastasectomy.

METHODS

We performed a systematic review and meta-analysis of studies from PubMed, Embase, and Lilacs databases. We analyzed liver metastatic colorectal cancer studies, which included information on RAS status and had surgical margin analysis of the liver metastasis. Odds ratios were computed using a random-effect model due to anticipated heterogeneity. We further performed a subanalysis limited to studies that included only patients with KRAS instead of all-RAS mutations.

RESULTS

From the 2,705 studies screened, 19 articles were included in the meta-analysis. There were 7,391 patients. The prevalence of positive resection margin was not significantly different between patients carrier vs non-carrier for the all-RAS mutations (OR .99; 95% CI 0.83-1.18; P = .87), and for only KRAS mutation (OR .93; 95% CI 0.73-1.19; P = .57).

CONCLUSIONS

Despite the strong correlation between colorectal liver metastasis prognosis and RAS mutation status, our meta-analysis's results suggest no correlation between the RAS status and the prevalence of positive resection margins. The findings contribute to a better understanding of the RAS mutation's role in the surgical resections of colorectal liver metastasis.

Prognostic Impact of Surgical Margin Width in Hepatectomy for Colorectal Liver Metastasis

As for resection for colorectal liver metastasis (CRLM), securing an adequate surgical margin is important for achieving a better prognosis. However, it is often difficult to achieve adequate margins for the resection of CRLM. So the current survival impact of sub-centi/millimeter surgical margins in hepatectomy for CRLM should be evaluated. In the current era of multidisciplinary treatment options, this review focused on the prognostic impact of a sub-centi/millimeter surgical margin width in hepatectomy for CRLM. We systematically reviewed retrospective studies that clearly described the surgical margin width for hepatectomy for CRLM. We selected studies conducted since 2000 that involved patients diagnosed as having CRLM. We focused on studies that investigated not only surgical margins, but also microscopic surgical curability such as R0 (microscopically complete resection) or R1 (microscopically incomplete resection), which clearly describe their definitions. Based on our literature review, 1, 2, or 5 mm was considered the minimum surgical margin width for hepatectomy for CRLM. Although a surgical margin width of 1 mm is acceptable for hepatectomy for CRLM, submillimeter margins, which are defined as R1 in many reports, are only acceptable for limited patients such as those who have undergone preoperative chemotherapy. Zero-mm margins are also acceptable in limited patients such as those who show a good response to preoperative chemotherapy. New chemotherapy agents have been reported to reduce the prognostic impact of a narrow surgical margin width. The incidence of margin recurrence, which is a major concern regarding R1 resection of CRLM, is about 20-30% according to the majority of earlier reports. As evaluations of the actual prognostic impact of the surgical margin remain difficult, further study is warranted.

Prognostic impact of R1 resection margin in synchronous and simultaneous colorectal liver metastasis resection: a retrospective cohort study

BACKGROUND

A margin ≥ 1 mm is considered a standard resection margin for colorectal liver metastasis (CRLM). However, microscopic incomplete resection (R1) is not rare since aggressive surgical resection has been attempted in multiple and bilobar CRLM. This study aimed to investigate the prognostic impact of resection margins and perioperative chemotherapy in patients with CRLM.

METHODS

A total of 368 of 371 patients who underwent simultaneous colorectal and liver resection for synchronous CRLM between 2006 and June 2017, excluding three R2 resections, were included in this study. R1 resection was defined as either abutting tumor on the resection line or involved margin in the pathological report. The patients were divided into R0 (n = 304) and R1 (n = 64) groups. The clinicopathological characteristics, overall survival, and intrahepatic recurrence-free survival were compared between the two groups using propensity score matching.

RESULTS

The R1 group had more patients with ≥ 4 liver lesions (27.3 vs. 50.0%, P < 0.001), higher mean tumor burden score (4.4 vs. 5.8%, P = 0.003), and more bilobar disease (38.8 vs. 67.2%, P < 0.001) than the R0 group. Both R0 and R1 groups showed similar long-term outcomes in the total cohort (OS, P = 0.149; RFS, P = 0.414) and after matching (OS, P = 0.097, RFS: P = 0.924). However, the marginal recurrence rate was higher in the R1 group than in the R0 group (26.6 vs. 16.1%, P = 0.048). Furthermore, the resection margin did not have a significant impact on OS and RFS, regardless of preoperative chemotherapy. Poorly differentiated, N-positive stage colorectal cancer, liver lesion number ≥ 4, and size ≥ 5 cm were poor prognostic factors, and adjuvant chemotherapy had a positive impact on survival.

CONCLUSIONS

The R1 group was associated with aggressive tumor characteristics; however, no effect on the OS and intrahepatic RFS with or without preoperative chemotherapy was observed in this study. Tumor biological characteristics, rather than resection margin status, determine long-term prognosis. Therefore, aggressive surgical resection should be considered in patients with CRLM expected to undergo R1 resection in this multidisciplinary approach era.

The Impact of KRAS Status on the Required Surgical Margin Width for Colorectal Liver Metastasis Resection

Local recurrence after colorectal liver metastasis (CRLM) resection severely affects survival; however, the required surgical margin width remains controversial. This study investigated the impact of KRAS status on surgical margin width and local recurrence rate (LRR) post-CRLM resection. Overall, 146 resected CRLMs with KRAS status (wild-type KRAS (wtKRAS): 98, KRAS mutant (mKRAS): 48) were included. The LRR for each group, R1 (margin positive) and R0 (margin negative), was analyzed by KRAS status. R0 was further stratified into Ra (margin ≥ 5 mm) and Rb (margin < 5 mm). Patients with local recurrence had significantly worse 5-year overall survival than those without local recurrence (p = 0.0036). The mKRAS LRR was significantly higher than wtKRAS LRR (p = 0.0145). R1 resection resulted in significantly higher LRRs than R0 resection for both wtKRAS and mKRAS (p = 0.0068 and p = 0.0204, respectively), and while no significant difference was observed in the Ra and Rb LRR with wtKRAS, the Rb LRR with mKRAS (33.3%) was significantly higher than Ra LRR (5.9%) (p = 0.0289). Thus, R0 resection is sufficient for CRLM with wtKRAS; however, CRLM with mKRAS requires resection with a margin of at least 5 mm to prevent local recurrence.

Liver Transplantation for Hepatic Metastases from Colorectal Cancer: Current Knowledge and Open Issues

More than 40% of patients with colorectal cancer present liver metastases (CRLM) during the course of their disease and up to 50% present with unresectable disease. Without surgical interventions, survival for patients treated with systemic therapies alone is dismal. In the past, liver transplantation (LT) for patients with unresectable CRLM failed to show any survival benefit due to poor selection, ineffective chemotherapeutic regimens, unbalanced immunosuppression and high perioperative mortality. Since then and for many years LT for CRLM was abandoned. The turning point occurred in 2013, when the results from the Secondary Cancer (SECA I) pilot study performed at Oslo University were published reporting a 60% 5-year overall survival after LT in patients with unresectable CRLM. These results effectively reignited the interest in LT as a potential therapy for CRLM, and several trials are undergoing. The aims of this article are to give a comprehensive overview of the available evidence on LT for CRLM, discuss the open issues in this rapidly evolving field, and highlight possible ways to address the future of this fascinating therapeutic alternative for selected patients with CRLM.

Colorectal Cancer Liver Metastases: Is an R1 Hepatic Resection Accepted?

Metastatic colorectal cancer is associated with a rather dismal 5-year overall survival. The liver is the most commonly affected organ. Improved 5-year survival rates after successful hepatic resections for metastases confined to the liver have been reported. Certainly, a hepatectomy that results in an incomplete tumor resection, in terms of leaving macroscopic residual tumor in the future liver remnant, is not associated with survival benefits. However, the prognostic implications of a microscopically positive surgical margin or a clear margin of less than 1 mm (R1) on pathology are debatable. Although it has been a field of extensive research, the relevant literature often reports contradictory results. The purpose of the present study was to define, assess the risk factors for, and, ultimately, analyze the effect that an R1 hepatic resection for colorectal cancer liver metastases might have on local recurrence rates and long-term prognosis by reviewing the relevant literature. Achieving an R0 hepatic resection, optimally with more than 1 mm of clear margin, should always be the goal. However, in the era of the aggressive multimodality treatment of liver metastatic colorectal cancer, an R1 resection might be the cost of increasing the pool of patients finally eligible for resection. The majority of literature reports have highlighted the detrimental effect of R1 resections on local recurrence and overall survival. However, there are indeed studies that degraded the prognostic handicap as a consequence of an R1 resection in selected patients and highlighted the presence of RAS mutations, the response to chemotherapy, and, in general, factors that reflect the biology of the disease as important, if not the determinant, prognostic factors. In these patients, the aggressive disease biology seems to outperform the resection margin status as a prognostic factor, and the recorded differences between R1 and R0 resections are equalized. Properly and accurately defining this patient group is a future challenge in the field of the surgical treatment of colorectal cancer liver metastases.

Implications of RAS Mutations on Oncological Outcomes of Surgical Resection and Thermal Ablation Techniques in the Treatment of Colorectal Liver Metastases

Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer-related death. More than 50% of patients with CRC will develop liver metastases (CRLM) during their disease. In the era of precision surgery for CRLM, several advances have been made in the multimodal management of this disease. Surgical treatment, combined with a modern chemotherapy regimen and targeted therapies, is the only potential curative treatment. Unfortunately, 70% of patients treated for CRLM experience recurrence. RAS mutations are associated with worse overall and recurrence-free survival. Other mutations such as BRAF, associated RAS /TP53 and APC/PIK3CA mutations are important genetic markers to evaluate tumor biology. Somatic mutations are of paramount interest for tailoring preoperative treatment, defining a surgical resection strategy and the indication for ablation techniques. Herein, the most relevant studies dealing with RAS mutations and the management of CRLM were reviewed. Controversies about the implication of this mutation in surgical and ablative treatments were also discussed.

Infiltrative Tumor Borders in Colorectal Liver Metastasis: Should We Enlarge Margin Size?

BACKGROUND

Surgery is the only potentially curative treatment for colorectal cancer liver metastases (CRLMs). Despite an improvement in results following resection, recurrence rates remain high. Many histopathological features have been reported as prognostic factors. Infiltrative borders are known to be associated with worse prognosis; however, margin size has never been evaluated together with the type of tumor border. In the present study, we analyzed the prognosis of patients with resected CRLM according to tumor growth pattern (TGP) and whether a larger margin size would bring any prognostic benefit.

PATIENTS AND METHODS

Medical records from a prospective database of 645 patients who underwent hepatic resection for CRLM between January 2004 and December 2019 at a single center were reviewed, and 266 patients were included in the analytic cohort. TGP (pushing or infiltrative) was evaluated regarding the impact in overall and disease-free survival. The impact of margin size (≤ or > 1 cm) on survival and hepatic recurrence according to TGP was also evaluated.

RESULTS

TGP was defined as infiltrative in 182 cases (68.4%) and pushing in 84 patients (31.6%). Patients with infiltrative-type border presented worse overall survival and disease-free survival, as well as higher intrahepatic recurrence (p < 0.05). Larger margin size did not impact the prognosis of patients with infiltrative borders.

CONCLUSIONS

Patients with infiltrative-type border present worse prognosis and higher intrahepatic recurrence. Larger margin size (> 1 cm) does not change the prognosis in patients with infiltrative border, showing that tumor biology is the most important factor for survival.

Relevance of chemotherapy and margin status in colorectal liver metastasis

PURPOSE

This retrospective, single-center study aimed to investigate the importance of chemotherapy and to come up with the optimal liver resection margin length for patients with resectable colorectal liver metastasis (CRLM).

METHODS

Patients who had undergone any form of liver resection for CRLM were reviewed and analyzed. The analyses were broken down into three parts: (1) overall effect of chemotherapy, (2) effect of chemotherapy with positive/negative resection margin, and (3) result of discriminative analysis with optimal margin length analysis.

RESULTS

In total, 381 patients were studied. Among them, 279 received chemotherapy whereas 102 did not. Survival was significantly better in patients with chemotherapy (5-year, 43.6% vs. 25.8%) (p < 0.001). Patients who received chemotherapy (n = 93) with negative margins had better survival than patients (n = 8) with positive margins (5-year, 28.1% vs. 0%) (p = 0.019). On multivariate analysis, margin involvement was the poor prognostic factor for survival. Patients who had chemotherapy (n = 238) with negative margin showed a trend of better survival than patients (n = 41) with positive margins (5-year, 45.7% vs. 29.3%) (p = 0.085). Patients (n = 93) with negative margin and no chemotherapy and patients (n = 41) with positive margin and chemotherapy had comparable survival at 5 years (p = 0.422). On multivariate analysis, tumor number was the prognostic factor for survival. By the discriminant method, 1.09 cm (sensitivity 0.242, specificity 0.718) was determined as the cut-off for optimal margin length. Patients who had margin ≥ 1.09 cm (n = 81) enjoyed significantly better survival (5-year, 54.3% vs. 33.5%) (p = 0.041). On multivariate analysis, margin length ≥ 1.09 cm was the prognostic factor for favorable survival.

CONCLUSION

The results demonstrated the important effect of perioperative chemotherapy and negative margin liver resection in management of patients suffered from CRLM.

Identification of Glisson's Capsule Invasion During Hepatectomy for Colorectal Liver Metastasis by Contrast-Enhanced Ultrasonography Using Perflubutane

BACKGROUND

Glisson invasion by CLM is associated with a risk of margin-positive resection, leading to poor long-term outcomes after hepatectomy. This study was performed to evaluate the efficacy of intraoperative ultrasonography (IOUS) for the diagnosis of Glisson's capsule invasion by colorectal liver metastasis (CLM).

METHODS

This prospective study involved 50 consecutive patients undergoing hepatectomy for CLM. Preoperatively, all patients had undergone gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (EOB-MRI). During hepatectomy, a contrast agent (perflubutane) was intravenously injected and Glisson invasion was estimated based on three characteristic findings: a tumor thrombus, peripheral dilatation, and border irregularity/caliber change. The diagnostic abilities of the preoperative and intraoperative imaging studies were evaluated based on pathological examinations of resected specimens.

RESULTS

Among 187 CLMs resected, pathological examinations proved Glisson invasion in 24 tumors (13%). IOUS revealed a tumor thrombus in 3 tumors (1.6%), peripheral dilatation in 4 (2.1%), and border irregularity and/or caliber change in 24 (12.8%). The sensitivity and specificity of IOUS with any of the above three findings for diagnosis of Glisson invasion was 79% and 96%, respectively, while preoperative EOB-MRI detected Glisson invasion in only four tumors (sensitivity/specificity, 17%/100%). The cutoff value of caliber change for diagnosis of Glisson invasion was set at 140% by receiver operating characteristic analysis. The R0 resection rates were not significantly different between patients with (82%) and without (85%) Glisson invasion.

CONCLUSIONS

Identification of characteristic findings (tumor thrombus, peripheral dilatation, and border irregularity/caliber change) by contrast-enhanced IOUS is useful for the prediction of Glisson invasion by CLM.