Ablation Of Colorectal Liver Metastases Research Articles

Multicenter and inter-software evaluation of ablative margins after thermal ablation of colorectal liver metastases.

To assess the association between minimal ablative margin (MAM) and local tumor progression (LTP) following CT-guided thermal ablation of colorectal liver metastases (CRLM) in a multicenter cohort and across two confirmation software. This multicenter retrospective study included patients who underwent CT-guided radiofrequency or microwave ablation for CRLM between 2009 and 2021 in three institutions. Three-dimensional (3D) MAM was retrospectively assessed using dedicated ablation confirmation software by automatic non-rigid (Ablation-fit) or semi-automatic rigid co-registration (SAFIR) of intraprocedural pre- and post-ablation contrast-enhanced CT scans by two independent reader teams blinded to patient outcomes. LTP was assessed on a per-tumor basis. Factors associated with LTP-free survival were assessed using multivariable Cox regression analysis. Overall, 113 patients (mean age: 67 ± 10 years; 78 men) who underwent thermal ablation for 189 CRLM (mean diameter: 1.9 ± 1.1 cm) met the inclusion criteria. 173/189 (92%) CRLM could be successfully analyzed using both software. Over a median follow-up of 31 months (IQR: 22-47), 21 of 173 CRLM (12.1%) developed LTP. On multivariable analysis, 3D MAM was independently associated with LTP in both software (Ablation-fit: HR 0.47, 95% CI: 0.36-0.61, p < 0.001; SAFIR: HR 0.42, 95% CI: 0.32-0.55, p < 0.001). No LTP was observed in CRLM ablated with MAM ≥ 4 mm (Ablation-fit) and ≥ 5 mm (SAFIR). The per-tumor median absolute difference in MAM quantification between both software was 2 mm (IQR: 1-3). MAM was independently associated with LTP after thermal ablation of CRLM across multicenter data and two confirmation software. Ablations achieving a MAM ≥ 5 mm were associated with local control in both software. MAMs from intraprocedural contrast-enhanced CT were independently associated with LTP after thermal ablation of CRLM across multicenter data and two confirmation software, with a margin ≥ 5 mm associated with local control in both software. Sufficient ablative margins are critical for local control following thermal ablation of CRLM. Intraprocedural CT-derived MAM was the only independent factor associated with LTP across two confirmation software. No LTP was observed in CRLM ablated with a MAM ≥ 5 mm.

Microwave ablation for colorectal liver metastases with ultrasound fusion imaging assistance: a stratified analysis study based on tumor size and location.

To investigate the efficacy of ultrasound fusion imaging-assisted microwave ablation (MWA) for patients with colorectal liver metastases (CRLM) based on stratified analysis of tumor size and location. Patients with CRLM who underwent ultrasound fusion imaging-assisted MWA in our hospital between February 2020 and February 2023 were enrolled into this retrospective study. Ultrasound fusion imaging was used for detection, guidance, monitoring and immediate evaluation throughout the MWA procedures. Technical success, technique efficacy, local tumor progression (LTP), intrahepatic progression and overall survival (OS) were recorded and analyzed. The subgroup analysis of intrahepatic progression of MWA for CRLM was performed according to tumor size and location. A total of 51 patients with 122 nodules were enrolled. Both technical success and technique efficacy were acquired in all nodules. In a median follow-up period of 19months, 2.5% of the nodules (3/122) were observed LTP. The 1-year and 2-year cumulative intrahepatic progression rates were 38.7% and 52.1% respectively. Patients were divided into subgroups according to tumor size (≥ 30mm, n = 13; < 30mm, n = 38) and tumor location (perivascular, n = 20; non-perivascular, n = 31 and subcapsular, n = 36; non-subcapsular, n = 15). The cumulative intrahepatic progression rates were similar between the subgroups regarding tumor size and perivascular location, while significantly higher in the subcapsular group than in the non-subcapsular group (p = 0.021). Ultrasound fusion imaging-assisted MWA exhibited satisfactory local efficacy for CRLM, especially for non-subcapsular tumors.

Achievement of textbook outcome after hepatectomy combined with thermal ablation for colorectal liver metastases.

Hepatic resection combined with intraoperative ablation has been described as a technical solution potentially widening the resectability rate of patients with colorectal liver metastases (CRLM). Nevertheless, the perioperative and oncological benefit provided by this combined approach remains unclear. We hypothesized that textbook outcome (TO), which is a composite measure achieved for patients for whom some desired health indicators are met, may help to refine the indications of this approach. Patients submitted to hepatectomy with curative intent in combination with radiofrequency ablation or microwave ablation for CRLM≤3cm in two tertiary referral centers were included. TO was defined according to a recent definition for liver surgery based on a Delphi process including also the achievement of complete radiological response of the ablated lesion/s at 4weeks. Between 2015 and 2022, 112 patients were enrolled. Among them, 63 (56.2%) achieved a TO. According to multivariate analysis, minimally invasive (MI) approach (OR 2.72, 95% CI 0.99-7.48, p=0.050), simultaneous CR resection (OR 0.28, 95% CI 0.11-0.70, p=0.007), tumor burden score (OR 0.89, 95% CI 0.82-0.96, p=0.004), and major hepatectomy (OR 0.12, 95% CI 0.03-0.52, p=0.004) were significantly associated with the achievement of TO. Median overall survival was longer in those patients who were able to achieve a TO compared to those who did not. The combination of hepatectomy and ablation constitutes a valuable solution in patients affected by multiple CRLM and it may provide, also using a MI approach, adequate perioperative and oncological outcomes, allowing to achieve TO, however, in a selected number of patients and depending on several factors including the burden of disease.

CT versus MR guidance for radiofrequency ablation in patients with colorectal liver metastases: a 10-year follow-up favors MR guidance.

To compare the results of CT- vs MR-guided radiofrequency ablation (RFA) of liver metastases (LM) from colorectal cancer after 10years of follow-up in an observational, retrospective, and multicentric study. A total of 238 patients with 496 LM were treated with RFA either with CT (CT group) or magnetic resonance (MR group) guidance. Every ablated LM was assessed and followed up with diagnostic MRI. Technical success, technique efficacy, predictive factors, recurrence rates, and overall survival were assessed. The CT group comprised 143 patients and the MR group 77 patients. Eighteen patients underwent ablation with both modalities. Technical success per patient and per lesion was 88% and 93% for CT and 87% and 89.6% for MR, and technique efficacy was 97.1% and 98.6% for CT and 98.7% and 99.3% for MR respectively. Local recurrence following the first ablation (primary patency) occurred in 20.1% (CT) vs 4.6% (MR) (p < 0.001). Residual liver tumor, size of LM, and advanced N and M stage at initial diagnosis were independent predictors for overall survival in both groups. The median overall survival measured from first RFA treatment was 2.6years. The 1-year, 5-year, and 10-year survival were 85.9%, 25.5%, and 19.1% respectively. The MR group had significantly better local control compared to the CT group. There was no significant difference in patient survival between the two groups. MR-guided radiofrequency ablation of colorectal liver metastases is safe and effective, and offers better local control than CT-guided ablation. • Imaging modality for radiofrequency ablation guidance is an independent predictor of local recurrence in colorectal liver metastases. • MR-guided radiofrequency ablation achieved better local control of liver metastases from colorectal cancer than CT-guided. • The number and size of liver metastases are, among others, independent predictors of survival. Radiofrequency ablation with MR guidance improved clinical outcome but does not affect survival.

Independent validation of CT radiomics models in colorectal liver metastases: predicting local tumour progression after ablation

ObjectivesIndependent internal and external validation of three previously published CT-based radiomics models to predict local tumor progression (LTP) after thermal ablation of colorectal liver metastases (CRLM).Materials and methodsPatients with CRLM treated with thermal ablation were collected from two institutions to collect a new independent internal and external validation cohort. Ablation zones (AZ) were delineated on portal venous phase CT 2–8 weeks post-ablation. Radiomics features were extracted from the AZ and a 10 mm peri-ablational rim (PAR) of liver parenchyma around the AZ. Three previously published prediction models (clinical, radiomics, combined) were tested without retraining. LTP was defined as new tumor foci appearing next to the AZ up to 24 months post-ablation.ResultsThe internal cohort included 39 patients with 68 CRLM and the external cohort 52 patients with 78 CRLM. 34/146 CRLM developed LTP after a median follow-up of 24 months (range 5–139). The median time to LTP was 8 months (range 2–22). The combined clinical-radiomics model yielded a c-statistic of 0.47 (95%CI 0.30–0.64) in the internal cohort and 0.50 (95%CI 0.38–0.62) in the external cohort, compared to 0.78 (95%CI 0.65–0.87) in the previously published original cohort. The radiomics model yielded c-statistics of 0.46 (95%CI 0.29–0.63) and 0.39 (95%CI 0.28–0.52), and the clinical model 0.51 (95%CI 0.34–0.68) and 0.51 (95%CI 0.39–0.63) in the internal and external cohort, respectively.ConclusionThe previously published results for prediction of LTP after thermal ablation of CRLM using clinical and radiomics models were not reproducible in independent internal and external validation.Clinical relevance statementLocal tumour progression after thermal ablation of CRLM cannot yet be predicted with the use of CT radiomics of the ablation zone and peri-ablational rim. These results underline the importance of validation of radiomics results to test for reproducibility in independent cohorts.Key Points• Previous research suggests CT radiomics models have the potential to predict local tumour progression after thermal ablation in colorectal liver metastases, but independent validation is lacking.• In internal and external validation, the previously published models were not able to predict local tumour progression after ablation.• Radiomics prediction models should be investigated in independent validation cohorts to check for reproducibility.Graphical

Combined hepatic resection and ablation for high burden of colorectal liver metastases demonstrates safety and durable survival

BackgroundHepatic resection (HR) and thermal ablation of Colorectal Liver Metastases (CRLM) have each individually demonstrated safety and survival benefit. We sought to provide our experience with the combination of HR + ablation within one operation for patients with multiple CRLM. MethodsReview of a single institution database of patients who underwent HR + ablation between 2010 and 2019. Results161 patients were identified who underwent HR + ablation for isolated CRLM (mean age: 59, male 63.4%). 125 (77.6%) patients had bilobar disease and 92 (57.1%) patients had ≥5 tumors. 28 (17.4%) patients experienced minor (grade 1 or 2) complications while 20 (12.4%) had grade 3–5 complications. Patients who underwent simultaneous colon resection with HR + ablation had a higher complication rate (22 of 47, 46.8%) than those undergoing HR + ablation only (26 of 114, 22.8%, p = 0.002). Median and 5-year OS for all patients undergoing HR + ablation was 38.2 months and 33.2%, respectively. 5-year hepatic recurrence free survival was 23.5%. Patients with 5 or more tumors demonstrated no difference in median survival compared to those with fewer than 5 tumors (37.0 months vs 38.4 months, p = 0.326). ConclusionsIn this population of CRLM patients with a relatively high burden of disease, HR + ablation demonstrated an acceptable safety profile as well as durable long-term survival.

Hepatic arterial oxaliplatin plus intravenous 5-fluorouracil and cetuximab for first-line treatment of colorectal liver metastases: A multicenter phase II trial

BackgroundThe efficacy and tolerability of hepatic arterial infusion (HAI) oxaliplatin plus systemic 5-fluorouracil and cetuximab as frontline treatment in patients with colorectal liver metastases (CRLM) are unknown. MethodsIn this multicenter, single-arm phase II study, patients with CRLM not amenable to curative-intent resection or requiring complex/major liver resection, and no prior chemotherapy for metastatic disease, received HAI oxaliplatin and intravenous 5-fluorouracil, leucovorin and cetuximab, every two weeks until disease progression, limiting toxicity or at least 3 months after complete response or curative-intent resection/ablation. The primary endpoint was overall response rate (ORR). Results35 patients, mostly with bilateral (89%), multiple CRLM (>4, 86%; >10, 46%) were enrolled in eight centers. The ORR was 88% (95% CI, 71%−96%) among evaluable patients (n = 32), and 95% (95% CI 70–100%) among the 22 wild-type RAS/BRAF evaluable patients. After a median follow-up of 8.8 years (95% CI, 8.7-not reached), median progression-free survival was 17.9 months (95% CI, 15–23) and median overall survival (OS) was 46.3 months (95% CI, 40.0-not reached). 23 of the 35 patients (66%), including 22 (79%) of the 25 patients with wild-type RAS tumor, underwent curative-intent surgical resection and/or ablation of CRLM. HAI catheter remained patent in 86% of patients, allowing for a median of eight oxaliplatin infusions (range, 1–19). Treatment toxicity was manageable, without toxic death. ConclusionHAI oxaliplatin plus systemic 5-fluorouracil and cetuximab appears highly effective in the frontline treatment of patients with unresectable CRLM and should be investigated further.

Percutaneous ablation of colorectal liver metastases: a comparison between the outcomes of grayscale US guidance and Sonazoid CEUS Kupffer phase guidance using propensity score matching

Purpose To assess the utility of Sonazoid contrast-enhanced ultrasound (CEUS) for guiding percutaneous microwave ablation (MWA) for colorectal liver metastases (CRLMs). Materials and Methods The medical records of patients who had undergone ultrasound (US)-guided percutaneous MWA between July 2020 and June 2022, were reviewed. Propensity score matching (PSM) with a ratio of 1:1 was used to balance the potential bias between the grayscale US-guided and Sonazoid CEUS-guided groups. Local tumor progression (LTP), intrahepatic recurrence (IR), and complication rates were compared between the two groups. Results Of 252 patients enrolled, 247 achieved complete ablation, and the technical effectiveness was 98.0% (247/252). Of these 247 patients, 158 were in the grayscale US-guided group and 89 in the Sonazoid CEUS-guided group. The median follow-up period was 14.6 months. After PSM, there were no significant differences in LTP, IR, or complication rates between the two groups (p = 0.100, p = 0.511, p > 0.99, respectively). Multivariate analysis identified tumor size ≥ 3 cm (hazard ratio [HR], 7.945; 95% CI, 2.591-24.370; p < 0.001), perivascular (HR, 2.331; 95% CI, 1.068-5.087; p = 0.034), and tumor depth > 8 cm (HR, 3.194; 95% CI, 1.439-7.091; p = 0.004) as significant factors associated with LTP. For tumors with poor vision on grayscale US, Sonazoid CEUS-guided ablation achieved a better LTP rate than grayscale US-guided ablation (3.7% vs.14.8%, p = 0.032). Conclusion For tumors with poor vision on grayscale US, Sonazoid CEUS guidance is recommended for better local tumor control.

ASO Visual Abstract: Rates and Patterns of Recurrence After Microwave Ablation of Colorectal Liver Metastases: A per-Lesion Analysis of 416 Tumors in the Era of 2.45 GHz Generators.

ASO Visual Abstract: Rates and Patterns of Recurrence After Microwave Ablation of Colorectal Liver Metastases: A per-Lesion Analysis of 416 Tumors in the Era of 2.45 GHz Generators.

Trends and overall survival after combined liver resection and thermal ablation of colorectal liver metastases: a nationwide population-based propensity score-matched study

BackgroundIn colorectal liver metastases (CRLM) patients, combination of liver resection and ablation permit a more parenchymal-sparing approach. This study assessed trends in use of combined resection and ablation, outcomes, and overall survival (OS). MethodsThis population-based study included all CRLM patients who underwent liver resection between 2014 and 2022. To assess OS, data was linked to two databases containing date of death for patients treated between 2014 and 2018. Hospital variation in the use of combined minor liver resection and ablation versus major liver resection alone in patients with 2–3 CRLM and ≤3 cm was assessed. Propensity score matching (PSM) was applied to evaluate outcomes. ResultsThis study included 3593 patients, of whom 1336 (37.2%) underwent combined resection and ablation. Combined resection increased from 31.7% in 2014 to 47.9% in 2022. Significant hospital variation (range 5.9–53.8%) was observed in the use of combined minor liver resection and ablation. PSM resulted in 1005 patients in each group. Major morbidity was not different (11.6% vs. 5%, P = 1.00). Liver failure occurred less often after combined resection and ablation (1.9% vs. 0.6%, P = 0.017). Five-year OS rates were not different (39.3% vs. 33.9%, P = 0.145). ConclusionCombined resection and ablation should be available and considered as an alternative to resection alone in any patient with multiple metastases.

Study Protocol STEREOLAB: Stereotactic Liver Ablation Assisted with Intra-Arterial CT Hepatic Arteriography and Ablation Confirmation Software Assessment.

This study aims to evaluate the technical efficacy and local tumor progression-free survival (LTPFS) of a standardized workflow for thermal ablation of colorectal liver metastases (CRLM) consisting of CT during hepatic arteriography (CTHA)-based imaging analysis, stereotactic thermal ablation, and computer-based software assessment of ablation margins. This investigator initiated, single-center, single-arm prospective trial will enroll up to 50 patients (≤ 5 CRLM, Measuring ≤ 5cm). Procedures will be performed in an angio-CT suite under general anesthesia. The primary objective is to estimate LTPFS with a follow-up of up to 2years and secondary objectives are analysis of the impact of minimal ablative margins on LTPFS, adverse events, contrast media utilization and radiation exposure, overall oncological outcomes, and anesthesia/procedural time. Adverse events (AE) will be recorded by CTCAE (Common Toxicity Criteria for Adverse Events), and Bayesian optimal phase-2 design will be applied for major intraprocedural AE stop boundaries. The institutional CRLM ablation registry will be used as benchmark for comparative analysis with the historical cohort. The STEREOLAB trial will introduce a high-precision and standardized thermal ablation workflow for CRLM consisting of CT during hepatic arteriography imaging, stereotactic guidance, and ablation confirmation. Trial Registration ClinicalTrials.gov identifier: (NCT05361551).

Rates and Patterns of Recurrence After Microwave Ablation of Colorectal Liver Metastases: A Per Lesion Analysis of 416 Tumors in the Era of 2.45GHz Generators.

For some patients with colorectal liver metastases (CRLMs), surgical resection of all visible disease can lead to long-term survival and even cure. When complete resection is not feasible, microwave ablation (MWA) can help achieve hepatic disease control. As modern 2.45-GHz MWA generators gain popularity, the characteristics of tumors most likely to benefit from this method remain unclear. This study aimed to evaluate local recurrence (LR) rates, patterns of recurrence, and factors contributing to treatment failure after 2.45-GHz MWA of CRLM. Patients with CRLM who underwent operative 2.45-GHz MWA between 2011 and 2019 were identified in a prospectively maintained single-institution database. Recurrence outcomes were ascertained for each lesion by imaging review. Factors associated with LR were analyzed. The study enrolled 184 patients bearing 416 ablated tumors. Most of the patients (65.8%) had high clinical risk scores (3-5), and 165 (90%) underwent concurrent liver resection. The median tumor size was 10 mm. After a median follow-up period of 28.8 months, LR was observed in 45 tumors, and the cumulative incidence of LR at 24 months was 10.9% (95% confidence interval [CI], 8.0-14.3%]. In 7%, LR was the first recurrence site, often combined with recurrence elsewhere. The cumulative incidence of LR at 24 months was 6.8% (95% CI 3.8-11.0%) for tumors 10 mm in size or smaller, 12.4% (95% CI 7.8-18.1%) for tumors 11 to 20 mm in size, and 30.2% (95% CI 14.2-48.0%) for tumors larger than 20 mm. In the multivariable analysis, tumors larger than 20 mm with a subcapsular location were significantly associated with increased LR risk. Treatment of CRLM with 2.45-GHz MWA offers excellent local control at 2 years and is most successful for small tumors deep within the parenchyma.

Ablation therapy for patients with colorectal liver metastases with and without extrahepatic metastases: evaluation of long-term outcomes and prognostic factors.

Ablation is a valuable treatment alternative to surgery for colorectal liver metastases. This study reports the long-term clinical outcomes in patients treated with ablation for colorectal liver metastases with or without extrahepatic metastases. Patients with colorectal liver metastases treated with ultrasound-guided ablation at Herlev Hospital, Denmark were included in this retrospective study. This study included 284 patients with 582 metastases. Complete ablation was obtained in 258 patients (91%) evaluated within 6 weeks. During follow-up, 94 patients (33%) developed local recurrence. The median survival for all patients was 31 months, with 1-, 3-, and 5-year survival rates of 82%, 45%, and 21%, respectively. The median survival for patients with extrahepatic metastases (n=49, 17%) was 24 months compared with 33 months for patients without (P=0.142). Propensity score-adjusted Cox regression showed that extrahepatic metastases were associated with increased mortality, with a hazard ratio (HR) of 1.45 (95% confidence interval [CI], 1.02 to 2.05; P=0.039). In multivariate Cox regression analysis for all patients, increased mortality risk was found for a diameter ≥2.6 cm (HR, 1.59; 95% CI, 1.23 to 2.05), >1 metastasis (HR, 1.66; 95% CI, 1.28 to 2.16), and extrahepatic metastases (HR, 1.45; 95% CI, 1.04 to 2.03). Male sex (HR, 0.75; 95% CI, 0.58 to 0.98) and receiving chemotherapy (HR, 0.69; 95% CI, 0.52 to 0.92) were associated with decreased mortality. Ablation for colorectal liver metastases offers acceptable survival rates, including for patients with extrahepatic metastases. In addition, chemotherapy was associated with improved survival for both patients with and without extrahepatic metastases.

Use of Contrast Media During CT-guided Thermal Ablation of Colorectal Liver Metastasis for Procedure Planning is Associated with Improved Immediate Outcomes.

The aim of this study was to analyze the impact of using intra-procedural pre-ablation contrast-enhanced CT prior to percutaneous thermal ablation (pre-ablation CECT) of colorectal liver metastases (CLM) on local outcomes. This retrospective analysis of a prospectively collected liver ablation registry included 144 consecutive patients (median age 57years IQR [49, 65], 60% men) who underwent 173 CT-guided ablation sessions for 250 CLM between October 2015 and March 2020. In addition to oncologic outcomes, technical success was retrospectively evaluated using a biomechanical deformable image registration software for 3D-minimal ablative margin (3D-MAM) quantification. Bayesian regression was used to estimate effects of pre-ablation CECT on residual unablated tumor, 3D-MAM, and local tumor progression-free survival (LTPFS). Pre-ablation CECT was acquired in 71/173 (41%) sessions. Residual unablated tumor was present in one (0.9%) versus nine tumors (6.6%) ablated with versus without using pre-ablation CECT, respectively (p = 0.024). Pre-ablation CECT use decreased the odds of residual disease on first follow-up by 78% (CI95% [5, 86]) and incomplete ablation (3D-MAM ≤ 0mm) by 58% (CI95% [13, 122]). The odds ratio for residual unablated tumor for larger CLM was lower when pre-ablation CECT was used (odds ratio 1.0 with pre-ablation CECT vs. 2.52 without). Pre-ablation CECT use was not associated with improvements on LTPFS. Pre-ablation CECT is associated with improved immediate outcomes by significantly reducing the incidence of residual unablated tumor and by mitigating the risk of incomplete ablation for larger CLM. We recommend performing baseline intra-procedural pre-ablation CECT as a standard imaging protocol. Level 3 (retrospective cohort study).

Meta-analysis of Microwave Ablation vs. Radiofrequency Ablation for Colorectal Liver Metastases

Meta-analysis of Microwave Ablation vs. Radiofrequency Ablation for Colorectal Liver Metastases

Radiofrequency ablation versus microwave ablation for colorectal liver metastases: long-term results of a retrospective cohort surgical experience

Radiofrequency ablation versus microwave ablation for colorectal liver metastases: long-term results of a retrospective cohort surgical experience

Tumor burden and liver specific survival after resection +/- ablation of colorectal liver metastasis

Background: In patients with colorectal liver metastases (CRLM), intraoperative ablation is commonly utilized in combination with surgical resection to extend resectability. Intraoperative ablation can treat select lesions and allow the surgeon to maximize parenchyma preservation and leave the patient with a larger future liver remnant (FLR) during curative intent surgery. The purpose of the study was to compare liver specific disease-free survival (LS-DFS) in patients with multifocal CRLM who underwent curative-intent liver surgery and received either surgical resection (SR) alone versus surgical resection + intraoperative ablation (+IA).

Survival after Combined Liver Resection and Thermal Ablation for Colorectal Liver Metastases: A Nationwide Population-based Propensity Score-matched Study

Survival after Combined Liver Resection and Thermal Ablation for Colorectal Liver Metastases: A Nationwide Population-based Propensity Score-matched Study

Predictive Factors for Local Recurrence after Intraoperative Microwave Ablation for Colorectal Liver Metastases.

This study aimed to clarify local recurrence (LR) predictive factors following intraoperative microwave ablation (MWA) for colorectal liver metastases. The data from 195 patients with 1392 CRLM lesions, who were preoperatively diagnosed by gadolinium-enhanced MRI with diffusion-weighted imaging and dynamic CT and treated with intraoperative MWA (2450 MHz) with or without hepatectomy, from January 2005 to December 2019, were retrospectively reviewed and analyzed using logistic regression. In addition, the margins were measured on contrast-enhanced CT 6 weeks post-ablation. Overall, 1066 lesions were ablated. The LRs occurred in 44 lesions (4.1%) among 39 patients (20.0%). The multivariate analysis per patient showed that tumor size > 20 mm and ablation margin < 5 mm were significant predictors for LR. Furthermore, multivariate analysis per lesion revealed that segments 1, 7, and 8 and tumor size > 15 mm, ablation margin < 5 mm, tumor size > 20 mm, and proximity to the Glisson were significant LR predictors. Finally, the outcome of this study may help determine indications for MWA.

Local tumour control after radiofrequency or microwave ablation for colorectal liver metastases in relation to histopathological growth patterns.

Regrowth after ablation is common, but predictive factors for local control are scarce. This study investigates whether histopathological growth patterns (HGP) can be used as a predictive biomarker for local control after ablation of colorectal liver metastases (CRLM). Patients who received simultaneous resection and ablation as first treatment for CRLM between 2000 and 2019 were considered eligible. HGPs were determined on resected CRLM according to international guidelines and were classified as desmoplastic or non-desmoplastic. As minimal inter-tumoural heterogeneity has been demonstrated, the HGP of resected and ablated CRLM were presumed to be identical. Local tumour progression (LTP) was assessed on postoperative surveillance imaging. Uni- and multivariable competing risk methods were used to compare LTP. In total 221 patients with 443 ablated tumours were analysed. A desmoplastic HGP was found in 60 (27.1%) patients who had a total of 159 (34.7%) ablated lesions. Five-year LTP [95%CI] was significantly higher for ablated CRLM with a presumed non-desmoplastic HGP (37% [30-43] vs 24% [17-32], Gray's-test p=0.014). On multivariable analysis, a non-desmoplastic HGP (adjusted HR [95%CI]; 1.55 [1.03-2.35]) was independently associated with higher LTP rates after ablation. HGP is an independent predictor of local tumour progression following ablation of CRLM.