Periprocedural risk factors for incomplete radiofrequency ablation of liver metastases from colorectal cancer: a single-center retrospective analysis

Radiofrequency ablation: mechanisms and clinical applications

Radiofrequency ablation (RFA), a form of thermal ablation, employs localized heat to induce protein denaturation in tissue cells, resulting in cell death. It has emerged as a viable treatment option for patients who are ineligible for surgery in various diseases, particularly liver cancer and other tumor-related conditions. In addition to directly eliminating tumor cells, RFA also induces alterations in the infiltrating cells within the tumor microenvironment (TME), which can significantly impact treatment outcomes. Moreover, incomplete RFA (iRFA) may lead to tumor recurrence and metastasis. The current challenge is to enhance the efficacy of RFA by elucidating its underlying mechanisms. This review discusses the clinical applications of RFA in treating various diseases and the mechanisms that contribute to the survival and invasion of tumor cells following iRFA, including the roles of heat shock proteins, hypoxia, and autophagy. Additionally, we analyze‌ the changes occurring in infiltrating cells within the TME after iRFA. Finally, we provide a comprehensive summary of clinical trials involving RFA in conjunction with other treatment modalities in the field of cancer therapy, aiming to offer novel insights and references for improving the effectiveness of RFA.

Percutaneous radiofrequency ablation of liver metastases from colorectal cancer: Development of a prognostic score to predict overall survival

PURPOSE

To develop a model for pretreatment prediction of overall survival (OS) after radiofrequency ablation (RFA) for colorectal liver metastasis (CRLM).

METHOD

This retrospective study included 491 patients (median age, 61 years; 348 men) who underwent percutaneous RFA for CRLM between 2000 and 2021. The Kaplan-Meier method was used to estimate OS rates. Independent factors affecting OS were investigated using multivariable Cox regression analysis. Risk scores were assigned to the risk factors and pretreatment prediction models were created using the risk factors.

RESULTS

After RFA, the 5-, 10-, and 20-year OS rates were 44 %, 31 %, and 24 %, respectively, and the median OS was 46 months. Multivariate Cox regression analysis showed that a largest tumor size ≥ 2 cm (P<0.001), positive nodal status of primary tumor (P<0.001), carcinoembryonic antigen level > 30 ng/mL (P=0.049), multiple tumors (P=0.008), and T4 stage of the primary tumor (P=0.029) were independently associated with OS. In patients with a single CRLM, tumor diameter (P<0.001), positive nodal status of primary tumor (P=0.001), disease-free interval <12 months (P=0.045), and subcapsular location (P=0.03) were risk factors affecting OS. According to our prediction models, which included the aforementioned risk factors, OS rates progressively decreased as the risk scores increased, with significantly different OS rates between contiguous groups (P<0.001).

CONCLUSIONS

Our prediction models can be used as a prognostic stratification tool in patients with CRLM, and can help select those candidates who will benefit most from RFA.

Comparison of Effectiveness and Safety of Microwave Ablation of Colorectal Liver Metastases Adjacent versus Nonadjacent to the Diaphragm

PURPOSE

To compare the effectiveness and safety of percutaneous microwave ablation (MWA) for colorectal liver metastasis (CLM) adjacent versus nonadjacent to the diaphragm.

MATERIALS AND METHODS

This was a retrospective analysis of a prospectively created MWA database, from 2 prospective clinical trials for patients with CLM treated in a single tertiary center from 2012 to 2023. CLM adjacent to the diaphragm was defined as a tumor located <1 cm from the diaphragm. Minimal ablation margin (MM) was calculated with 3-dimensional software using postablation contrast-enhanced computed tomography (CT). Adverse events were assessed with Common Terminology Criteria for Adverse Events (CTCAE) v5.0 classification for 6 months.

RESULTS

Two hundred nine CLMs underwent 191 MWA sessions in 143 patients. Mean tumor diameter was 1.52 cm (SD ± 0.53). Eighty-three of 209 (39.7%) CLMs were adjacent to the diaphragm. There was no difference in local tumor progression-free survival (LTPFS) between CLMs adjacent and nonadjacent to the diaphragm (hazard ratio [HR], 0.65; 95% CI, 0.37-1.16; P = .15). MMs of 5-10 mm and >10 mm were documented in 49.3% versus 46.8% (P = .83) and 21.6% versus 12.6% (P = .16) for CLMs adjacent versus nonadjacent to the diaphragm, respectively. Twelve-month LTPFS was similar between groups (HR, 0.65; 95% CI, 0.37-1.16; P = .15) without local tumor progression for MM of >10 mm. There were 3 Grade IV adverse events: 1 diaphragmatic perforation, 1 liver abscess, and 1 biloma. Pneumothorax was associated with location adjacent to the diaphragm (P < .001) and transpulmonary approach (P < .001). Median length of hospital stay was 2 days (interquartile range [IQR], 1-3 days) for patients who needed thoracostomy (n = 20, 9.6%) compared with 1 day (IQR, 1-8 days) for those who did not, without long-term sequelae.

CONCLUSIONS

MWA of CLM adjacent to the diaphragm is effective and safe, without difference in success and 12-month LTPFS. Pneumothorax was associated with location adjacent to the diaphragm and thoracostomy that resulted in longer hospitalization without long-term sequelae.

Using Patient-Specific 3D Modeling and Simulations to Optimize Microwave Ablation Therapy for Liver Cancer

Microwave ablation (MWA) of liver tumors presents challenges like under- and over-ablation, potentially leading to inadequate tumor destruction and damage to healthy tissue. This study aims to develop personalized three-dimensional (3D) models to simulate MWA for liver tumors, incorporating patient-specific characteristics. The primary objective is to validate the predicted ablation zones compared to clinical outcomes, offering insights into MWA before therapy to facilitate accurate treatment planning. Contrast-enhanced CT images from three patients were used to create 3D models. The simulations used coupled electromagnetic wave propagation and bioheat transfer to estimate the temperature distribution, predicting tumor destruction and ablation margins. The findings indicate that prolonged ablation does not significantly improve tumor destruction once an adequate margin is achieved, although it increases tissue damage. There was a substantial overlap between the clinical ablation zones and the predicted ablation zones. For patient 1, the Dice score was 0.73, indicating high accuracy, with a sensitivity of 0.72 and a specificity of 0.76. For patient 2, the Dice score was 0.86, with a sensitivity of 0.79 and a specificity of 0.96. For patient 3, the Dice score was 0.8, with a sensitivity of 0.85 and a specificity of 0.74. Patient-specific 3D models demonstrate potential in accurately predicting ablation zones and optimizing MWA treatment strategies.

Combined ablation and resection (CARe) for resectable colorectal cancer liver Metastases-A propensity score matching study

BACKGROUND

The efficacy of combining ablation and resection (CARe) in treating unresectable colorectal cancer liver metastases (CRLM) was well established. This study aimed to investigate the surgical and oncological outcomes of CARe strategy focusing on initially resectable CRLM.

PATIENTS AND METHODS

A total of 971 patients with resectable CRLM from a retrospective database of 1414 CRLM patients were enrolled, including 120 in the CARe group and 851 in the hepatectomy alone group. Short- and long-term outcomes were compared between groups using propensity score matching analysis.

RESULTS

After propensity score matching, 96 matched pairs of patients from each group were included. General characteristics of primary tumour and liver metastases were not statistically different between the CARe group and hepatectomy alone group. Disease-free survival (p = 0.257), intrahepatic recurrence-free survival (p = 0.329), and overall survival (p = 0.358) were similar between the two groups. Patients in CARe group had significantly reduced rate of major hepatectomy (5.2% vs. 21.9%, p = 0.001), lower incidence of postoperative hepatic insufficiency (0.0% vs. 5.2%, p = 0.023), and shortened postoperative hospital stay (7 d vs. 8 d, p = 0.019). Multivariate analysis showed that surgical approach did not affect oncologic outcome; liver metastasis with diameter >3 cm was an independent prognostic factor for hepatic recurrence-free and disease-free survival, and RAS status and lymph node metastasis at the primary site were independent prognostic factors for overall survival.

CONCLUSION

For patients with resectable CRLM, CARe may be a better treatment strategy than hepatectomy alone, as it could avoid major hepatectomy and get better surgical outcomes, while providing the similar oncologic results.

An update on locoregional percutaneous treatment technologies in colorectal cancer liver metastatic disease

INTRODUCTION

Liver-dominant metastatic colorectal cancer is noted in approximately 20%-35% of the patients. Systemic chemotherapy remains the first-line treatment for mCRC, but the prognosis is poor due to liver failure. Novel minimally invasive technologies have enabled the optimization of locoregional treatment options.

AREAS COVERED

This is a comprehensive review of novel locoregional treatment technologies, both percutaneous ablation and transcatheter arterial treatments, which can be used to decrease hepatic disease progression in patients with mCRC. Trans-arterial radioembolization is the most recently developed locoregional treatment for metastatic liver disease, and robust evidence has been accumulated over the past years.

EXPERT OPINION

Image-guided techniques, endovascular and ablative, have gained wide acceptance for the treatment of liver malignancies, in selected patients with non-resectable disease. The optimization of dosimetry and microsphere technological advancement will certainly upgrade the role of liver radioembolization segmentectomy or lobectomy in the upcoming years, due to its curative intent. Also, ablative interventions provide local curative intent, offering significant and sustained local tumor control. Standardization protocols in terms of predictability and reliability using immediate treatment assessment and ablation zone software could further ameliorate clinical outcomes.

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.

Biopsy and Margins Optimize Outcomes after Thermal Ablation of Colorectal Liver Metastases

Simple Summary

Thermal ablation (TA) is a non-surgical treatment of cancer that has been used with success in the treatment of colorectal liver metastases (CLM). TA consists of burning the cancer and a rim of surrounding tissue (margin) with a special needle placed in the tumor under image guidance. Despite the technological evolution of TA, tumor progression/recurrence rates remain higher than expected. We present a method that combines tissue and imaging tests performed immediately after ablation to determine whether there is complete tumor destruction or remaining live cancer cells that can cause tumor progression/recurrence. This information can provide guidance for additional treatments for patients with evidence of residual cancer, i.e.,: additional TA at the same or subsequent sitting, or additional chemotherapy and short-interval imaging follow-up to detect recurrence. The presented method proposes a clinical practice paradigm change that can improve clinical outcomes in a large population of patients with CLM treated by TA.

Abstract

Background: Thermal ablation is a definitive local treatment for selected colorectal liver metastases (CLM) that can be ablated with adequate margins. A critical limitation has been local tumor progression (LTP). Methods: This prospective, single-group, phase 2 study enrolled patients with CLM < 5 cm in maximum diameter, at a tertiary cancer center between November 2009 and February 2019. Biopsy of the ablation zone center and margin was performed immediately after ablation. Viable tumor in tissue biopsy and ablation margins < 5 mm were assessed as predictors of 12-month LTP. Results: We enrolled 107 patients with 182 CLMs. Mean tumor size was 2.0 (range, 0.6–4.6) cm. Microwave ablation was used in 51% and radiofrequency ablation in 49% of tumors. The 12- and 24-month cumulative incidence of LTP was 22% (95% confidence interval [CI]: 17, 29) and 29% (95% CI: 23, 36), respectively. LTP at 12 months was 7% (95% CI: 3, 14) for the biopsy tumor-negative ablation zone with margins ≥ 5 mm vs. 63% (95% CI: 35, 85) for the biopsy-positive ablation zone with margins < 5 mm (p < 0.001). Conclusions: Biopsy-proven complete tumor ablation with margins of at least 5 mm achieves optimal local tumor control for CLM, regardless of the ablation modality used.

Local Treatments in the Unresectable Patient with Colorectal Cancer Metastasis: A Review from the Point of View of the Medical Oncologist

For patients with isolated liver metastases from colorectal cancer who are not candidates for potentially curative resections, non-surgical local treatments may be useful. Non-surgical local treatments are classified according to how the treatment is administered. Local treatments are applied directly on hepatic parenchyma, such as radiofrequency, microwave hyperthermia and cryotherapy. Locoregional therapies are delivered through the hepatic artery, such as chemoinfusion, chemoembolization or selective internal radiation with Yttrium 90 radioembolization. The purpose of this review is to describe the different interventional therapies that are available for these patients in routine clinical practice, the most important clinical trials that have tried to demonstrate the effectiveness of each therapy and recommendations from principal medical oncologic societies.

Image-Guided Ablation for Colorectal Liver Metastasis: Principles, Current Evidence, and the Path Forward

Image-guided ablation can provide effective local tumor control in selected patients with CLM. A randomized controlled trial suggested that radiofrequency ablation combined with systemic chemotherapy resulted in a survival benefit for patients with unresectable CLM, compared to systemic chemotherapy alone. For small tumors, ablation with adequate margins can be considered as an alternative to resection. The improvement of ablation technologies can allow the treatment of tumors close to major vascular structures or bile ducts, on which the applicability of thermal ablation modalities is challenging. Several factors affect the outcomes of ablation, including but not limited to tumor size, number, location, minimal ablation margin, RAS mutation status, prior hepatectomy, and extrahepatic disease. Further understanding of the impact of tumor biology and advanced imaging guidance on overall patient outcomes might help to tailor its application, and improve outcomes of image-guided ablation.