Selection criteria for radiofrequency ablation for colorectal liver metastases in the era of effective systemic therapy: a clinical score based proposal

Potential for cure and predictors of long-term survival after radiofrequency ablation for colorectal liver metastases: A 20-years single-center experience

BACKGROUND

Additional radiofrequency ablation (RFA) of liver-limited colorectal liver metastases (CRLM) improves overall (OS) and recurrence-free survival (RFS) over systemic therapy alone. We aimed to assess the potential and predictive factors of long-term survival and cure to optimize patient selection for RFA application.

METHODS

Retrospective review of a prospectively maintained single-center database of consecutive patients undergoing RFA for liver-limited CRLM after systemic therapy between 2002 and 2020. Clinicopathologic characteristics and KRAS/BRAF-genotype data (tested routinely since 2010) were correlated to RFS and OS. Cure was defined as ≥10-years RFS (long-term survival as ≥5-years OS) following RFA.

RESULTS

For the entire cohort of 158 patients (median follow-up 13.6 years), co-occurrence of three factors, RECIST-defined response, number of ≤3 CRLM, and ≤3 cm maximum size determined a survival plateau that distinguished cured from non-cured patients (10-years RFS: 15.5% vs 0%, p < 0.0001). Among 59 patients (37.3%) being tested, 4(6.8%) were BRAF-mt, 15(25.4%) KRAS-mt, and 40(67.8%) KRAS/BRAF-wt. OS (median follow-up 8.3 years) was estimated to be higher with KRAS/BRAF-wt compared to a mutant KRAS or BRAF status (5-years OS: 22.8% vs 3.4%, p = 0.0018).

CONCLUSION

This study indicates about 15% chance of cure following RFA of low-volume liver-limited CRLM after downsizing by systemic therapy and a negative effect of KRAS or BRAF mutation on long-term survival after CRLM ablation. These findings may improve clinical decision-making in patients potentially candidate to RFA of CRLM and encourage further investigations on molecular factors determining an oligometastatic state of CRLM curable with focal ablative therapy.

Evidence on percutaneous radiofrequency and microwave ablation for liver metastases over the last decade

Purpose

This review aimed to summarize the treatment outcomes of percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) for metastatic liver tumors based on the findings of published studies over the last decade.

Materials and methods

Literature describing the survival outcomes of ablation therapy for liver metastases was explored using the PubMed database on April 26, 2022, and articles published in 2012 or later were selected. The included studies met the following criteria: (i) English literature, (ii) original clinical studies, and (iii) literature describing overall survival (OS) of thermal ablation for metastatic liver tumors. All case reports and cohort studies with fewer than 20 patients and those that evaluated ablation for palliative purposes were excluded.

Results

RFA was the most commonly used method for ablation, while MWA was used in several recent studies. RFA and MWA for liver metastases from various primary tumors have been reported; however, majority of the studies focused on colorectal cancer. The local control rate by RFA and MWA varied widely among the studies, ranging approximately 50–90%. Five-year survival rates of 20–60% have been reported following ablation for colorectal liver metastases by a number of studies, and several reports of 10-year survival rates were also noted.

Conclusion

Comparative studies of local therapies for colorectal liver metastases demonstrated that RFA provides comparable survival outcomes to surgical metastasectomy and stereotactic body radiation therapy.

A prognostic nomogram for intrahepatic progression-free survival in patients with colorectal liver metastases after ultrasound-guided percutaneous microwave ablation

PURPOSE

The present study identified predictors of intrahepatic progression-free survival (ihPFS) after ultrasound (US)-guided percutaneous microwave ablation (MWA) for colorectal liver metastases (CRLMs) and developed a nomogram to predict ihPFS.

METHODS

From January 2013 to December 2018, a total of 314 patients (224 men and 90 women; mean age, 57.1 ± 11.8 years; range, 23-86 years) with 645 CRLMs (mean diameter, 16.6 ± 6.5 mm; range, 6.0-45.0 mm) treated with US-guided percutaneous MWA were included and analyzed. The average number of CRLMs per patient treated was 2 (range, 1-8). A nomogram to predict ihPFS was developed based on a multivariable Cox model. Validation of the nomogram was performed using the concordance index (C-index), calibration curves, and decision curve analyses.

RESULTS

The 1-, 2-, and 3-year cumulative ihPFS rates were 59.0%, 38.9%, and 30.8%, respectively. Maximal CRLM size, number of CRLMs, ablative margin, primary tumor lymph node status, and chemotherapy were five independent prognostic factors for ihPFS. The C-index of the nomogram was 0.702 (CI: 0.681-0.723). A risk classification system that perfectly classified the patients into three risk groups was constructed. The median ihPFS of patients in the low-, intermediate-, and high-risk groups was 36.3 months (95% CI: 21.4-51.1), 13.4 months (95% CI: 12.1-14.6), and 3.8 months (95% CI: 2.3-5.3), respectively.

CONCLUSION

The nomogram and risk classification system will facilitate the personalized assessment of ihPFS for patients receiving US-guided percutaneous MWA for CRLMs.

Stereotactic body radiation therapy and radiofrequency ablation for the treatment of liver metastases: How and when?

Limited liver metastases represent a clinical challenge. Surgical approach is the most frequently reported treatment option, however, some patients are not eligible for surgical interventions. Relatively recent technologic advances have permitted the safe use of ablative techniques employed in the cure of hepatic metastases. Among these, radiofrequency ablation (RFA) and stereotactic body radiotherapy (SBRT) have emerged as valid treatments in a significant proportion of patients with intrahepatic oligometastatic disease. This review offers an up-to-date of current available literature on this issue focusing on the use and outcomes of RFA and SBRT, according to the PICO (Population, Intervention, Comparison and Outcomes) criteria.

Computer modeling and in vitro experimental study of water-cooled microwave ablation array

INTRODUCTION

Microwaves (MWs) quickly deliver relatively high temperatures into tumors and cover a large ablation zone. We present a research protocol for using water-cooled double-needle MW ablation arrays for tumor ablation here.

MATERIAL AND METHODS

Our research program includes computer modeling, tissue-mimicking phantom experiments, and in vitro swine liver experiments. The computer modeling is based on the finite element method (FEM) to evaluate ablation temperature distributions. In tissue-mimicking phantom and in vitro swine liver ablation experiments, the performances of the new device and the single-needle MW device currently used in clinical practice are compared.

RESULTS

FEM shows that the maximum transverse ablation diameter (MTAD) is 4.2 cm at 100 W output and 300 s (assessed at the 50 °C isotherm). In the tissue-mimicking phantom, the MTDA is 2.6 cm at 50 W and 300 s in single-needle MW ablation, and 4 cm in double needle MW ablation array. In in vitro swine liver experiments, the MTAD is 2.820 ± 0.127 cm at 100 W and 300 s in single-needle MW ablation, and 3.847 ± 0.103 cm in MW ablation array.

CONCLUSION

A new type of water-cooled MW ablation array is designed and tested, and has potential advantages over currently used devices.

Can tumor coverage evaluated 24 h post-radiofrequency ablation predict local tumor progression of liver metastases?

Purpose

To assess the predictive value for local tumor progression (LTP) of geometrical tumor coverage using the contrast-enhanced (ce-)CT images acquired before and within 24 h after radiofrequency (RF) ablation.

Methods

Twenty patients (6 male and 14 female, median age 62 years) with 45 focal hypovascular liver metastases (16 colorectal carcinoma, 3 melanoma and 1 breast carcinoma) underwent RF ablation under CT-guidance and received a ce-PET/CT scan within 24 h post-procedure. Pre- and post-ablation ce-CT-images were aligned using an interactive procedure and used to verify the tumor coverage of the RF ablation. Results were correlated to LTP as recorded during follow-up performed every 2–3 months after the intervention (mean follow-up of 110 weeks) and compared to standard reading performed by three readers of the ce-CT images.

Results

Eleven tumors (25%) showed LTP during the follow-up period. One lesion, which did not show LTP, was excluded from analysis due to the poor quality of the alignment. For the remaining, 29 (66%) tumors were completely covered by the ablation zone, 9 (20%) were not, and for 6 (14%) tumors the edges coincided with the edge of the ablation zone. The sensitivity, specificity, PPV and NPV for LTP of having incomplete tumor coverage or no apparent ablative margin versus standard reading of ce-CT were 100, 88, 73 and 100% versus 42, 88, 58 and 82%, respectively.

Conclusions

Verifying the tumor coverage of liver metastases by an ablation zone through alignment of pre- and early post-ablation ce-CT images has a high predictive value for LTP.

Personalizing prognosis in colorectal cancer: A systematic review of the quality and nature of clinical prognostic tools for survival outcomes

Integrating diverse types of prognostic information into accurate, individualized estimates of outcome in colorectal cancer is challenging. Significant heterogeneity in colorectal cancer prognostication tool quality exists. Methodology is incompletely or inadequately reported. Evaluations of the internal or external validity of the prognostic model are rarely performed. Prognostication tools are important devices for patient management, but tool reliability is compromised by poor quality. Guidance for future development of prognostication tools in colorectal cancer is needed.

Does primary tumor location impact the prognosis of colorectal liver metastases patients after microwave ablation? - Lessons from 10 years' experience

Thermal ablation has been considered as an alternative for local curative intent in patients with unresectable colorectal liver metastases. The influence of primary tumor location on the prognosis of colorectal liver metastases patients who have undergone microwave ablation has yet to be determined. We reviewed 295 patients who underwent microwave ablation for colorectal liver metastases at our institution between March 2006 and March 2016. Univariate and multivariate analyses were performed to identify predictors of overall and progression-free survival. Technical success was achieved in 96.6% of patients (n = 289), with a post-procedural complication rate of 2.0% (n = 6). After a median follow-up of 24 (range, 2–86) months, comparable overall survival rates (p = 0.583) were observed in patients with different primary tumor locations. Patients with colorectal liver metastases originating from left-sided primary colon cancer exhibited a better progression-free survival than patients whose colorectal liver metastases had originated from right-sided primary colon cancer (hazard ratio: 0.67, 95.0% confidence interval: 0.48–0.94; p = 0.012), which was further confirmed in a multivariate analysis after adjustment for other potential prognostic factors. Stratification based on primary tumor location should be taken into consideration in the assessment of disease progression in patients who intend to undergo microwave ablation for colorectal liver metastases.

Surgical resection for hepatic metastasis from gastric cancer: a multi- institution study

Background

The beneficial effect of surgical resection for hepatic metastasis from gastric cancer (HMGC) remains elusive. This study was conducted to analyze surgical outcomes of HMGC and determine the prognostic factors associated with survival.

Results

The in-hospital mortality rate was zero, and the overall morbidity rate was 56%. The overall 1-, 3-, and 5-year survival rate after surgery was 87.5%, 47.6%, and 21.7%, respectively, with a median survival time of 34.0 months. Multiple liver metastases (hazard ratio [HR] =1.998; 95% confidence interval [CI] = 1.248-3.198; P = 0.004) and ≥ T3 stage of the primary gastric cancer (HR = 2.065; 95% CI = 1.201–3.549; P = 0.009) were independent prognostic determinants in the multivariate analysis.

Materials and Methods

Data on surgical resection of 96 patients with HMGC at six institutions in China were analysed retrospectively. Prognostic factors were assessed by multiple stepwise regression analysis using the Cox model.

Conclusions

Surgical resection for HMGC is feasible and beneficial to long-term survival in selected patients.

Microwave ablation is effective against liver metastases from gastric adenocarcinoma

PURPOSE

The resection rate for liver metastases from gastric cancer is only 1.4-21.1%. This study aimed to evaluate the safety and therapeutic efficacy of microwave ablation (MWA) for liver metastases from gastric adenocarcinoma (LMGC).

MATERIALS AND METHODS

A database of 108 gastric adenocarcinoma patients with liver metastases who underwent MWA (n = 32) or systemic chemotherapy (n = 76) for LMGC between 2008 and 2016 was reviewed. Overall survival curves were assessed and compared based on different therapies.

RESULTS

All the patients were followed up for a median of 15 months (range, 2-68 months). The median cumulative survival times of patients after MWA and systemic chemotherapy were 25 (95% confidence interval (CI) 16.5-33.5) months and 12 (95% CI 7.7-16.3) months, respectively (HR 1.751, 95% CI 1.077-2.845; p = .015). The 1-, 3-, and 5- year survival rates were 80.9%, 31.2%, and 16.7% (MWA group); and 50.0%, 18.8%, and 5.4% (chemotherapy group), respectively. In the MWA group, side effects were reported in eight patients who developed abdominal pain, transient fever, or nausea. Dominant size, number of liver metastases, therapeutic modalities, and presence of extrahepatic metastases showed significant prognostic value in univariate analyses; while the latter three were identified as independent prognostic factors in multivariate regression analysis.

CONCLUSIONS

MWA is a safe and useful alternative for liver metastases from gastric adenocarcinoma in selected patients.

Impact of Systemic Therapy and Recurrence Pattern on Survival Outcome after Radiofrequency Ablation for Colorectal Liver Metastases

Background: Most patients undergoing radiofrequency ablation (RFA) of colorectal liver metastasases (CLM) develop disease recurrence, but little is known about the effect of recurrence patterns and/or systemic therapy on outcome. In this study, we examined the recurrence patterns and survival after systemic therapy plus RFA in patients with unresectable CLM without extrahepatic disease. The aims were to analyze the effect of recurrence patterns on survival and to assess the relative benefit contributed by systemic therapy and local ablation to disease control and patient outcome. Methods: From January 2002 to December 2012, 113 patients underwent RFA of liver-limited CLM after systemic therapy. Univariate and multivariate analyses for associations between clinical and/or treatment-related variables, recurrence-free survival (RFS), recurrence patterns, and overall survival (OS) were carried out. Results: Of 113 patients, 105 (92.8%) had disease recurrence (median RFS: 6.1 months). Lower post-recurrence OS was observed after early (≤6 months) than after late recurrence (8.5 versus 24.0 months, p < 0.001). Recurrence sites were RFA-sites only (4.8%), liver-only (57.1%), lung-only (10.5%), or multiple (27.6%); the corresponding post-recurrence OS was 21, 19, 39, and 7 months (p < 0.001), respectively. Response to pre-RFA systemic therapy was the strongest predictor for OS (hazard ratio [HR] 5.28), RFS (HR 3.30), early (odds ratio [OR] 6.34) and multiple-site recurrence (OR 3.83) (p < 0.01), respectively; only responders achieved 5-year OS and RFS (29% and 12% versus 0% and 0% for non-responders, p < 0.001, respectively). Conclusions: Survival after RFA for liver-limited CLM is strongly linked to the timing and pattern of non-local disease recurrence. Local ablation efficacy is necessary but not sufficient to obtain long-term disease control. Effective pre-RFA systemic therapy does favourably affect the incidence, timing and patterns of recurrence and long-term survival and appears essential for the tailoring of RFA application to maximize patient benefit.

Liver resection and ablation for metastatic melanoma: A single center experience

BACKGROUND

The median survival for patients with stage IV metastatic melanoma is usually limited to approximately 1 year. In the case of liver metastasis, resection and ablation can achieve long-term survival. This study aimed to describe the outcomes after liver resection or ablation for metastatic melanoma to the liver and identify preoperative prognostic factors.

METHODS

Forty eight patients who underwent liver resection (n = 32) or percutaneous ablation (n = 16) were identified from the 1,523 patients with melanoma liver metastases evaluated between January1993 and January 2013.

RESULTS

Median OS was 25.9 months. Median OS was not different after ablation (18 months) and resection (26 months; P > 0.2). Patients in the ablation group more often presented with extrahepatic disease (EHD) (P = 0.008) and received more frequently systemic therapy before ablation (P = 0.005). Patients without EHD tended to have longer OS (26.5 vs. 12 months; P = 0.076) and PFS (13 vs. 5 months; P = 0.11) in the whole cohort. EHD was significantly associated with a worse OS in the resection group (P = 0.034).

CONCLUSION

Liver resection is associated to prolonged survival over 24 months and should be considered only in selected patients with metastatic disease confined to the liver. In patients not candidate for surgery, tumor ablation can be considered.