Imaging in disappearing colorectal liver metastases and their accuracy: a systematic review

Preoperative imaging of colorectal liver metastases: what the radiologist and the multidisciplinary team need to know

The management of patients with colorectal liver metastases (CRLM) has transformed over the past 2 decades. Advances in surgical techniques, systemic therapies, and local treatments have resulted in a paradigm shift. Disease that would once have been considered terminal is now frequently treated aggressively with both a disease-free and overall survival benefit. In line with the expanding range of treatment options, there has been an increase in the volume and complexity of imaging required in the management of these patients to ensure optimal patient selection and outcome. The radiologist plays a pivotal role in interpreting these studies, conveying the relevant information and informing the discussion at multidisciplinary team meetings. The purpose of this review is to provide an update for radiologists on the current surgical management of patients with CRLM highlighting specific imaging information that is required by the multidisciplinary team when assessing resectability and/or the need for additional liver-directed therapies.

Transplantation for colorectal liver metastasis

PURPOSE OF REVIEW

Liver transplantation has emerged as a possible treatment for selected patients with nonresectable colorectal liver metastasis, but controversy still exists regarding optimal selection criteria and acceptable outcomes.

RECENT FINDINGS

Univariate analysis in the largest cohorts confirms that metachronous disease, Oslo score = 0-1, metabolic tumor volume (MTV) less than 70 cm 3 , and tumor burden score less than 9 are positive predictive factors for good overall survival outcomes. Some recent trials might suggest that technical resectability is not a valid exclusion criterion for patients with high tumor load and favorable prognostic scores in the transplant evaluation. Recent developments in circulation DNA technology and liquid biopsy may play a future role in the selection and monitoring of patients.

SUMMARY

Evaluation for transplant needs multidisciplinary involvement and should not be delayed until the failure of conventional oncological therapy. Larger data sets are needed to refine the selection criteria for liver transplantation in colorectal liver metastasis (CRLM).

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.

Assessment of the response to systemic treatment of colorectal liver metastases on cross-sectional imaging - a systematic review

Colorectal cancer (CRC) is one of the most common malignancies in the world. Nowadays many treatments are available to help control CRC, including surgery, radiation therapy, interventional radiology, and drug treatments. A multidisciplinary approach and the role of radiologists is needed to assist the surgeon in the management thanks to emerging technology and strategies. The Response Evaluation Criteria in Solid Tumours (RECIST) has been created to objectify and standardize cancer response assessment. Thus, in this article specific presumptions and practical aspects of evaluating responses according to the RECIST 1.1 are discussed. Furthermore, examples of possible response to systemic treatment of colorectal liver metastases (CRLM), including tumour necrosis, apparent diffusion coefficient (ADC) values, tumour calcification, tumour fibrosis and intratumoural fat deposition observed on cross-sectional imaging, are described. Disappearing liver metastases (DLM) presents a therapeutic dilemma. The optimal management of DLM remains controversial due to the uncertainty of residual microscopic disease and effective long-term outcomes. The article provides an overview of the CRLM phenomenon and current possible assessment methods of the response to systemic treatment.

Comparison of the therapeutic efficacy between systemic chemotherapy with and without radiofrequency ablation for colorectal cancer liver metastases: A propensity score matching study

OBJECTIVE

To compare therapeutic efficacy between systemic chemotherapy (SC) alone and preoperative SC followed by radiofrequency ablation (SC+RFA) in patients with colorectal cancer liver metastases (CRLM).

METHODS

This study identified a cohort of patients with CRLM after treatment between 2010 and 2016. Patients who received SC+RFA were compared with SC patients by propensity score matching. Overall survival (OS) and intrahepatic progression-free survival (PFS) were compared using stratified log-rank test. The outcomes after SC and SC+RFA were also assessed in patient subgroups.

RESULTS

This study identified 338 patients with CRLM who had underwent SC and had different response to chemotherapy, including non-progressive disease (non-PD) or progressive disease (PD). Of this cohort, 64 patients in SC+RFA group were matched by propensity score to 64 patients who received SC alone. Compared with SC cohort, the SC+RFA cohort yielded better OS (HR, 0.403; 95% CI, 0.271-0.601) and PFS (HR, 0.190; 95% CI, 0.113-0.320). The estimated OS rates at 1, 3 and 5 years were 93.8%, 51.6% and 15.6% for SC+RFA group and 81.3%, 26.6% and 10.9% for SC group (p＜0.001). The cumulative PFS rates at 1, 3, and 5 years were 43.8 %, 14.1% and 3.1% for the SC+RFA group and 1.6%, 0 and 0% for SC group (p＜0.0001). In subgroup analysis, compared with patients with PD response, patients with non-PD response could gain better PFS (HR, 0.207; 95% CI, 0.121-0.354) and OS (HR, 0.390; 95% CI, 0.246-0.617).

CONCLUSIONS

RFA was associated with improved OS and intrahepatic PFS in CRLM patients with preoperative SC,especially in non-PD response subgroup after SC.

ADVANCES IN KNOWLEDGE

The addition of RFA was advocated for CRLM patients with preoperative SC. This study will provide important reference and evidence to better perform the management of unresectable CRLM.

Cost-effectiveness analysis of MRI, CE-CT and 18F-FDG PET/CT for detecting colorectal liver metastases eligible for hepatic resection

OBJECTIVES

Colorectal cancer (CRC) is a serious challenge for the health system. In 2022 CRC represented 8% of cancer diagnoses in the United States. 30% of patients already show metastases at the initial tumor staging. The majority of these metastases are sited in the liver. According to their extension and the status of the tumor colorectal liver metastases can be treated in several ways, with hepatic resection being the gold-standard. Contrast-enhanced computed tomography (CE-CT), positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) can be used for evaluation of resectability of these liver metastases. The aim of this study is to assess the most economic imaging modality for detecting liver metastases eligible for hepatic resection by analyzing their cost-effectiveness.

MATERIALS AND METHODS

In our study, a Markov state transition model was built to calculate the quality-adjusted life years (QALYs) and overall costs for each diagnostic strategy in accord with the stated input values obtained from scientific research. Further, probabilistic sensitivity analyses by means of Monte Carlo simulations were performed to consider possible model uncertainties. For evaluation of the cost-effectiveness on an economic threshold, the Willingness-to-pay (WTP) was set at $ 100,000. The applied values and the calculated results are based on the U.S. healthcare system.

RESULTS

CE-CT led to overall costs of $ 42,874.02 and 8.47 QALYs, whereas MRI led to $ 40,863.65 and 8.50 QALYs. PET/CT resulted in overall costs of $ 43,216.74 and 8.48 QALYs. Therefore, MRI was determined to be the dominant strategy in the model. According to the performed sensitivity analyses, MRI remained cost-effective over a wide range of WTPs.

CONCLUSION

In conclusion, according to our analysis, MRI is the dominant strategy for detecting hepatic metastases eligible for hepatic resection in colorectal cancer.

Economic evaluation of 18F-FDG PET/CT, MRI and CE-CT in selection of colorectal liver metastases eligible for ablation – A cost-effectiveness analysis

OBJECTIVES

Colorectal cancers (CRC) are among the world's most prevailing cancer entities. In a third of all cases, the patients have already developed distant metastases - mainly in the liver - at the time of detection. Colorectal liver metastases (CRLM) can be treated by surgical resection or, as is possible in most cases, by percutaneous ablation. For selecting the liver metastases eligible for radiofrequency ablation (RFA) or microwave ablation (MWA), the common imaging modalities are magnetic resonance imaging (MRI), positron emission tomography/computed tomography (PET/CT), and contrast-enhanced computed tomography (CE-CT). This study aims to evaluate those imaging modalities for selecting liver lesions eligible for ablation according to their long-term cost-effectiveness.

MATERIALS AND METHODS

A Markov model was applied, calculating quality-adjusted life years (QALYs) and accumulative costs for every diagnostic strategy, according to predefined input parameters obtained from published research. Further, sensitivity analyses were executed to prove the certainty of the calculations by running Monte-Carlo simulations with 30,000 reiterations. The Willingness-to-pay (WTP) is at $ 100,000. All calculations are based on the U.S. healthcare system.

RESULTS

CE-CT caused cumulative costs of $ 31,940.98 and 8,99 QALYs, whereas MRI caused $ 32,070.83 and 9,01 QALYs. PET/CT caused cumulative costs of $ 33,013.21 and 8,99 QALYs.

CONCLUSION

In conclusion, according to our analysis, MRI is the most cost-effective strategy for detecting liver metastases eligible for ablation and therefore should be seen as the gold standard.

The dilemma of the disappearing colorectal liver metastases: defining international trends in management

OBJECTIVE

This survey sought to appraise the degree of consistency in the management of disappeared colorectal liver metastases (dCRLM) among liver surgeons in different countries.

BACKGROUND

Colorectal liver metastases (CRLM) account for half of the deaths secondary to colorectal cancer. Due to the high utilization of chemotherapy before surgery, some or all CRLM can disappear (dCRLM) but management of dCRLMs remains unclear.

METHODS

Seven simulated scenarios of dCRLM were presented to experienced liver surgeons using an online platform. Treatment decisions were submitted and analysed using the multi-rater kappa method. The effect of the experience, complexity of scenarios, and location and number of dCRLM on treatment decision were analysed.

RESULTS

Sixty-seven liver surgeons from 25 countries completed the survey. There was no agreement about the therapeutic strategies of dCRLM in all scenarios (kappa 0.12, IQR 0.20-0.32). In scenarios with lower difficulty scores, surgeons tended to offer surgical resection for dCRLM alongside the visible CRLM (vCRLM), however, with poor agreement (kappa 0.32, IQR 0.19-0.51). No agreement was seen for clinical scenario in which all CRLM lesions disappeared (kappa 0.20).

CONCLUSION

There are clear inconsistencies in the management decisions of dCRLM. Better evidence is required to define optimal management strategies.

Complete resolution of rectal cancer with liver metastases after palliative chemoradiotherapy and unplanned surgical resection-a case report

Metastatic colorectal cancer has poor prognosis for many patients at time of diagnosis with <20% 5-year survival rate. Recent advancements in palliative chemotherapy have improved patient outcomes as median survival has increased almost 2-fold. We report a 44-year-old gentleman who initially underwent palliative chemoradiotherapy and subsequently a Hartmann's procedure for ypT3N1M1 upper rectal adenocarcinoma with multiple liver metastases. Fortuitously, he made a remarkable recovery with complete radiological resolution of liver metastasis post-operatively. The patient has remained in remission for the past 10 years.

The Role of Biomarkers in the Management of Colorectal Liver Metastases

Simple Summary

Colorectal cancer remains one of the most significant sources of cancer-related morbidity and mortality worldwide. The liver is the most common site of metastatic spread. Multiple modalities exist to manage and potentially cure patients with metastatic colorectal cancer. However, reliable biomarkers to assist with clinical decision-making are limited. Recent advances in genomic sequencing technology have greatly expanded our knowledge of colorectal cancer carcinogenesis and significantly reduced the cost and timing of the investigation. In this article, we discuss the current utility of biomarkers in the management of colorectal cancer liver metastases.

Abstract

Surgical management combined with improved systemic therapies have extended 5-year overall survival beyond 50% among patients with colorectal liver metastases (CRLM). Furthermore, a multitude of liver-directed therapies has improved local disease control for patients with unresectable CRLM. Unfortunately, a significant portion of patients treated with curative-intent hepatectomy develops disease recurrence. Traditional markers fail to risk-stratify and prognosticate patients with CRLM appropriately. Over the last few decades, advances in molecular sequencing technology have greatly expanded our knowledge of the pathophysiology and tumor microenvironment characteristics of CRLM. These investigations have revealed biomarkers with the potential to better inform management decisions in patients with CRLM. Actionable biomarkers such as RAS and BRAF mutations, microsatellite instability/mismatch repair status, and tumor mutational burden have been incorporated into national and societal guidelines. Other biomarkers, including circulating tumor DNA and radiomic features, are under active investigation to evaluate their clinical utility. Given the plethora of therapeutic modalities and lack of evidence on timing and sequence, reliable biomarkers are needed to assist clinicians with the development of patient-tailored management plans. In this review, we discuss the current evidence regarding biomarkers for patients with CRLM.

Impact of baseline gadoxetic acid-enhanced liver magnetic resonance and diffusion-weighted imaging in resectable colorectal liver metastases: A prospective, monocentric study

BACKGROUND

Liver magnetic resonance imaging (MRI) utilizing hepatocyte-specific contrast agent and diffusion-weighted imaging (DWI) is currently used to properly stage colorectal liver metastases (CRLM) in patients candidate to liver surgery. However, the added value of liver MRI in choosing the treatment strategy in resectable CRLM over computed tomography (CT)-scan is not clear.

PATIENTS AND METHODS

This is a prospective monocentric collection of consecutive cases of patients with CRLM conceived with the aim to assess the added value of liver MRI in changing the initial treatment strategy planned according to CT-scan. Potential changes in the initially planned strategy were defined as: - from upfront surgery to perioperative chemotherapy (fluoropyrimidine and oxaliplatin) - from upfront surgery to first-line systemic therapy (doublet or triplet plus a biological agent) - from perioperative chemotherapy to first-line systemic therapy. Hypothesising that MRI may induce a change in the choice of the treatment strategy in the 20% of cases (alternative hypothesis), against a null hypothesis of 5%, with one-tailed alpha and beta errors of 0.05 and 0.20 respectively, 27 patients were needed. The added value of liver MRI would have been considered clinically meaningful if at least 4 changes in the treatment strategy were observed.

RESULTS

Among 27 enrolled patients, upfront surgery and perioperative chemotherapy strategies were chosen in 17 (63%) and 10 (37%) cases, respectively, based on CT-scan. After liver MRI, additional liver lesions were found in 8 patients (30%) and the initial strategy was changed in 7 patients (26%) (4 initially deemed candidate to upfront surgery and 3 initially sent to perioperative chemotherapy) that were treated with first-line systemic therapy.

CONCLUSIONS

Our results support the indication of the current guidelines on the routine use of liver MRI in the initial workup of patients with resectable CRLM with an MRI-driven changes of initial treatment plan in a relevant percentage of cases.

Role of stereotactic body radiotherapy in multidisciplinary management of liver metastases in patients with colorectal cancer

In the treatment of colorectal cancer patients with distant metastases, the development of new anticancer agents has considerably prolonged progression-free survival. Such survival benefits attributed to chemotherapy have increased the relative significance of local therapy in patients with limited metastases. The liver is recognized as the most common site of metastasis of colorectal cancer because of the intestinal mesenteric drainage to the portal veins. Hepatic resection of isolated liver metastases of colorectal cancer is the only option for a potential cure. However, hepatic metastases are resectable in only approximately 20% of the patients. For remaining patients with high-risk resectable liver metastases or those who are unfit for surgery, less invasive, local therapies including radiation therapy (stereotactic body radiation therapy, SBRT) may have a potential role in treatment. Although the local control rate of SBRT for colorectal liver metastases has room for improvement, its less-invasive nature and broad indications deserve consideration. Future research should include SBRT dose escalation or the selection of patients who benefit from local ablative therapies. SBRT may offer an alternative, non-invasive approach for the treatment of colorectal liver metastases in a multidisciplinary treatment strategy.

A radiological footprint equivalent to liquefactive necrosis observed in the course of disappearing liver metastases in rectal cancer: A case report and review of the literature

A 72-year-old female diagnosed with rectal cancer treated with a surgical procedure was reported. As 3 liver metastases (LMs) appeared in multidetector CT, adjuvant chemotherapy using Bevacizumab combined with modified FOLFOX-6 was completed. LMs were changed to cystic lesions during the follow-up period, consistent with liquefactive necrosis. These cystic lesions that appeared in the course of disappearing LMs (DLMs) were identified by CT as homogeneous low signal intensity in hepatocyte specific Gd-enhanced MRI. This might be pathognomonic radiological footprint equivalent to liquefactive necrosis observed in the process of DLM and must be carefully followed in the course of radiological complete response. The radiological changing findings of LMs to cystic changes, high sensitivity of detecting DLM, and limitations of Gd-MRI might be meaningful to clinicians.

[Multimodal therapy for liver metastases of colorectal carcinoma in curative intention]

Depending on the patient's constitution, the biological conditions of the primary tumor, the metastases and the liver function and perfusion, a variety of therapeutic options are available. The basis of metastatic surgery of the liver is partial liver resection. Multimodal therapies with local and systemic approaches are used in functionally or oncologically borderline situations. They are intended to improve long-term success and allow curative treatment in more patients. In recent years, for isolated lesions that cannot be removed by partial liver resection, an R0 situation is achieved in selected patients by liver transplantation with good long-term success. The large number of treatment options and the increasing individualization of therapy require treatment planning in the interdisciplinary tumor board. Also, in view of promising studies, for example, in the field of liver transplantation as well as regional therapy methods, the range of treatment options has not yet been exhausted.

The management of colorectal liver metastases amenable of surgical resection: How to shape treatment strategies according to clinical, radiological, pathological and molecular features

Metastatic colorectal cancer (mCRC) patients have poor chances of long term survival, being < 15% of them still alive after 5 years from diagnosis. Nonetheless, patients with colorectal liver metastases (CRLM) may be eligible for metastases resection thus being able to achieve long-term disease remission and survival. The likelihood for patients with CRLM of being or becoming eligible for liver metastasectomy is increasing, thanks to the evolution of surgical techniques, the availability of active systemic treatments and the widespread diffusion of experienced multidisciplinary boards to manage these patients. However, disease relapse after liver surgery is common and occurs in two-thirds of resected patients. Therefore, adequate radiological staging and risk stratification is crucial for the optimal selection of patients candidate to surgery in order to maximize the benefit-risk ratio of liver metastasectomy and to individualize the treatment strategy. Based on the multidimensional assessment, three possible approaches are available: upfront liver surgery followed by adjuvant chemotherapy, perioperative chemotherapy preceding and following liver surgery, and an upfront systemic treatment including chemotherapy plus a targeted agent, both chosen according to patients' and tumours' characteristics, then followed by liver surgery if indicated. In this review, we describe the most important factors impacting the therapeutic choices in patients with resectable and potentially resectable CRLM, and we discuss the most promising factors that may reshape the future decision-making process of these patients.

Imaging evaluation of the liver in oncology patients: A comparison of techniques

The liver is commonly affected by metastatic disease. Therefore, it is essential to detect and characterize liver metastases, assuming that patient management and prognosis rely on it. The imaging techniques that allow non-invasive assessment of liver metastases include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET)/CT, and PET/MRI. In this paper, we review the imaging findings of liver metastases, focusing on each imaging modality’s advantages and potential limitations. We also assess the importance of different imaging modalities for the management, follow-up, and therapy response of liver metastases. To date, both CT and MRI are the most appropriate imaging methods for initial lesion detection, follow-up, and assessment of treatment response. Multiparametric MRI is frequently used as a problem-solving technique for liver lesions and has evolved substantially over the past decade, including hardware and software developments and specific intravenous contrast agents. Several studies have shown that MRI performs better in small-sized metastases and moderate to severe liver steatosis cases. Although state-of-the-art MRI shows a greater sensitivity for detecting and characterizing liver metastases, CT remains the chosen method. We also present the controversial subject of the "economic implication" to use CT over MRI.

Postoperative circulating tumour DNA is associated with pathologic response and recurrence-free survival after resection of colorectal cancer liver metastases

Background

Recurrence rates after resection of colorectal cancer liver metastases (CRLM) are high and correlate with worse survival. Postoperative circulating tumour DNA (ctDNA) is a promising prognostic biomarker. Focusing on patients with resected CRLM, this study aimed to evaluate the association between the detection of postoperative ctDNA, pathologic response and recurrence-free survival (RFS).

Methods

Twenty-three patients were selected from an ongoing phase-3 trial who underwent resection of RAS-mutant CRLM after induction systemic treatment. CtDNA analysis was performed by droplet digital PCR using blood samples collected at baseline, before and after resection. Pathologic response of CRLM was determined via the Tumour Regression Grading system.

Findings

With a median follow-up of 19.6 months, the median RFS for patients with detectable (N = 6, [26%]) and undetectable (N = 17, [74%]) postoperative ctDNA was 4.8 versus 12.1 months, respectively. Among 21 patients with available tumour tissue, pathologic response in patients with detectable compared to undetectable postoperative ctDNA was found in one of six (17%) and 15 of 15 (100%) patients, respectively (p < 0.001). In univariable Cox regression analyses both postoperative detectable ctDNA (HR = 3.3, 95%CI = 1.1–9.6, p = 0.03) and pathologic non-response (HR = 4.6, 95%CI = 1.4–15, p = 0.01) were associated with poorer RFS and were strongly correlated (r = 0.88, p < 0.001). After adjusting for clinical characteristics in pairwise multivariable analyses, postoperative ctDNA status remained associated with RFS.

Interpretation

The detection of postoperative ctDNA after secondary resection of CRLM is a promising prognostic factor for RFS and appeared to be highly correlated with pathologic response.