Histopathologic Changes After Yttrium-90 Radioembolization of Colorectal Liver Metastases: A Pilot Feasibility Study

PURPOSE

To evaluate the histopathologic changes and potential correlations of tissue radiation absorbed dose (TAD) after 90Y transarterial radioembolization (TARE) for colorectal liver metastases (CLM).

MATERIALS AND METHODS

This prospective pilot study assessed 12 patients with 13 (CLM) through PET/CT--guided biopsies before, immediately (T0) and 3 weeks (T3) after TARE. Subsequent sampling from the same location was enabled by fiducial placement. Biopsy samples were evaluated with hematoxylin-eosin (H&E), TUNEL, Ki67, OxPhos, caspase-3 (CC3), and pH2AX antibodies. Proliferation changes (Ki67) and double-strand DNA breaks (DSBs) were evaluated quantitatively. TAD was calculated on post-TARE PET/CT scan of the biopsy needle location at T0 and T3.

RESULTS

Median TAD at 3 weeks post-TARE was 162 (IQ R:92-211) Gy. DSBs decreased significantly from T0 (median 77%; IQR:75-100%) to T3 (median 14%; IQR:0-54%, p=0.03). A decrease in Ki67 was also documented (median: 73%, IQR:70-80% at T0 vs 41%, IQR:0-66% at T3, p=0.05). There was a strong negative correlation between TAD and DSBs at T0 (r(9)=0.68) and a strong negative correlation at T3 (r(10)=-0.855), (p=0.042 and p=0.002, respectively). There was a strong negative correlation between TAD and Ki67 at both T0 (r(9)=-0.733; p=0.025) and T3 (r(10)=-0.681; p=0.03). Tumors that exhibited caspase-3 activation (8/13, 62%) at either T0 or T3 time point were more likely to develop progression (7/8, 88% vs 1/5, 20%, p=0.015).

CONCLUSION

Post-TARE biopsy can be used to assess TAD and histopathologic changes. Significant decreases in double-strand DNA breaks and proliferation index were noted post TARE. Post-TARE CC3 activation deserves further exploration.

Comparison of periprocedural and procedure room times between moderate sedation and monitored anesthesia care in interventional radiology

Objectives

In recent years, there has been increased utilization of monitored anesthesia care (MAC) in interventional radiology (IR) departments. The purpose of this study was to compare pre-procedure bed, procedure room, and post-procedure bed times for IR procedures performed with either nurse-administered moderate sedation (MOSED) or MAC.

Material and Methods

An institutional review board-approved single institution retrospective review of IR procedures between January 2010 and September 2022 was performed. Procedures performed with general anesthesia or local anesthetic only, missing time stamps, or where <50 cases were performed for both MAC and MOSED were excluded from the study. Pre-procedure bed, procedure room, post-procedure bed, and total IR encounter times were compared between MAC and MOSED using the t-test. The effect size was estimated using Cohen's d statistic.

Results

97,480 cases spanning 69 procedure codes were examined. Mean time in pre-procedure bed was 27 min longer for MAC procedures (69 vs. 42 min, P < 0.001, d = 0.95). Mean procedure room time was 11 min shorter for MAC (60 vs. 71 min, P < 0.001, d = 0.48), and mean time in post-procedure bed was 10 min longer for MAC (102 vs. 92 min, P < 0.001, d = 0.22). Total IR encounter times were on average 27 min longer for MAC cases (231 vs. 204 min, P < 0.001, d = 0.41).

Conclusion

MAC improves the utilization of IR procedure rooms, but at the cost of increased patient time in the pre- and post-procedure areas.

Imaging Considerations before and after Liver-Directed Locoregional Treatments for Metastatic Colorectal Cancer

Colorectal cancer is a leading cause of cancer-related death. Liver metastases will develop in over one-third of patients with colorectal cancer and are a major cause of morbidity and mortality. Even though surgical resection has been considered the mainstay of treatment, only approximately 20% of the patients are surgical candidates. Liver-directed locoregional therapies such as thermal ablation, Yttrium-90 transarterial radioembolization, and stereotactic body radiation therapy are pivotal in managing colorectal liver metastatic disease. Comprehensive pre- and post-intervention imaging, encompassing both anatomic and metabolic assessments, is invaluable for precise treatment planning, staging, treatment response assessment, and the prompt identification of local or distant tumor progression. This review outlines the value of imaging for colorectal liver metastatic disease and offers insights into imaging follow-up after locoregional liver-directed therapy.

Three-Dimensional Margin as a Predictor of Local Tumor Progression after Microwave Ablation: Intraprocedural versus 4-8-Week Postablation Assessment

PURPOSE

To evaluate the prognostic accuracy of intraprocedural and 4-8-week (current standard) post-microwave ablation zone (AZ) and margin assessments for prediction of local tumor progression (LTP) using 3-dimensional (3D) software.

MATERIALS AND METHODS

Data regarding 100 colorectal liver metastases (CLMs) in 75 patients were collected from 2 prospective fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT)-guided microwave ablation (MWA) trials. The target CLMs and theoretical 5- and 10-mm margins were segmented and registered intraprocedurally and at 4-8 weeks after MWA contrast-enhanced CT (or magnetic resonance [MR] imaging) using the same methodology and 3D software. Tumor and 5- and 10-mm minimal margin (MM) volumes not covered by the AZ were defined as volumes of insufficient coverage (VICs). The intraprocedural and 4-8-week post-MWA VICs were compared as predictors of LTP using receiver operating characteristic curve analysis.

RESULTS

The median follow-up time was 19.6 months (interquartile range, 7.97-36.5 months). VICs for 5- and 10-mm MMs were predictive of LTP at both time assessments. The highest accuracy for the prediction of LTP was documented with the intra-ablation 5-mm VIC (area under the curve [AUC], 0.78; 95% confidence interval, 0.66-0.89). LTP for a VIC of 6-10-mm margin category was 11.4% compared with 4.3% for >10-mm margin category (P < .001).

CONCLUSIONS

A 3D 5-mm MM is a critical endpoint of thermal ablation, whereas optimal local tumor control is noted with a 10-mm MM. Higher AUCs for prediction of LTP were achieved for intraprocedural evaluation than for the 4-8-week postablation 3D evaluation of the AZ.

The Importance of Optimal Thermal Ablation Margins in Colorectal Liver Metastases: A Systematic Review and Meta-Analysis of 21 Studies

BACKGROUND

Colorectal cancer (CRC) is the second most common cause of cancer-related deaths in the US. Thermal ablation (TA) can be a comparable alternative to partial hepatectomy for selected cases when eradication of all visible tumor with an ablative margin of greater than 5 mm is achieved. This systematic review and meta-analysis aimed to encapsulate the current clinical evidence concerning the optimal TA margin for local cure in patients with colorectal liver metastases (CLM).

METHODS

MEDLINE, EMBASE, and the CENTRAL databases were systematically searched from inception until 1 May 2023, in accordance with the PRISMA Guidelines. Measure of effect included the risk ratio (RR) with 95% confidence interval (CI) using the random-effects model.

RESULTS

Overall, 21 studies were included, comprising 2005 participants and 2873 ablated CLMs. TA with margins less than 5 mm were associated with a 3.6 times higher risk for LTP (n = 21 studies, RR: 3.60; 95% CI: 2.58-5.03; p-value < 0.001). When margins less than 5 mm were additionally confirmed by using 3D software, a 5.1 times higher risk for LTP (n = 4 studies, RR: 5.10; 95% CI: 1.45-17.90; p-value < 0.001) was recorded. Moreover, a thermal ablation margin of less than 10 mm but over 5 mm remained significantly associated with 3.64 times higher risk for LTP vs. minimal margin larger than 10 mm (n = 7 studies, RR: 3.64; 95% CI: 1.31-10.10; p-value < 0.001).

CONCLUSIONS

This meta-analysis solidifies that a minimal ablation margin over 5 mm is the minimum critical endpoint required, whereas a minimal margin of at least 10 mm yields optimal local tumor control after TA of CLMs.

Percutaneous image-guided ablation for hepatic metastases

The presence of hepatic metastases indicates advanced disease and is associated with significant morbidity and mortality, especially when the hepatic disease is not amenable to locoregional treatments. The primary tumour of origin, the distribution and extent of metastatic disease, the underlying liver reserve, the patient performance status and the presence of comorbidities are factors that determine whether a patient will benefit from hepatectomy or local curative-intent treatments. For patients with metastatic colorectal cancer, the most common primary cancer that spreads to the liver, several studies have demonstrated a survival benefit for patients who can be treated with hepatectomy and/or percutaneous ablation, compared to those treated with chemotherapy alone. Despite advances in surgical techniques increasing the percentage of patients eligible for surgery, most patients have unresectable disease or are poor surgical candidates. Percutaneous ablation can be used to provide local disease control and prolong survival for both surgical and non-surgical candidates. This is typically offered to patients with small hepatic metastases that can be ablated with optimal (≥10 mm) or at least adequate minimum ablation margins (≥5 mm), as high local tumour control rates can be achieved for these patients which are comparable to surgical resection. This review summarizes available evidence and outcomes following percutaneous ablation of the most frequently encountered types of hepatic metastases in the clinical practice of interventional oncology. Patient selection, technical considerations, follow-up protocols and oncologic outcomes are presented and discussed.

Factors affecting outcomes of Yttrium-90 radioembolization in heavily pretreated patients with intrahepatic cholangiocarcinoma

PURPOSE

Transarterial radioembolization (TARE) is a liver-directed treatment for unresectable intrahepatic cholangiocarcinoma (ICC). The aim of this study is to evaluate factors affecting outcomes of TARE in heavily pretreated ICC patients.

METHODS

We evaluated pretreated ICC patients who received TARE from January 2013 to December 2021. Prior treatments included systemic therapy, hepatic resection, and liver-directed therapies, including hepatic arterial infusion chemotherapy, external beam radiation, transarterial embolization, and thermal ablation. Patients were classified based on history of hepatic resection and genomic status based on next-generation sequencing (NGS). The primary endpoint was overall survival (OS) after TARE.

RESULTS

Fourteen patients with median age 66.1 years (range, 52.4-87.5), 11 females and 3 males, were included. Prior therapies included systemic in 13/14 patients (93%), liver resection in 6/14 (43%), and liver-directed therapy in 6/14 (43%). Median OS was 11.9 months (range, 2.8-81.0). Resected patients had significantly longer median OS compared to unresected patients (16.6 versus 7.9 months; p = 0.038). Prior liver-directed therapy (p = 0.043), largest tumor diameter > 4 cm (p = 0.014), and > 2 hepatic segments involvement (p = 0.001) were associated with worse OS. Nine patients underwent NGS; 3/9 (33.3%) and had a high-risk gene signature (HRGS), defined as alterations in TP53, KRAS, or CDKN2A. Patients with a HRGS had worse median OS (10.0 versus 17.8 months; p = 0.024).

CONCLUSIONS

TARE may be used as salvage therapy in heavily treated ICC patients. Presence of a HRGS may predict worse OS after TARE. Further investigation with more patients is recommended to validate these results.

Gradient-based Volumetric PET Parameters on Immediate Pre-ablation FDG-PET Predict Local Tumor Progression in Patients with Colorectal Liver Metastasis Treated by Microwave Ablation

PURPOSE

This study aimed to evaluate the optimal method of segmentation of colorectal liver metastasis (CLM) on immediate pre-ablation PET scans and assess the prognostic value of quantitative pre-ablation PET parameters with regards to local tumor control. A secondary objective was to correlate the target tumor size estimation by PET methods with the tumor measurements on anatomical imaging.

METHODOLOGY

A prospectively accrued cohort of 55 CLMs (46 patients) treated with real-time ¹⁸F-FDG-PET/CT-guided percutaneous microwave ablation was followed-up for a median of 10.8 months (interquartile: 5.5-20.2). Total lesion glycolysis (TLG) and metabolic tumor volume (MTV) values of each CLM were derived from pre-ablation ¹⁸F-FDG-PET with gradient and threshold PET segmentation methodologies. The event was defined as local tumor progression (LTP). Time-dependent receiver operating characteristic (ROC) curve analyses were used to assess area under the curves (AUCs). Intraclass correlation (ICC) and 95.0% confidence interval (CI) were performed to measure the linear relationships between the continuous variables.

RESULTS

AUCs for prediction of LTP obtained from time-dependent ROC analysis for the gradient technique were higher in comparison to the threshold methodologies (AUCs for TLG and volume were: 0.790 and 0.807, respectively). ICC between PET gradient-based and anatomical measurements were higher in comparison to threshold methodologies (ICC for the longest diameter: 733 (95.0% CI 0.538-0.846), ICC for the shortest diameter: .747 (95.0% CI 0.546-0.859), p-values < 0.001).

CONCLUSIONS

The gradient-based technique had a higher AUC for prediction of LTP after microwave ablation of CLM and showed the highest correlation with anatomical imaging tumor measurements.

Reducing Wait Times for Radiology Exams Around Holiday Periods: A Monte Carlo Simulation

Reducing patient wait times is a key operational goal and impacts patient outcomes. The purpose of this study is to explore the effects of different radiology scheduling strategies on exam wait times before and after holiday periods at an outpatient imaging facility using computer simulation. An idealized Monte Carlo simulation of exam scheduling at an outpatient imaging facility was developed based on the actual distribution of scheduled exams at outpatient radiology sites at a tertiary care medical center. Using this simulation, we examined three scheduling strategies: (1) no scheduling modifications, (2) increase imaging capacity before or after the holiday (i.e. increase facility hours), and (3) use a novel rolling release scheduling paradigm. In the third scenario, a fraction of exam slots are blocked to long-term follow-up exams and made available only closer to the exam date, thereby preventing long-term follow-up exams from filling the schedule and ensuring slots are available for non-follow-up exams. We examined the effect of these three scenarios on utilization and wait times, which we defined as the time from order placement to exam completion, during and after the holiday period. The baseline mean wait time for non-follow-up exams was 5.4 days in our simulation. When no scheduling modifications were made, there was a significant increase in wait times in the week preceding the holiday when compared to baseline (10.0 days vs 5.4 days, p < 0.01). Wait times remained elevated for 4 weeks following the holiday. Increasing imaging capacity during the holiday and post-holiday period by 20% reduced wait times by only 6.2% (9.38 days vs 10.0 days, p < 0.01). Increasing capacity by 50% resulted in a 7.1% reduction in wait times (9.28 days, p < 0.01), and increasing capacity by 100% resulted in a 13% reduction in wait times (8.75 days, p < 0.01). In comparison, using a rolling release model produced a reduction in peak wait times equivalent to doubling capacity (8.76 days, p < 0.01) when 45% of slots were reserved. Improvements in wait times persisted even when rolling release was limited to the 3 weeks preceding or 1 week following the holiday period. Releasing slots on a rolling basis did not significantly decrease utilization or increase wait times for long-term follow-up exams except in extreme scenarios where 80% or more of slots were reserved for non-follow-up exams. A rolling release scheduling paradigm can significantly reduce wait time fluctuations around holiday periods without requiring additional capacity or impacting utilization.

Real-Time Split-Dose PET/CT-Guided Ablation Improves Colorectal Liver Metastasis Detection and Ablation Zone Margin Assessments without the Need for Repeated Contrast Injection

BACKGROUND

Real-time split-dose PET can identify the targeted colorectal liver metastasis (CLM) and eliminate the need for repeated contrast administration before and during thermal ablation (TA). This study aimed to assess the added value of pre-ablation real-time split-dose PET when combined with non-contract CT in the detection of CLM for ablation and the evaluation of the ablation zone and margins.

METHODS

A total of 190 CLMs/125 participants from two IRB-approved prospective clinical trials using PET/CT-guided TA were analyzed. Based on detection on pre-TA imaging, CLMs were categorized as detectable, non-detectable, and of poor conspicuity on CT alone, and detectable, non-detectable, and low FDG-avidity on PET/CT after the initial dose. Ablation margins around the targeted CLM were evaluated using a 3D volumetric approach.

RESULTS

We found that 129/190 (67.9%) CLMs were detectable on CT alone, and 61/190 CLMs (32.1%) were undetectable or of poor conspicuity, not allowing accurate depiction and targeting by CT alone. Thus, the theoretical 5- and 10-mm margins could not be defined in these tumors (32.1%) using CT alone. When TA intraprocedural PET/CT images are obtained and inspected (fused PET/CT), only 4 CLM (2.1%) remained undetectable or had a low FDG avidity.

CONCLUSIONS

The addition of PET to non-contrast CT improved CLM detection for ablation targeting, margin assessments, and continuous depiction of the FDG avid CLMs during the ablation without the need for multiple intravenous contrast injections pre- and intra-procedurally.

Perfusion-only imaging in pregnant women: A comparative reader study with implications for practice patterns

This study seeks to understand the value of ventilation imaging in pregnant patients imaged for suspected pulmonary embolism (PE). Ventilation-perfusion (VQ) scans in this high-risk population were compared to ventilation-only scans. We hypothesize that in this relatively healthy population, the exclusion of ventilation scans will not impact the rate of scans interpreted as positive. This retrospective blinded comparative reader study on collated VQ scans performed on pregnant patients in the course of routine clinical care in a > 5 year period (03/2012 to 07/2017). Each set of VQ and perfusion only (Q) studies were reviewed by 8 readers (4 nuclear radiology fellows and 4 nuclear medicine faculty) in random order; the Q scans simply omitted the ventilation images. Readers recorded each study as PE, no PE, or non-diagnostic (prospective investigative study of acute PE diagnosis classifications). Logistic mixed effects models were used to test the association between scan type (VQ vs Q). 203 pairs of studies in 197 patients were included (6 patients had 2 scans). Subjects ranged from 14 to 45 years of age, with a median 28 years. A significant association between scan type and positive/negative classification. Q-scans received more positive classifications than VQ-scans (median of 7.6% vs 6.7%). No association was seen between scan type and positive/indeterminate classification, nor between scan type and negative/indeterminate classification. The exclusion of ventilation images in VQ-scans was associated with a higher rate of positive studies, but this difference was small (<1%). Given the overwhelmingly normal percentage of Q-exams (>90% in our study), and the benefits of omitting ventilation imaging, perfusion-only imaging should be considered a reasonable option for imaging the pregnant patient to exclude PE.

Immunofluorescence Assay of Ablated Colorectal Liver Metastases: The Frozen Section of Image-Guided Tumor Ablation?

PURPOSE

To validate an immunofluorescence assay (IFA) detecting residual viable tumor (VT) as intraprocedural thermal ablation (TA) zone assessment and demonstrate its prognostic value for local tumor progression (LTP) after colorectal liver metastasis (CLM) TA.

MATERIALS AND METHODS

This prospective study, approved by the institutional review board, included 99 patients with 155 CLMs ablated between November 2009 and January 2019. Tissue samples from the ablation zone (AZ) center and minimal margin underwent immunofluorescent microscopic examination interrogating cellular morphology and mitochondrial viability (IFA) within 30 minutes after ablation. The same tissue samples were subsequently evaluated with standard morphologic and immunohistochemical methods. The sensitivity, specificity, and overall accuracy of IFA versus standard morphologic and immunohistochemical examination were calculated. The LTP-free survival rates were evaluated for the 12-month follow-up period.

RESULTS

Of the 311 tissue samples stained, 304 (98%) were deemed evaluable. Of these specimens, 27% (81/304) were considered positive for the presence of VT. The accuracy of IFA was 94% (286/304). The sensitivity and specificity were 100% (63/63) and 93% (223/241), respectively. The 18 false-positive IFA assessments corresponded to samples that included viable cholangiocytes. The 12-month LTP-free survival was 59% versus 78% for IFA positive versus negative for VT AZs, respectively (P < .001). There was no difference in LTP between margin positive only and central AZ-positive tumors (25% vs 31%, P = 1).

CONCLUSIONS

The IFA assessment of the AZ can be completed intraprocedurally and serve as a valid real-time biomarker of complete tumor eradication or detect residual VT after TA. This method could improve tumor control by TA.

Magnification Spot Radiographs Improve Assessment for Inferior Vena Cava Filter Fractures prior to Removal Compared to CT

PURPOSE

To determine if magnification spot radiographs acquired before attempting inferior vena cava (IVC) filter removal have value in the assessment for filter fractures.

MATERIALS AND METHODS

A retrospective review of complex IVC filter removals performed at a tertiary referral center from October 2015 to May 2017 was performed. Magnification spot radiographs (frontal and at least 2 oblique views) were obtained with the fluoroscopic unit in the procedure suite prior to venous access for filter removal. Patients were included in the study if a computed tomography (CT) scan of the abdomen/pelvis before filter removal was available. Ninety-six patients (47 women and 49 men) were included. Most removed filters were the Recovery/G2/G2X/Eclipse/Meridian (n = 28), the Günther Tulip (n = 26), and the Celect/Celect Platinum (n = 22). Blinded review of the pre-procedural CT scans and spot radiographs for the presence of filter fractures was performed by 2 interventional radiologists. Accuracy of each modality was assessed using the status of the explanted filter as the gold standard. Agreement between the 2 readers was assessed with the kappa statistic.

RESULTS

Fractures were present in 27 explanted filters (28%). Accuracy of CT was 88% and 68% for readers 1 and 2, respectively, which increased to 98% and 97% with magnification spot radiographs. The kappa statistic was 0.12 for CT and 0.97 for spot radiographs.

CONCLUSIONS

Magnification spot radiographs acquired before attempting IVC filter removal improve detection of filter fractures and agreement among interventional radiologists. Therefore, these should be performed routinely to allow for optimal treatment planning.

Fluorescent Tissue Assessment of Colorectal Cancer Liver Metastases Ablation Zone: A Potential Real-Time Biomarker of Complete Tumor Ablation

BACKGROUND

This study aimed to evaluate whether rapid fluorescent tissue examination immediately after colorectal cancer liver metastasis (CLM) ablation correlates with standard pathologic and immunohistochemical (IHC) assessments.

METHODS

This prospective, National Institutes of Health-supported study enrolled 34 consecutive patients with 53 CLMs ablated between January 2011 and December 2014. Immediately after ablation, core needle sampling of the ablation zone was performed. Tissue samples were evaluated with fluorescent viability (MitoTracker Red) and nuclear (Hoechst) stains. Confocal microscope imaging was performed within 30 min after ablation. The same samples were subsequently fixed and stained with hematoxylin and eosin (H&E). Identified tumor cells underwent IHC staining for proliferation (Ki67) and viability (OxPhos). The study pathologist, blinded to the H&E and IHC assessment, evaluated the fluorescent images separately to detect viable tumor cells. Sensitivity, specificity, and overall concordance of the fluorescent versus H&E and IHC assessments were calculated.

RESULTS

A total of 63 tissue samples were collected and processed. The overall concordance rate between the immediate fluorescent and the subsequent H&E and IHC assessments was 94% (59/63). The fluorescent assessment sensitivity and specificity for the identification of tumor cells were respectively 100% (18/18) and 91% (41/45).

CONCLUSIONS

The study showed a high concordance rate between the immediate fluorescent assessment and the standard H&E and IHC assessment of the ablation zone. Given the documented prognostic value of ablation zone tissue characteristics for outcomes after ablation of CLM, the fluorescent assessment offers a potential intra-procedural biomarker of complete tumor ablation.

Colorectal Cancer Liver Metastases: Biopsy of the Ablation Zone and Margins Can Be Used to Predict Oncologic Outcome

Purpose To establish the prognostic value of biopsy of the central and marginal ablation zones for time to local tumor progression (LTP) after radiofrequency (RF) ablation of colorectal cancer liver metastasis (CLM). Materials and Methods A total of 47 patients with 67 CLMs were enrolled in this prospective institutional review board-approved and HIPAA-compliant study between November 2009 and August 2012. Mean tumor size was 2.1 cm (range, 0.6-4.3 cm). Biopsy of the center and margin of the ablation zone was performed immediately after RF ablation (mean number of biopsy samples per ablation zone, 1.9) and was evaluated for the presence of viable tumor cells. Samples containing tumor cells at morphologic evaluation were further interrogated with immunohistochemistry and were classified as either positive, viable tumor (V) or negative, necrotic (N). Minimal ablation margin size was evaluated in the first postablation CT study performed 4-8 weeks after ablation. Variables were evaluated as predictors of time to LTP with the competing-risks model (uni- and multivariate analyses). Results Technical effectiveness was evident in 66 of 67 (98%) ablated lesions on the first contrast material-enhanced CT images at 4-8-week follow-up. The cumulative incidence of LTP at 12-month follow-up was 22% (95% confidence interval [CI]: 12, 32). Samples from 16 (24%) of 67 ablation zones were classified as viable tumor. At univariate analysis, tumor size, minimal margin size, and biopsy results were significant in predicting LTP. When these variables were subsequently entered in a multivariate model, margin size of less than 5 mm (P < .001; hazard ratio [HR], 6.7) and positive biopsy results (P = .008; HR, 3.4) were significant. LTP within 12 months after RF ablation was noted in 3% (95% CI: 0, 9) of necrotic CLMs with margins of at least 5 mm. Conclusion Biopsy proof of complete tumor ablation and minimal ablation margins of at least 5 mm are independent predictors of LTP and yield the best oncologic outcomes. (©) RSNA, 2016.

Radioembolization as a Salvage Therapy for Heavily Pretreated Patients With Colorectal Cancer Liver Metastases: Factors That Affect Outcomes

BACKGROUND

In this study we assessed the efficacy and factors that affect outcomes of radioembolization (RE) using yttrium-90 resin microspheres in patients with unresectable and chemorefractory colorectal cancer liver metastases (CLM).

PATIENTS AND METHODS

After an institutional review board waiver of approval, a review of a Health Insurance Portability and Accountability Act-registered, prospectively created and maintained database was performed. Data on patient demographic and disease characteristics, RE treatment parameters, and additional treatments were evaluated for significance in predicting overall survival (OS) and liver progression-free survival (LPFS). Complications were evaluated according to the National Cancer Institute Common Terminology Criteria for adverse events.

RESULTS

From September 2009 to September 2013, 53 patients underwent RE at a median of 35 months after CLM diagnosis. Median OS was 12.7 months. Multivariate analysis showed that carcinoembryonic antigen levels at the time of RE ≥ 90 ng/mL (P = .004) and microscopic lymphovascular invasion of the primary (P = .002) were independent predictors of decreased OS. Median LPFS was 4.7 months. At 4 to 8 and 12 to 16 weeks after RE, most patients (80% and 61%, respectively) according to Response Evaluation Criteria in Solid Tumors (RECIST) had stable disease; additional evaluation using PET Response Criteria in Solid Tumors (PERCIST) led to reclassification in 77% of these cases (response or progression). No deaths were noted within the first 30 days. Within the first 90 days after RE, 4 patients (8%) developed liver failure and 5 patients (9%) died, all with evidence of disease progression.

CONCLUSION

RE in the salvage setting was well-tolerated, and permitted the administration of additional therapies and led to a median OS of 12.7 months. Evaluation using PERCIST was more likely than RECIST to document response or progression compared with the baseline assessment before RE.