Regression of liver metastases following treatment with yttrium-90 microspheres

Ytrrium-90 transarterial radioembolization in patients with gastrointestinal malignancies

Transarterial radioembolization (TARE) with yttrium-90 (Y90) is a promising alternative strategy to treat liver tumors and liver metastasis from colorectal cancer (CRC), as it selectively delivers radioactive isotopes to the tumor via the hepatic artery, sparring surrounding liver tissue. The landscape of TARE indications is constantly evolving. This strategy is considered for patients with hepatocellular carcinoma (HCC) with liver-confined disease and preserved liver function in whom neither TACE nor systemic therapy is possible. In patients with liver metastases from CRC, TARE is advised when other chemotherapeutic options have failed. Recent phase III trials have not succeeded to prove benefit in overall survival; however, it has helped to better understand the patients that may benefit from TARE based on subgroup analysis. New strategies and treatment combinations are being investigated in ongoing clinical trials. The aim of this review is to summarize the clinical applications of TARE in patients with gastrointestinal malignancies.

In vivo tumour imaging employing regional delivery of novel gallium radiolabelled polymer composites

Background

Understanding the regional vascular delivery of particles to tumour sites is a prerequisite for developing new diagnostic and therapeutic composites for treatment of oncology patients. We describe a novel imageable ⁶⁷Ga-radiolabelled polymer composite that is biocompatible in an animal tumour model and can be used for preclinical imaging investigations of the transit of different sized particles through arterial networks of normal and tumour-bearing organs.

Results

Radiolabelling of polymer microspheres with ⁶⁷Ga was achieved using a simple mix and wash method, with tannic acid as an immobilising agent. Final in vitro binding yields after autoclaving averaged 94.7%. In vivo stability of the composite was demonstrated in New Zealand white rabbits by intravenous administration, and intrahepatic artery instillations were made in normal and VX2 tumour implanted rabbit livers. Stability of radiolabel was sufficient for rabbit lung and liver imaging over at least 3 hours and 1 hour respectively, with lung retention of radiolabel over 91%, and retention in both normal and VX2 implanted livers of over 95%. SPECT-CT imaging of anaesthetised animals and planar imaging of excised livers showed visible accumulation of radiolabel in tumours. Importantly, microsphere administration and complete liver dispersal was more easily achieved with 8 μm diameter MS than with 30 μm MS, and the smaller microspheres provided more distinct and localised tumour imaging.

Conclusion

This method of producing ⁶⁷Ga-radiolabelled polymer microspheres is suitable for SPECT-CT imaging of the regional vascular delivery of microspheres to tumour sites in animal models. Sharper distinction of model tumours from normal liver was obtained with smaller MS, and tumour resolution may be further improved by the use of ⁶⁸Ga instead of ⁶⁷Ga, to enable PET imaging.

History and development of radioembolization: an old idea with modern applications

The current review documents the major hallmarks in the history and development of radioembolization, the origins of which date back to the late 1940s. Radioembolization was initially abandoned because of the increased incidence of adverse effects and lack of commercial interest; however, it regained avid interest in clinical trials and has achieved established clinical utility in the last 15 years. This review focuses on the main stations of the evolution of radioembolization, namely, initial animal and human experimental studies, production of Y-microspheres, development of current therapeutic agents (resin and glass spheres and labeled Lipiodol), prediction and prevention of inadvertent, extrahepatic shunt side effects, initial prospective studies, and large randomized trials till final approval from the relevant official bodies. The historical knowledge of the initial concepts of the method and the limitations encountered may pave the way toward further evolution and possible new applications.

99mTc-radiolabeled composites enabling in vivo imaging of arterial dispersal and retention of microspheres in the vascular network of rabbit lungs, liver, and liver tumors

Purpose

Selective internal radiation therapy (SIRT) is an effective treatment option for liver tumors, using Y-90-loaded polymer microspheres that are delivered via catheterization of the hepatic artery. Since Y-90 is a beta emitter and not conveniently imaged by standard clinical instrumentation, dosimetry is currently evaluated in each patient using a surrogate particle, ^99mTechnetium-labeled macroaggregated albumin (^99mTc-MAA). We report a new composite consisting of ^99mTc-labeled nanoparticles attached to the same polymer microspheres as used for SIRT, which can be imaged with standard SPECT.

Methods

Carbon nanoparticles with an encapsulated core of ^99mTc were coated with the polycation protamine sulfate to provide electrostatic attachment to anionic polystyrene sulfonate microspheres of different sizes (30, 12, and 8 µm). The in vivo stability of these composites was determined via intravenous injection and entrapment in the capillary network of normal rabbit lungs for up to 3 hours. Furthermore, we evaluated their biodistribution in normal rabbit livers, and livers implanted with VX2 tumors, following intrahepatic artery instillation.

Results

We report distribution tests for three different sizes of radiolabeled microspheres and compare the results with those obtained using ^99mTc-MAA. Lung retention of the radiolabeled microspheres ranged from 72.8% to 92.9%, with the smaller diameter microspheres showing the lowest retention. Liver retention of the microspheres was higher, with retention in normal livers ranging from 99.2% to 99.8%, and in livers with VX2 tumors from 98.2% to 99.2%. The radiolabeled microspheres clearly demonstrated preferential uptake at tumor sites due to the increased arterial perfusion produced by angiogenesis.

Conclusion

We describe a novel use of radiolabeled carbon nanoparticles to generate an imageable microsphere that is stable in vivo under the shear stress conditions of arterial networks. Following intra-arterial instillation in the normal rabbit liver, they distribute in a distinct segmented pattern, with the smaller microspheres extending throughout the organ in finer detail, while still being well retained within the liver. Furthermore, in livers hosting an implanted VX2 tumor, they reveal the increased arterial perfusion of tumor tissue resulting from angiogenesis. These novel composites may have potential as a more representative mimic of the vascular distribution of therapeutic microspheres in patients undergoing SIRT.

History and Evolution of Yttrium-90 Radioembolization for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer and affects millions worldwide. Due to the lack of effective systemic therapies for HCC, researchers have been investigating the use of locoregional tumor control with Yttrium-90 (Y90) radioembolization since the 1960s. Following the development of glass and resin Y90 microspheres in the early 1990s, Y90 radioembolization has been shown to be a safe and efficacious treatment for patients with HCC across Barcelona Clinic Liver Cancer (BCLC) stages. By demonstrating durable local control, good long term outcomes, and equivalent if not superior tumor responses and tolerability when compared to alternative therapies including transarterial chemoembolization (TACE) and sorafenib, Y90 radioembolization is being increasingly used in HCC treatment. More recently, investigations into variations in Y90 radioembolization technique including radiation segmentectomy and radiation lobectomy have further expanded its clinical utility. Here, we discuss the history and evolution of Y90 use in HCC. We outline key clinical trials that have established the safety and efficacy of Y90 radioembolization, and also summarize trials comparing its efficacy to existing HCC treatments. We conclude by reviewing the techniques of radiation segmentectomy and lobectomy, and by discussing dosimetry.

The development, commercialization, and clinical context of yttrium-90 radiolabeled resin and glass microspheres

Selective internal radiation therapy has emerged as a well-accepted therapeutic for primary and metastatic hepatic malignancies. This therapeutic modality requires the combined efforts of multiple medical disciplines to ensure the safe delivery of yttrium-90 (90Y)-labeled microspheres. The development of this therapy followed decades of clinical research involving tumor vascularity and microsphere development. Today, it is essential that treating physicians have a thorough understanding of hepatic tumor vascularity and 90Y microsphere characteristics before undertaking this complex intervention. This review explores the contributions of early investigators of this therapy, as well as the development, US Food and Drug Administration approval, manufacturing process, and attributes of the 2 commercially available 90Y radiolabeled microsphere device to clarify the key physical differences between the products.

Outcomes and Predictors of Toxicity after Selective Internal Radiation Therapy Using Yttrium-90 Resin Microspheres for Unresectable Hepatocellular Carcinoma

Purpose

We sought to report outcomes and toxicity in patients with hepatocellular carcinoma (HCC) who received resin yttrium-90 selective internal radiation therapy (⁹⁰Y-SIRT) and to identify factors associated with declining liver function.

Methods

Patients treated with ⁹⁰Y-SIRT were retrospectively evaluated. Radiographic response was assessed using RECIST 1.1. Median liver progression-free survival (LPFS) and overall survival (OS) were calculated using the Kaplan–Meier method. Bivariate analysis was used to examine associations between change in Child-Pugh (CP) score/class and patient characteristics and treatment parameters.

Results

Twenty-seven patients with unresectable HCC underwent SIRT, 52% were CP Class A, 48% were Class B, 11% were BCLC stage B, and 89% were stage C. Forty-four percent of patients had portal vein thrombus at baseline. One-third of patients received bilobar treatment. Median activity was 32.1 mCi (range 9.18–43.25) and median-­absorbed dose to the liver was 39.6 Gy (range 13.54–67.70). Median LPFS and OS were 2.5 and 11.7 months, respectively. Three-month disease control rate was 63 and 52% in the target lesions and whole liver, respectively. New onset or worsened from baseline clinical toxicities were confined to Grade 1–2 events. However, new or worsened Grade 3–4 laboratory toxicities occurred in 38% of patients at 3 months and 43% of patients at 6 months following SIRT (six had lymphocytopenia, three had hypoalbuminemia, and two had transaminasemia). After 3 months, six patients had worsened in CP score and five had worsened in class from baseline. After 6 months, four patients had worsened in CP score and one had worsened in class from baseline. Pretreatment bilirubinemia was associated with a 2+ increase in CP score within 3 months (P = 0.001) and 6 months (P = 0.039) of ⁹⁰Y-SIRT. Pretreatment transaminasemia and bilirubinemia were associated with increased CP class within 3 months of SIRT (P = 0.021 and 0.009, respectively).

Conclusion

⁹⁰Y-SIRT was well-tolerated in patients with unresectable HCC, with no Grade 3–4 clinical toxicities. However, Grade 3–4 laboratory toxicities and worsened CP scores were more frequent. HCC patients with pretreatment bilirubinemia or transaminasemia may be at higher risk of experiencing a decline in liver function following ⁹⁰Y-SIRT.

SPIO-labeled Yttrium Microspheres for MR Imaging Quantification of Transcatheter Intrahepatic Delivery in a Rodent Model

PURPOSE

To investigate the qualitative and quantitative impacts of labeling yttrium microspheres with increasing amounts of superparamagnetic iron oxide (SPIO) material for magnetic resonance (MR) imaging in phantom and rodent models.

MATERIALS AND METHODS

Animal model studies were approved by the institutional Animal Care and Use Committee. The r2* relaxivity for each of four microsphere SPIO compositions was determined from 32 phantoms constructed with agarose gel and in eight concentrations from each of the four compositions. Intrahepatic transcatheter infusion procedures were performed in rats by using each of the four compositions before MR imaging to visualize distributions within the liver. For quantitative studies, doses of 5, 10, 15, or 20 mg 2% SPIO-labeled yttrium microspheres were infused into 24 rats (six rats per group). MR imaging R2* measurements were used to quantify the dose delivered to each liver. Pearson correlation, analysis of variance, and intraclass correlation analyses were performed to compare MR imaging measurements in phantoms and animal models.

RESULTS

Increased r2* relaxivity was observed with incremental increases of SPIO microsphere content. R2* measurements of the 2% SPIO-labeled yttrium microsphere concentration were well correlated with known phantom concentrations (R(2) = 1.00, P < .001) over a broader linear range than observed for the other three compositions. Microspheres were heterogeneously distributed within each liver; increasing microsphere SPIO content produced marked signal voids. R2*-based measurements of 2% SPIO-labeled yttrium microsphere delivery were well correlated with infused dose (intraclass correlation coefficient, 0.98; P < .001).

CONCLUSION

MR imaging R2* measurements of yttrium microspheres labeled with 2% SPIO can quantitatively depict in vivo intrahepatic biodistribution in a rat model.

A computational tool for patient specific dosimetry and radiobiological modeling of selective internal radiation therapy with (90)Y microspheres

In recent years we have witnessed tremendous progress in selective internal radiation therapy. In clinical practice, quite often, radionuclide therapy is planned using simple models based on standard activity values or activity administered per unit body weight or surface area in spite of the admission that radiation-dose methods provide more accurate dosimetric results. To address that issue, the authors developed a Matlab-based computational software, named Patient Specific Yttrium-90 Dosimetry Toolkit (PSYDT). PSYDT was designed for patient specific voxel-based dosimetric calculations and radiobiological modeling of selective internal radiation therapy with (90)Y microspheres. The developed toolkit is composed of three dimensional dose calculations for both bremsstrahlung and beta emissions. Subsequently, radiobiological modeling is performed on a per-voxel basis and cumulative dose volume histograms (DVHs) are generated. In this report we describe the functionality and visualization features of PSYDT.

(90)Y-glass microspheres for hepatic neoplasia

Unresectable liver cancer presents a major problem in the treatment of solid tumors. Transarterial radioembolization is a modern approach toward primary and secondary liver malignancies. The mechanism of action is independent from other therapies that are based on ischemia or chemotoxicity. (90)Y-resin and (90)Y-glass microspheres are commercially available for transarterial radioembolization. Available data on the use of (90)Y-glass microspheres in hepatocellular carcinoma and metastatic disease indicate that this treatment is safe and effective. In hepatocellular carcinoma the results compare well with chemoembolization and might be considered more often. Current data in metastatic disease are promising, but there is a strong need for prospective randomized trials to identify the role of transarterial radioembolization with (90)Y-glass microspheres in metastatic liver disease.

Fusion dual-tracer SPECT-based hepatic dosimetry predicts outcome after radioembolization for a wide range of tumour cell types

Purpose

Fusion dual-tracer SPECT imaging enables physiological rather than morphological voxel-based partitioning and dosimetry for ⁹⁰Y hepatic radioembolization (RE). We evaluated its prognostic value in a large heterogeneous cohort of patients with extensive hepatic malignancy.

Methods

A total of 122 patients with primary or secondary liver malignancy (18 different cell types) underwent SPECT imaging after intraarterial injection of ^99mTc macroaggregated albumin (TcMAA) as a simulation of subsequent ⁹⁰Y microsphere distribution, followed by administration of an excess of intravenous ^99mTc-labelled sulphur colloid (TcSC) as a biomarker for functional liver, and a second SPECT scan. TcMAA distribution was used to estimate ⁹⁰Y radiation absorbed dose in tumour (D_T) and in functional liver. Laboratory and clinical follow-up were recorded for 12 weeks after RE, and radiographic responses according to (m)RECIST were evaluated at 3 and 6 months. Dose–response relationships were determined for efficacy and toxicity.

Results

Patients were treated with a median of 1.73 GBq activity of resin microspheres (98 patients) or glass microspheres (24 patients), in a whole-liver approach (97 patients) or a lobar approach (25 patients). The objective response rate was 41 % at 3 months and 48 % at 6 months. Response was correlated with D_T (P < 0.01). Median overall survival was 10.1 months (95 % confidence interval 7.4 – 12.8 months). Responders lived for 36.0 months compared to 8.7 months for nonresponders (P < 0.01). Stratified for tumour cell type, D_T was independently associated with survival (P < 0.01). Absorbed dose in functional liver was correlated with toxicity grade change (P < 0.05) and RE-induced liver disease (P < 0.05).

Conclusion

Fusion dual-tracer SPECT imaging offers a physiology-based functional imaging tool to predict efficacy and toxicity of RE. This technique can be refined to define dosing thresholds for specific tumour types and treatments, but appears generally predictive even in a heterogeneous cohort.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-015-3048-z) contains supplementary material, which is available to authorized users.

Transarterial therapies for primary liver tumors

Over the last decade, transarterial therapies have gained worldwide acceptance as standard of care for inoperable primary liver cancer. Survival times after transarterial chemoembolization (TACE) continue to improve as the technique and selection criteria are refined. Transarterial treatments, frequently provided in an outpatient setting, are now safely and effectively being applied to patients with even advanced malignancy or partially decompensated cirrhosis. In the coming years, newer transarterial therapies such as radiation segmentectomy, boosted-transarterial radioembolzation, combined TACE-ablation, TACE-portal vein embolization, and transarterial infusion of cancer-specific metabolic inhibitors promise to continue improving survival and quality of life.

Selective Interarterial Radiation Therapy (SIRT) in Colorectal Liver Metastases: How Do We Monitor Response?

Radioembolisation is a way of providing targeted radiotherapy to colorectal liver metastases. Results are encouraging but there is still no standard method of assessing the response to treatment. This paper aims to review the current experience assessing response following radioembolisation. A literature review was undertaken detailing radioembolisation in the treatment of colorectal liver metastases comparing staging methods, criteria, and response. A search was performed of electronic databases from 1980 to November 2011. Information acquired included year published, patient numbers, resection status, chemotherapy regimen, criteria used to stage disease and assess response to radioembolisation, tumour markers, and overall/progression free survival. Nineteen studies were analysed including randomised controlled trials, clinical trials, meta-analyses, and case series. There is no validated modality as the method of choice when assessing response to radioembolisation. CT at 3 months following radioembolisation is the most frequently modality used to assess response to treatment. PET-CT is increasingly being used as it measures functional and radiological aspects. RECIST is the most frequently used criteria. Conclusion. A validated modality to assess response to radioembolisation is needed. We suggest PET-CT and CEA pre- and postradioembolisation at 3 months using RECIST 1.1 criteria released in 2009, which includes criteria for PET-CT, cystic changes, and necrosis.

Rho guanine nucleotide exchange factors: regulators of Rho GTPase activity in development and disease

The aberrant activity of Ras homologous (Rho) family small GTPases (20 human members) has been implicated in cancer and other human diseases. However, in contrast to the direct mutational activation of Ras found in cancer and developmental disorders, Rho GTPases are activated most commonly in disease by indirect mechanisms. One prevalent mechanism involves aberrant Rho activation via the deregulated expression and/or activity of Rho family guanine nucleotide exchange factors (RhoGEFs). RhoGEFs promote formation of the active GTP-bound state of Rho GTPases. The largest family of RhoGEFs is comprised of the Dbl family RhoGEFs with 70 human members. The multitude of RhoGEFs that activate a single Rho GTPase reflects the very specific role of each RhoGEF in controlling distinct signaling mechanisms involved in Rho activation. In this review, we summarize the role of Dbl RhoGEFs in development and disease, with a focus on Ect2 (epithelial cell transforming squence 2), Tiam1 (T-cell lymphoma invasion and metastasis 1), Vav and P-Rex1/2 (PtdIns(3,4,5)P3 (phosphatidylinositol (3,4,5)-triphosphate)-dependent Rac exchanger).

Patient dosimetry for 90Y selective internal radiation treatment based on 90Y PET imaging

Until recently, the radiation dose to patients undergoing the 90Y selective internal radiation treatment (SIRT) procedure is determined by applying the partition model to 99mTc MAA pretreatment scan. There can be great uncertainty in radiation dose calculated from this approach and we presented a method to compute the 3D dose distributions resulting from 90Y SIRT based on 90Y positron emission tomography (PET) imaging. Five 90Y SIRT treatments were retrospectively analyzed. After 90Y SIRT, patients had 90Y PET/CT imaging within 6 hours of the procedure. To obtain the 3D dose distribution of the patients, their respective 90Y PET images were convolved with a Monte Carlo generated voxel dose kernel. The sensitivity of the PET/CT scanner for 90Y was determined through phantom studies. The 3D dose distributions were then presented in DICOM RT dose format. By applying the linear quadratic model to the dose data, we derived the biologically effective dose and dose equivalent to 2 Gy/fraction delivery, taking into account the spatial and temporal dose rate variations specific for SIRT. Based on this data, we intend to infer tumor control probability and risk of radiation induced liver injury from SIRT by comparison with established dose limits. For the five cases, the mean dose to target ranged from 51.7 ± 28.6 Gy to 163 ± 53.7 Gy. Due to the inhomogeneous nature of the dose distribution, the GTVs were not covered adequately, leading to very low values of tumor control probability. The mean dose to the normal liver ranged from 21.4 ± 30.7 to 36.7 ± 25.9 Gy. According to QUANTEC recommendation, a patient with primary liver cancer and a patient with metastatic liver cancer has more than 5% risk of radiotherapy-induced liver disease (RILD).

Donor-transmitted malignancy in a liver transplant recipient: a case report and review of literature

Donor-transmitted malignancy is a rare complication of organ transplantation. This case illustrates a donor-transmitted adenocarcinoma in a patient 11 months after an orthotopic liver transplant for cryptogenic cirrhosis and hepatocellular carcinoma (HCC). Diagnosis of donor-transmitted malignancy may be challenging and can be confused with HCC recurrence. A timely diagnosis is crucial as a delay may limit treatment options. Biopsy of newly found liver lesions and the use of karyotypic and microsatellite analysis may be essential for diagnosis. Protocols should be in place to help recognize and limit the incidence of donor-transmitted malignancy.

Treatment advances in liver-limited metastatic colorectal cancer

Over the last several decades advances in the management and treatment of patients with liver metastases from colorectal cancer (CRC) has changed a disease with a dismal prognosis to one with a potential for cure in some patients. Advances have been made through coordinated management of patients by surgeons, medical oncologists, radiologists, and other health care professionals coupled with advances in treatment options. Although these advances have clearly impacted patient outcomes, it is clear that the benefit of traditional surgical approaches and the use of cytoxic chemotherapy are reaching a plateau. Continued research to develop new and more active therapies, including targeted or biologic agents, is needed. This review discusses the advances made in management of patients with liver-limited metastatic disease.

Radioembolization of yttrium-90 microspheres for hepatic malignancy

The liver represents a frequent site for primary and secondary neoplasia. Cytoreductive techniques positively influence the outcome of disease progression in these patients. Transhepatic arterial radioembolotherapy utilizing yttrium-90 microspheres represents a recently available in situ therapy that has shown encouraging results in the treatment of these patients. Harnessing the skills of many different specialties, such as interventional radiology, surgical oncology, medical oncology, nuclear medicine, radiation oncology, medical physics, and radiation safety, brings invaluable expertise to the treatment process for a safe and effective radioembolization treatment program.

Yttrium-90 radioembolization for colorectal cancer liver metastases: a single institution experience

Purpose. We sought to evaluate our experience using yttrium-90 (⁹⁰Y) resin microsphere hepatic radioembolization as salvage therapy for liver-dominant metastatic colorectal cancer (mCRC). Methods. A retrospective review of consecutive patients with unresectable mCRC who were treated with ⁹⁰Y after failing first and second line systemic chemotherapy. Demographics, treatment dose, biochemical and radiographic response, toxicities, and survival were examined. Results. Fifty-one patients underwent ⁹⁰Y treatments of which 69% were male. All patients had previously undergone extensive chemotherapy, 31% had undergone previous liver-directed therapy and 24% had a prior liver resection. Using RECIST criteria, either stable disease or a partial response was seen in 77% of patients. Overall median survival from the time of first ⁹⁰Y treatment was 10.2 months (95% CI = 7.5–13.0). The absence of extrahepatic disease at the time of treatment with ⁹⁰Y was associated with an improved survival, median survival of 17.0 months (95% CI = 6.4–27.6), compared to those with extrahepatic disease at the time of treatment with ⁹⁰Y, 6.7 months (95% CI = 2.7–10.6 Conclusion: ⁹⁰Y therapy is a safe locoregional therapy that provides an important therapeutic option to patients who have failed first and second line chemotherapy and have adequate liver function and performance status.

Selective internal radiation therapy for gastrointestinal neuroendocrine tumour liver metastases: a new and effective modality for treatment

Background. Nonresectable neuroendocrine tumour (NET) liver metastases respond poorly to most widely available and used therapies. Selective Internal Radiation Therapy (SIRT) is becoming recognized as a new modality for selectively treating non-resectable liver tumours. This paper presents an experience of 14 patients with non-resectable NET liver metastases treated with SIRT. Methods. Between September 1997 and October 2009 14 patients with extensive NET liver metastases were treated with 2.0 to 3.0 GBq of (90)Yttrium microspheres. Repeat SIRT was undertaken in three patients after 16, 27, and 48 months, respectively. Responses were assessed clinically, biochemically, and with serial CT scans. Survival was measured from initial SIRT. Results. Some response was seen in all 14 patients. Carcinoid syndrome improved or resolved in 10/10 instances. 24-hour urinary 5-HIAA or serum chromogranin A levels fell dramatically in 5/7 patients following SIRT. Serial CT scans revealed partial response or stable disease in all 14 patients. Repeat treatment in three patients experiencing progression was associated with a further response. Median survival after SIRT is 25 months with 6 patients being alive (and 3 patients still asymptomatic), at 19, 22, 23, 23, 58, and 60 months. Conclusions. SIRT is an effective and well-tolerated treatment for non-resectable NET liver metastases capable of both alleviating the carcinoid syndrome and achieving significant tumour regression. Repeat treatment is an option and liver resection after downstaging may also become possible.

Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography predicts extrahepatic metastatic potential of colorectal metastasis: a practical guide for yttrium-90 microsphere liver-directed therapy

The objective of this retrospective study was to assess the likelihood of extrahepatic metastases based on tumor metabolic load index (TMLI) for patients with colorectal liver metastases to determine the potential intermediate endpoint of yttrium-90 (Y-90) microsphere liver-directed therapy. Forty-eight (48) patients with colorectal metastatic cancer of the liver who were referred for Y-90 microsphere therapy and F-18 fluoro-2-deoxy-D-glucose positron emission tomography (PET) imaging were included. All patients had baseline computed tomography, hepatic angiography, and planning intra-arterial technetium-99m macro-aggregated albumin scans. Pretreatment PET images were analyzed by visual inspection of extrahepatic metastases and by computer quantification of total liver tumor metabolism. For each patient, regions of interest were drawn along the liver edge to measure total liver standard uptake value on axial images, covering the entire span of the liver. The total liver standard uptake value was then converted by logarithm in equivalent volumes of liver mass to obtain TMLI for comparison. A Levene test for equality of variances and t-tests were used for comparing pretreatment TMLIs of patients with or without extrahepatic metastasis. Discriminant and receiver operating characteristic (ROC) analyses were used to obtain a cutoff value with highest specificity in predicting negative extrahepatic metastasis. There were 21 and 27 patients identified as negative and positive for extrahepatic metastasis, respectively. The TMLI of the group with negative extrahepatic metastasis was significantly lower than that with positive extrahepatic metastasis (10.22 + 0.32 versus 10.74 + 0.57, p < 0.0005). The cutoff TMLI with 100% specificity was found to be 10.65. There was a significant difference in liver tumor load with respect to the presence or absence of an extrahepatic metastatic tumor as evaluated objectively with PET. This leads to the identification of TMLI threshold, below which extrahepatic metastases are unlikely and thus may provide guidance for Y-90 therapy.

Radioembolization (yttrium-90 microspheres) for primary and metastatic hepatic malignancies

Radioembolization using radioactive yttrium-90-labeled microspheres is gaining a stronger foothold in the management of primary and metastatic hepatic cancers. The expanding literature reveals good and encouraging results in both retrospective and prospective reports as demonstrated by low acute or late toxicity and high response rates. This treatment modality, which is most beneficial in patients with good liver reserve and low Eastern Cooperative Oncology Group performance status, has led to improved time to liver progression and extended overall patient survival. Although the phase III trials of radioembolization are ongoing as a first-line treatment of patients with metastatic colorectal cancer, there are sufficient phase II and retrospective clinical data supporting its use in salvage therapy for most patients. Patients with hepatocellular cancer, neuroendocrine tumors, and other primary sites, including breast and lung, have also shown promising response and survival increases in multi-institutional experiences.

Preparation of porous yttrium oxide microparticles by gelation of ammonium alginate in aqueous solution containing yttrium ions

Porous Y2O3 microparticles 500 microm in size were obtained, when 1 wt%-ammonium alginate aqueous solution was dropped into 0.5 M-YCl3 aqueous solution by a Pasteur pipette and the resultant gel microparticles were heat-treated at 1100 degrees C. Small pores less than 1 microm were formed in the microparticles by the heat treatment. The bulk density of the heat-treated microparticle was as low as 0.66 g cm(-3). The chemical durability of the heat-treated microparticles in simulated body fluid at pH = 6 and 7 was high enough for clinical application of in situ radiotherapy. Although the size of the microparticles should be decreased to around 25 microm using atomizing device such as spray gun for clinical application, we found that the porous Y2O3 microparticles with high chemical durability and low density can be obtained by utilizing gelation of ammonium alginate in YCl3 aqueous solution in this study.

Yttrium-90 radioembolization for liver malignancies: prognostic factors associated with survival

PURPOSE

To identify key prognostic clinical and imaging variables in patients undergoing yttrium-90 radioembolization ((90)Y) for liver malignancies.

MATERIALS AND METHODS

Patients with liver malignancies that progressed despite standard-of-care therapy were treated with (90)Y from 2002 to 2006. Baseline functional status, laboratory values, and diagnostic imaging were assessed before therapy. Imaging follow-up was performed 1 month after treatment and subsequently at 3-month intervals. Patients were followed for survival from the time of their first (90)Y treatment.

RESULTS

Patients with follow-up imaging after radioembolization (N = 130) were included in this analysis. Primary malignancies included colon, neuroendocrine, and others. The following clinical variables had a significant effect on survival on multivariate analysis: Eastern Cooperative Oncology Group (ECOG) performance status (PS) greater than 0 (hazard ratio [HR], 7.98; 95% CI, 3.98-16), hepatic tumor burden of 51%-75% (HR, 2.46; 95% CI, 1.01-6.02), bilirubin level greater than 1.3 mg/dL (HR, 2.60; 95% CI, 1.27-5.34), hepatic metastases from breast cancer (HR, 2.51; 95% CI, 1.13-5.61), response on imaging based on World Health Organization (WHO) criteria (HR, 0.48; 95% CI, 0.24-0.94), and lymphocyte depression (HR, 0.56; 95% CI, 0.31-0.96). Among patients with colorectal cancer metastases to the liver, the HR for survival on univariate analysis for responders compared with nonresponders (per WHO criteria) was 0.26 (95% CI, 0.10-0.69).

CONCLUSIONS

Cancer-related symptoms (ie, ECOG PS > 0), hepatic tumor burden greater than 50%, increased bilirubin levels, and hepatic metastases from breast cancer were found to be negative prognostic factors. Tumor response to therapy and lymphocyte depression were associated with favorable prognosis. Additionally, WHO response was identified to be a favorable prognostic factor in patients with colorectal cancer metastases. These findings may be useful when counseling patients regarding prognosis of their hepatic disease.

Liver metastases from colorectal cancer: radioembolization with systemic therapy

The majority of patients with advanced colorectal cancer die from hepatic metastases caused by disease progression; therefore, several novel technologies are in clinical development to potentially improve local control of liver disease. Radioembolization is a technique for administering radiotherapy internally to unresectable primary or secondary hepatic malignancies in a single procedure. This technique involves the injection of resin or glass microspheres that contain (90)Y into the arterial supply of the liver. Clinical trials of radioembolization used with concomitant radiosensitizing chemotherapy have shown promising results in patients with metastatic colorectal cancer. Several reports suggest that radioembolization is associated with significant downsizing of liver metastases to permit subsequent surgical resection. In this article, the rationale for combining radioembolization with the cytotoxic and molecularly targeted agents licensed for the systemic treatment of colorectal cancer is outlined. Clinical data from trials of radioembolization with concomitant systemic treatment are reviewed, with an emphasis on the appropriateness of primary end points in large-scale trials and the practical aspects of surgical resection in patients whose tumors are successfully downsized by this chemoradiation approach.

[Liver tumor ablation]

Minimal-invasive techniques for ablation of primary and secondary hepatic tumors gain increasingly clinical importance. This is especially true since surgical resection and classic chemotherapy is successful only in a limited number of patients. Local ablative methods incorporate chemo- (percutaneous alcohol instillation, transarterial chemoembolization), thermo- (radiofrequency-, laser-, microwave-, cryoablation, high intensive focused ultrasound) and radio-ablative techniques (interstitial brachytherapy, selective internal radiotherapy). Regarding their implementation and specific effects these methods are varying widely, nevertheless all of them have a high therapeutical efficacy together with a low complication rate in common-correct application presumed. The knowledge on specific indications and contraindications is crucial to implement these methods into multimodality therapy concepts.

Yttrium-90 microsphere radioembolization for the treatment of liver malignancies: a structured meta-analysis

Radioembolization with yttrium-90 microspheres ((90)Y-RE), either glass- or resin-based, is increasingly applied in patients with unresectable liver malignancies. Clinical results are promising but overall response and survival are not yet known. Therefore a meta-analysis on tumor response and survival in patients who underwent (90)Y-RE was conducted. Based on an extensive literature search, six groups were formed. Determinants were cancer type, microsphere type, chemotherapy protocol used, and stage (deployment in first-line or as salvage therapy). For colorectal liver metastases (mCRC), in a salvage setting, response was 79% for (90)Y-RE combined with 5-fluorouracil/leucovorin (5-FU/LV), and 79% when combined with 5-FU/LV/oxaliplatin or 5-FU/LV/irinotecan, and in a first-line setting 91% and 91%, respectively. For hepatocellular carcinoma (HCC), response was 89% for resin microspheres and 78% for glass microspheres. No statistical method is available to assess median survival based on data presented in the literature. In mCRC, (90)Y-RE delivers high response rates, especially if used neoadjuvant to chemotherapy. In HCC, (90)Y-RE with resin microspheres is significantly more effective than (90)Y-RE with glass microspheres. The impact on survival will become known only when the results of phase III studies are published.

Regional infusion-radioembolization

Selective internal radiation therapy involves the intra-arterial delivery of radioactive beads to the tumor while minimizing dosing to the adjacent organ. Because this technique invariably results in some degree of embolization, it has also been termed radioembolization. More than 8000 patients have been treated worldwide, with a large body of experience with primary hepatocellular carcinoma (HCC) and metastatic colorectal carcinoma (MCRC) and growing experience with other tumors (metastatic neuroendocrine, breast carcinoma, cholangiocarcinoma). Response rates by FDG-PET are 80% to 90%. Complications are uncommon and most often consist of self-limited malaise. More significant complications, including radiation-induced liver disease, ischemic cholecystitis, and gastrointestinal ulceration may be seen in up to 10% of patients. This underscores the critical importance of patient selection and meticulous technique. Median survival times in patients who have HCC and MCRC are significantly improved compared with historic controls. Further study is required to determine the appropriate role of radioembolization in the context of state-of-the-art chemotherapy and other liver-directed therapies.

Unresectable chemorefractory liver metastases: radioembolization with 90Y microspheres--safety, efficacy, and survival

PURPOSE

To prospectively evaluate the safety, efficacy, and survival of patients with chemorefractory liver metastases who have been treated with yttrium 90 ((90)Y) glass microspheres.

MATERIALS AND METHODS

Institutional review boards from two institutions approved the HIPAA-compliant study; all patients provided informed consent. One hundred thirty-seven patients underwent 225 administrations of (90)Y microspheres by using intraarterial infusion. Primary sites (origins) included colon, breast, neuroendocrine, pancreas, lung, cholangiocarcinoma, melanoma, renal, esophageal, ovary, adenocarcinoma of unknown primary, lymphoma, gastric, duodenal, bladder, angiosarcoma, squamous cell carcinoma, thyroid, adrenal, and parotid. Patients underwent evaluation of baseline and follow-up liver function and tumor markers and computed tomographic or magnetic resonance imaging. Patients were observed for survival from first treatment. Median survival (in days) and corresponding 95% confidence intervals were computed by using the Kaplan-Meier method. The log-rank statistic was used for statistical significance testing of survival distributions between various subgroups of patients.

RESULTS

There were 66 men and 71 women. All patients were treated on an outpatient basis. Median age was 61 years. The mean number of treatments was 1.6. The median activity and dose infused were 1.83 GBq and 112.8 Gy, respectively. Clinical toxicities included fatigue (56%), vague abdominal pain (26%), and nausea (23%). At follow-up imaging, according to World Health Organization criteria, there was a 42.8% response rate (2.1% complete response, 40.7% partial response). There was a biologic tumor response (any decrease in tumor size) of 87%. Overall median survival was 300 days. One-year survival was 47.8%, and 2-year survival was 30.9%. Median survival was 457 days for patients with colorectal tumors, 776 days for those with neuroendocrine tumors, and 207 days for those with noncolorectal, nonneuroendocrine tumors.

CONCLUSION

(90)Y hepatic treatments are well tolerated with acceptable toxicities; tumor response and median survival are promising.

Hepatic yttrium-90 radioembolotherapy in metastatic colorectal cancer treated with cetuximab or bevacizumab

Yttrium-90 microspheres have been recently approved by the Food and Drug Administration and have become available to physicians in the United States for the treatment of hepatic neoplasia. Published results regarding the benefits of 90Y radioembolotherapy within the rapidly evolving landscape of systemic therapies for advanced unresectable colorectal cancer are limited. In that context, outcomes in patients who have received the recently approved biologic agents bevacizumab and cetuximab in addition to chemotherapy are unknown. This report briefly describes the authors' treatment experience with this cohort of patients.

Multimodality imaging following 90Y radioembolization: a comprehensive review and pictorial essay

Radioembolization with yttrium 90 (90Y) microspheres represents an emerging transarterial therapy for the treatment of liver malignancies that continues to generate interest in the medical community. The classic indication of treatment response is a reduction in tumor size; however, parenchymal changes (eg, necrosis, lack of enhancement, specific findings at positron emission tomography and functional magnetic resonance imaging) and other benign findings (pleural effusions, perivascular edema, contralateral hypertrophy, ring enhancement, perihepatic fluid, fibrosis) may occur following treatment, requiring proper image interpretation. With classic imaging findings and surrogates (time to progression, duration of response, disease-free interval), response rates range from 20% to 80% in patients treated for hepatocellular carcinoma or metastatic disease to the liver. Complications of 90Y radioembolization include cholecystitis, abscess, and bilomas and should be recognized early in the imaging follow-up of these patients. Radiologists who are involved in the posttreatment assessment of patients undergoing 90Y radioembolization should be familiar with the imaging findings and potential imaging pitfalls associated with this therapy.

Optimizing the approach to patients with potentially resectable liver metastases from colorectal cancer

Liver metastases are a common event in colorectal carcinoma. Significant advances have been made in managing these patients in the last decade, including improvements in staging and surgical techniques, an increasing armamentarium of chemotherapeutics and multiple local ablative techniques. While combination chemotherapy significantly improves median patient survival, surgical resection provides the only prospect of cure and is the focus of this review. Interpretation of published work in this field is challenging, particularly as there is no consensus to what is resectable disease. Of particular interest recently has been the use of neoadjuvant treatment for downstaging and downsizing disease in patients with initially unresectable liver metastases, in the hope of response leading to potentially curative surgery. This review summarizes the recent developments and consensus guidelines in the areas of staging, chemotherapy, local ablative techniques, radiation therapy and surgery, emphasizing the multidisciplinary approach to this disease and ongoing controversies in this field and examines the changing paradigms in the management of colorectal hepatic metastases.