Response of liver metastases after treatment with yttrium-90 microspheres: role of size, necrosis, and PET

Imaging of Neuroendocrine Neoplasms; Principles of Treatment Strategies. What Referring Clinicians Want to Know

ABSTRACT

Neuroendocrine neoplasms (NENs) are a diverse group of tumors that express neuroendocrine markers and primarily affect the lungs and digestive system. The incidence of NENs has increased over time due to advancements in imaging and diagnostic techniques. Effective management of NENs requires a multidisciplinary approach, considering factors such as tumor location, grade, stage, symptoms, and imaging findings. Treatment strategies vary depending on the specific subtype of NEN. In this review, we will focus on treatment strategies and therapies including the information relevant to clinicians in order to undertake optimal management and treatment decisions, the implications of different therapies on imaging, and how to ascertain their possible complications and treatment effects.

Advancements in Neuroendocrine Neoplasms: Imaging and Future Frontiers

Neuroendocrine neoplasms (NENs) are a diverse group of tumors with varying clinical behaviors. Their incidence has risen due to increased awareness, improved diagnostics, and aging populations. The 2019 World Health Organization classification emphasizes integrating radiology and histopathology to characterize NENs and create personalized treatment plans. Imaging methods like CT, MRI, and PET/CT are crucial for detection, staging, treatment planning, and monitoring, but each of them poses different interpretative challenges and none are immune to pitfalls. Treatment options include surgery, targeted therapies, and chemotherapy, based on the tumor type, stage, and patient-specific factors. This review aims to provide insights into the latest developments and challenges in NEN imaging, diagnosis, and management.

The Role of 18F-FLT PET/CT in Assessing Early Response to Transarterial Radioembolization and Chemoembolization in Patients with Primary and Metastatic Liver Tumors

Objectives

Metastases and primary malignancies are common in the liver. Local ablative applications such as transarterial chemoembolization (TACE), and transarterial radioembolization (TARE) provide minimally invasive and safe treatment in unresectable liver tumors. Early detection of response to treatment prevents unnecessary toxicity and cost in non-responder patients and provides an earlier use of other options that may be effective. This study aimed to identify the role of ¹⁸F-fluorothymidine (FLT) positron emission tomography/computed tomography (PET/CT) in the assessment of early response to TACE and TARE treatments in patients with unresectable primary and metastatic liver tumors.

Methods

This single-center study included 63 patients who underwent ¹⁸F-FLT PET/CT for response evaluation after TACE and TARE. After excluding 20 patients whose data were missing 43 TARE-receiving patients were analyzed. The compatibility of change in semi-quantitative values obtained from the ¹⁸F-FLT PET/CT images with the treatment responses detected in ¹⁸F-fluorodeoxyglucose PET/CT, CT, and MR images and survival was evaluated.

Results

There was no correlation between early metabolic, morphological response, and ¹⁸F-FLT uptake pattern, and change in standardized uptake values (SUV) which were ΔSUV_max, ΔSUV_mean, ΔSUV_peak., ΔSUV_mean, Δ SUV_peak values. There was no significant correlation between ¹⁸F-FLT uptake pattern, ΔSUV_max, ΔSUV_mean, ΔSUV_peak, and overall survival, progression-free survival (PFS) for the target lobe PFS for the whole-body. The survival distributions for the patients with >30% change in Δ SUV_max and ΔSUV_peak values were statistically significantly longer than the patients with <30% change (p<0.009 and p<0.024, respectively).

Conclusion

There was significant longer PFS for target liver lobe in patients with more than 30% decrease in ¹⁸F-FLT SUV_max and SUV_peak of the liver lesion in primary and metastatic unresectable liver tumors undergoing TARE.

Evolution of Radioembolization in Treatment of Hepatocellular Carcinoma: A Pictorial Review

Transarterial radioembolization (TARE) with yttrium 90 has increasingly been performed to treat hepatocellular carcinoma (HCC). TARE was historically used as a palliative lobar therapy for patients with advanced HCC beyond surgical options, ablation, or transarterial chemoembolization, but recent advancements have led to its application across the Barcelona Clinic Liver Cancer staging paradigm. Newer techniques, termed radiation lobectomy and radiation segmentectomy, are being performed before liver resection to facilitate hypertrophy of the future liver remnant, before liver transplant to bridge or downstage to transplant, or as a definite curative treatment. Imaging assessment of therapeutic response to TARE is challenging as the intent of TARE is to deliver local high-dose radiation to tumors through microembolic microspheres, preserving blood flow to promote radiation injury to the tumor. Because of the microembolic nature, early imaging assessment after TARE cannot rely solely on changes in size. Knowledge of the evolving methods of TARE along with the tools to assess posttreatment imaging and response is essential to optimize TARE as a therapeutic option for patients with HCC. ^©RSNA, 2021.

Treatment response assessment following transarterial radioembolization for hepatocellular carcinoma

Transarterial radioembolization with yttrium-90 microspheres is an established therapy for hepatocellular carcinoma. Post-procedural imaging is important for the assessment of both treatment response and procedural complications. A variety of challenging treatment-specific imaging phenomena complicate imaging assessment, such as changes in tumoral size, tumoral and peritumoral enhancement, and extrahepatic complications. A review of the procedural steps, emerging variations, and timelines for post-treatment tumoral and extra-tumoral imaging changes are presented, which may aid the reporting radiologist in the interpretation of post-procedural imaging. Furthermore, a description of post-procedural complications and their significance is provided.

Yttrium-90 Portal Vein Radioembolization in Sprague-Dawley Rats: Dose-Dependent Imaging and Pathological Changes in Normal Liver

PURPOSE

Portal vein embolization (PVE) is an established neoadjuvant method to induce future liver remnant hypertrophy prior to surgical resection of hepatic tumors. The purpose of our study was to examine the feasibility of PVE with glass ⁹⁰Y microspheres (Y90 PVE) in Sprague-Dawley rats. We tested the hypothesis that increased doses of Y90 PVE would increase target lobe fibrosis and atrophy.

METHODS

Twenty-two rats were assigned to four groups for Y90 PVE to the right median lobe: very high- (273.8 MBq; n = 2), high- (99.9 MBq; n = 10), medium- (48.1 MBq; n = 5), and low-dose (14.8 MBq; n = 5). An untreated control group included seven rats. ⁹⁰Y PET/CT of ⁹⁰Y distributions confirmed lobar targeting. MRI volumes were measured at baseline, 2-, 4-, 8- and 12-weeks. Explanted hepatic lobes were weighed, sectioned, and stained for H&E and immunohistochemistry. Digitized slides allowed quantitative measurements of fibrosis (20 foci/slide).

RESULTS

Ex vivo measurements confirmed 91-97% activity was localized to the target lobe (n = 4). The percent growth of the target lobe relative to baseline was - 5.0% (95% CI - 17.0-6.9%) for high-, medium dose rats compared to + 18.6% (95% CI + 7.6-29.7%) in the low-dose group at 12-weeks (p = 0.0043). Radiation fibrosis increased in a dose-dependent fashion. Fibrotic area/microsphere was 22,893.5, 14,946.2 ± 2253.3, 15,304.5 ± 4716.6, and 5268.8 ± 2297.2 μm² for very high- (n = 1), high- (n = 4), medium- (n = 3), and low-dose groups (n = 5), respectively.

CONCLUSION

Y90 PVE was feasible in the rat model, resulted in target lobe atrophy, and dose-dependent increases in hepatic fibrosis at 12 weeks. The onset of imaging-based volumetric changes was 8-12 weeks.

Factors affecting the response to Y-90 microsphere therapy in the cholangiocarcinoma patients

OBJECTIVE

The aim of this study was to assess the early therapy response in patients with unresectable CCA who received Y-90 microsphere therapy for CCA and define the factors related to therapy response.

MATERIALS AND METHODS

Data of 19 patients [extrahepatic (n: 6) and intrahepatic (n: 13)] who received 24 sessions of Y-90 microsphere therapy [glass (n: 13) and resin (n: 11)] were retrospectively evaluated. Tumor load, tumor size, therapy response evaluation by RECIST1.1 criteria (n: 13), tumor lesion glycolysis (TLG), metabolic tumor volume (MTV), and metabolic therapy responses were evaluated (n: 8) using PERCIST1.0 criteria.

RESULTS

No significant relation was found between therapy response and tumor localization, treated liver lobe, type of Y90 microspheres, the presence of previous therapies, perfusion pattern on hepatic artery perfusion scintigraphy, or patient demographics. The mean overall survival (OS) was 11.9 ± 2.3 months and was similar after both resin and glass Y90 microspheres; however, it was longer RECIST responders (p: 0.005). MTV and TLG values significantly decreased after therapy, and ΔMTV (- 45.4% ± 12.1) was found to be positively correlated with OS. No statistical difference was found between iCCA and eCCA, in terms of OS and response to therapy. Although not quantitatively displayed, better-perfused areas on HAPS images had a better metabolic response and less perfused areas were prone to local recurrences.

CONCLUSIONS

Both resin and glass microsphere therapy can be applied safely to iCCA and eCCA patients. Early therapy response can be evaluated with both RECIST and PERCIST criteria. Both anatomical and metabolic therapy response evaluations give complementary information.

Establishment and validation of a risk prediction model in patients with hepatocellular carcinoma treated with transarterial radioembolization

BACKGROUND/AIMS

Few studies have reported the treatment outcomes of transarterial radioembolization (TARE) using yttrium-90 (Y) for hepatocellular carcinoma (HCC). We established and validated a new risk prediction model for patients with HCC treated with TARE.

METHODS

Between 2010 and 2017, 113 and 35 patients with intrahepatic HCC treated with TARE were selected for the training and validation cohorts, respectively. The modified response evaluation criteria in solid tumors (mRECIST) were used for response evaluation.

RESULTS

In the training cohort, the median age was 64.1 years (92 males and 21 females) and the mean survival after TARE was 50.3 months. The cumulative survival rates at six and 12 months were 92.0 and 84.0%, respectively. A new risk prediction model for patients with HCC treated with TARE (Y-scoring system) was established from the training cohort using five independent baseline variables [serum albumin < 3.5 g/dL, hazard ratio = 5.446; alpha-fetoprotein > 200 ng/mL (hazard ratio = 5.071); tumor number ≥ 3 (hazard ratio = 2.933); portal vein thrombosis (hazard ratio = 4.915); and hepatic vein invasion (hazard ratio = 8.500)] and two on-treatment variables [no des-gamma-carboxy prothrombin response (hazard ratio = 15.346) and progressive disease at three months (hazard ratio = 4.154)] for mortality (all P < 0.05). The predictive accuracy of the Y-scoring system was acceptable to predict six [area under the curve (AUC) = 0.845], nine (AUC = 0.868), and 12-month mortality (AUC = 0.886) (all P < 0.05). The predictive accuracy of the system was similarly maintained in the validation cohort (AUC 0.737-0.901 at 6-12 months).

CONCLUSION

Our new risk prediction model can be used to stratify different prognoses in patients with HCC treated with TARE. Validation studies are required.

MRI Assessment of Hepatocellular Carcinoma after Local-Regional Therapy: A Comprehensive Review

Nearly 80% of cirrhotic patients diagnosed with hepatocellular carcinoma (HCC) are not eligible for surgical resection and instead undergo local-regional treatment. After therapy for HCC, patients undergo imaging surveillance to assess treatment efficacy and identify potential sites of progressive tumor elsewhere within the liver. Accurate interpretation of posttreatment imaging is essential for guiding further management decisions, and radiologists must understand expected treatment-specific imaging findings for each of the local-regional therapies. Of interest, expected imaging findings seen after radiation-based therapies (transarterial radioembolization and stereotactic body radiation therapy) are different than those seen after thermal ablation and transarterial chemoembolization. Given differences in expected posttreatment imaging findings, the current radiologic treatment response assessment algorithms used for HCC (modified Response Evaluation Criteria in Solid Tumors classification, European Association for the Study of Liver Diseases criteria, and Liver Imaging and Reporting Data System Treatment Response Algorithm) must be applied cautiously for radiation-based therapies in which persistent arterial phase hyperenhancement in the early posttreatment period is common and expected. This article will review the concept of tumor response assessment for HCC, the forms of local-regional therapy for HCC, and the expected posttreatment findings for each form of therapy. Keywords: Abdomen/GI, Liver, MR-Imaging, Treatment Effects, Tumor Response © RSNA, 2020.

Evaluation of Early Response to Treatment of Hepatocellular Carcinoma with Yttrium-90 Radioembolization Using Quantitative Computed Tomography Analysis

Objective

To identify an imaging predictor for the assessment of early treatment response to yttrium-90 transarterial radioembolization (TARE) in patients with hepatocellular carcinoma (HCC), using a quantitative assessment of dynamic computed tomography (CT) images.

Materials and Methods

Dynamic contrast-enhanced CT was obtained pre- and 4 weeks post-TARE in 44 patients (34 men, 10 women; mean age, 60 years) with HCC. Computer software was developed for measuring the percentage increase in the combined delayed-enhancing area and necrotic area (pD + N) and the percentage increase in the necrotic area (pNI) in the tumor-containing segments pre- and post-TARE. Local progression-free survival (PFS) was compared between patient groups using Cox regression and Kaplan-Meier analyses.

Results

Post-TARE HCC with pD + N ≥ 35.5% showed significantly longer PFS than those with pD + N < 35.5% (p = 0.001). The local tumor progression hazard ratio was 17.3 (p = 0.009) for pD + N < 35.5% versus pD + N ≥ 35.5% groups. HCCs with a high pNI tended to have longer PFS, although this difference did not reach statistical significance.

Conclusion

HCCs with a larger pD + N are less likely to develop local progression after TARE.

Assessment of Treatment Response Following Yttrium-90 Transarterial Radioembolization of Liver Malignancies

Transarterial radioembolization using yttrium-90 microspheres is an established and effective treatment for liver malignancies. Determining response to this treatment is difficult due to the radical changes that occur in tissue as a response to radiation. Though accurate assessment of treatment response is paramount for proper patient disposition, there is currently no standardized assessment protocol. Current methods of assessment often consider changes in size, necrosis, vascularity, fluorodeoxyglucose-positron emission tomography FDG-PET metabolic activity, and diffusion using diffusion-weighted magnetic resonance imaging (DWI). Current methods of assessment require a lag time of one to two months post-treatment to determine treatment effectiveness. This delay is a hindrance to obtaining better patient outcomes, giving rise to a need to identify markers for faster determination of treatment efficacy.

Imaging Evaluation Following 90Y Radioembolization of Liver Tumors: What Radiologists Should Know

Radioembolization using beta-emitting yttrium-90 microspheres is being increasingly used for the treatment of primary and metastatic liver cancers. It is a form of intra-arterial brachytherapy which delivers intense radiation to liver tumors with little embolic effect; this mode of action results in unique post-treatment imaging findings. It is important to understand these imaging findings to avoid misinterpretation of tumor response and to determine further management of the disease. Herein, we discuss the current concepts for assessing tumor response, common post-treatment imaging features, and associated complications following radioembolization.

Liver transarterial embolizations in metastatic neuroendocrine tumors

The management of patients with well-differentiated neuroendocrine tumors (NET) and non-resectable liver metastases is challenging. Liver-directed transarterial embolization (TAE), transarterial chemo-embolization (TACE) and selective internal radiation therapy (SIRT) have a place of choice among other treatment modalities. However, their utilization relies on a low level of proof, due to the lack of prospective data, the absence of comparative studies and considerable heterogeneity between local practices. TAE and TACE generally achieve average symptomatic, biological and radiological responses of 75%, 56% and 50%, with progression-free survival of 12-18 months, with acceptable tolerance. Although not clearly demonstrated, TACE may be more effective than TAE in pancreatic NET, but not in small-intestine NET. SIRT has been developed more recently and may achieve similar results, with improved tolerance, but decreased cost-effectiveness, although no prospective comparison has been published to date. There is currently no strong argument to choose between TAE, TACE and SIRT, and they have not been compared to other treatment modalities. The evaluation of their efficacy has mostly relied on criteria based on size variations, which do not take into account tumor viability and metabolism, and thus may not be relevant. These techniques may be especially effective when performed as first-line therapies, in patients with non-major liver involvement (<75%) and with hypervascular metastases. Finally, studies exploring their combination with systemic therapies are ongoing.

Prevention and treatment of complications of selective internal radiation therapy: Expert guidance and systematic review

Selective internal radiation therapy (or radioembolization) by intra-arterial injection of radioactive yttrium-90-loaded microspheres is increasingly used for the treatment of patients with liver metastases or primary liver cancer. The high-dose beta-radiation penetrates an average of only 2.5 mm from the source, thus limiting its effects to the site of delivery. However, the off-target diversion of yttrium-90 microspheres to tissues other than the tumor may lead to complications. The most prominent of these complications include radiation gastritis and gastrointestinal ulcers, cholecystitis, radiation pneumonitis, and radioembolization-induced liver disease, which may occur despite careful pretreatment planning. Thus, selective internal radiation therapy demands an expert multidisciplinary team approach in order to provide comprehensive care for patients. This review provides recommendations to multidisciplinary teams on the optimal medical processes in order to ensure the safe delivery of selective internal radiation therapy. Based on the best available published evidence and expert opinion, we recommend the most appropriate strategies for the prevention, early diagnosis, and management of potential radiation injury to the liver and to other organs. (Hepatology 2017;66:969-982).

Prognostic Importance of the Presence of Early Metabolic Response and Absence of Extrahepatic Metastasis After Selective Internal Radiation Therapy in Colorectal Cancer Liver Metastasis

AIMS

In this study, the authors aimed to identify prognostic factors after selective internal radiation therapy (SIRT) for colorectal cancer (CRC) liver metastasis.

METHODS

Forty-nine (28 male, 21 female; mean age: 64.6 ± 10.8) patients who received SIRT for CRC liver metastasis were studied. Effects of number (<5 vs. ≥5), maximum dimension, and standardized uptake value (SUV) of liver metastases, liver tumor load (<25% vs. 26%-50% vs. 51%-75%), presence of extrahepatic disease, and metabolic early response on overall survival were analyzed.

RESULTS

Mean follow-up time was 44.1 ± 27.5 months. Overall survival time was calculated as 10.03 ± 1.61 (95% CI; 6.86-13.20) months. SUV (0.004) of liver metastases, early metabolic response (p = 0.015), and presence of extrahepatic metastasis (p = 0.001) were identified as significant factors influencing overall survival. The hazard ratio was 1:2.3 for the presence of extrahepatic metastasis and 1:2.7 for the absence of early metabolic response.

CONCLUSION

These findings suggest that patients with CRC liver metastasis who have lower SUV at presentation and early metabolic response have better outcomes after SIRT.

Transarterial Therapy for Colorectal Liver Metastases

Until recently, hepatic arterial therapies (HAT) had been used for colorectal liver metastases after failure of first-, second-, and third-line chemotherapies. HAT has gained greater acceptance in patients with liver-dominant colorectal metastases after failure of surgery or systemic chemotherapy. The current data demonstrate that HAT is a safe and effective option for preoperative downsizing, optimizing the time to surgery, limiting non-tumor-bearing liver toxicity, and improving overall survival after surgery in patients with colorectal liver-only metastases. The aim of this review is to present the current data for HAT in liver-only and liver-dominant colorectal liver metastases.

Quantitative volumetric functional MR imaging: an imaging biomarker of early treatment response in hypo-vascular liver metastasis patients after yttrium-90 transarterial radioembolization

PURPOSE

To evaluate the value of quantitative volumetric functional MR imaging in early assessment of response to yttrium-90-labeled ((90)Y) transarterial radioembolization (TARE) in patients with hypo-vascular liver metastases.

MATERIALS AND METHODS

Seventy four metastatic lesions in 14 patients with hypo-vascular liver metastases after TARE were included in this retrospective study. Diffusion and contrast-enhanced MR imaging was performed before and early after treatment. All MR images were analyzed by two experienced radiologists. Response by anatomic metrics (RECIST, mRECIST, EASL) and functional metrics (ADC and arterial and venous enhancement) were reported in targeted and non-targeted lesions. A two-sample paired t test was used to compare the changes after TARE. A p value of <0.05 was considered statistically significant.

RESULTS

The anatomic metrics did not show any significant changes in both targeted and non-targeted groups. Targeted lesions demonstrated an increase in mean volumetric ADC (23.4%; p = 0.01), a decrease in arterial and venous enhancement (-22.9% and -6.7%, respectively; p < 0.001 and p = 0.002, respectively) 1 month after treatment. Twenty one responding lesions (42%) by RECIST at 6 months demonstrated a significant increase in volumetric ADC (37.2%; p = 0.01), decrease in arterial and venous enhancement (-58.5% and -23.9%, respectively; p < 0.001) at 1 month post-treatment. Responding lesions did not change significantly by anatomic metrics.

CONCLUSIONS

RECIST, mRECIST, and EASL criteria failed to stratify lesions into responders and non-responders early after TARE in hypo-vascular liver metastasis. Quantitative volumetric functional MR imaging could be a promising tool as a biomarker for predicting early response and can potentially be utilized in clinical trials.

Surrogate Imaging Biomarkers of Response of Colorectal Liver Metastases After Salvage Radioembolization Using 90Y-Loaded Resin Microspheres

OBJECTIVE

The purpose of the present study is to evaluate Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, tumor attenuation criteria, Choi criteria, and European Organization for Research and Treatment of Cancer (EORTC) PET criteria as measures of response and subsequent predictors of liver progression-free survival (PFS) after radioembolization (RE) of colorectal liver metastases (CLM). The study also assesses interobserver variability for measuring tumor attenuation using a single 2D ROI on a simple PACS workstation.

MATERIALS AND METHODS

We performed a retrospective review of the clinical RE database at our institution, to identify patients treated in the salvage setting for CLM between December 2009 and March 2013. Response was evaluated on FDG PET scans, with the use of EORTC PET criteria, and on portal venous phase CT scans, with the use of RECIST 1.1, tumor attenuation criteria, and Choi criteria. Two independent blinded observers measured tumor attenuation using a single 2D ROI. The intraclass correlation coefficient (ICC) for interobserver variability was assessed. Kaplan-Meier methodology was used to calculate liver PFS, and the log-rank test was used to assess the response criteria as predictors of liver PFS.

RESULTS

A total of 25 patients with 46 target tumors were enrolled in the study. The ICC was 0.95 at baseline and 0.98 at response evaluation. Among the 25 patients, more responders (i.e., partial response) were identified on the basis of EORTC PET criteria (n = 14), Choi criteria (n = 15), and tumor attenuation criteria (n = 13) than on the basis of RECIST 1.1 (n = 2). The median liver PFS was 3.0 months (95% CI, 2.1-4.0 months). Response identified on the basis of EORTC PET criteria (p < 0.001), Choi criteria (p < 0.001), or tumor attenuation criteria (p = 0.01) predicted liver PFS; however, response identified by RECIST 1.1 did not (p = 0.1).

CONCLUSION

RECIST 1.1 has poor sensitivity for detecting metabolic responses classified by EORTC PET criteria. EORTC PET criteria, Choi criteria, and tumor attenuation criteria appear to be equally reliable surrogate imaging biomarkers of liver PFS after RE in patients with CLM.

Threshold for Enhancement in Treated Hepatocellular Carcinoma on MDCT: Effect on Necrosis Quantification

OBJECTIVE

The objective of our study was to determine whether the conventionally used enhancement threshold of 10 HU for assessing tumor viability in treated hepatocellular carcinoma (HCC) lesions is valid.

MATERIALS AND METHODS

To distinguish pseudoenhancement from enhancement in a tumor, we used an in vivo model: The attenuation of 54 hepatic cysts during the unenhanced and portal venous phases of MDCT, similar to what may be observed in HCC with central necrosis, was used to determine the threshold for pseudoenhancement. To validate this model, we compared the attenuation value of liver parenchyma in this cohort with that of 22 HCCs during the late arterial phase of enhancement. We tested the effect of this pseudoenhancement on quantifying necrosis in HCC compared with the conventionally used threshold of 10 HU.

RESULTS

Values of enhancing HCC tissue on arterial phase MDCT (mean, 121.3 HU) were comparable with normal liver parenchyma on venous phase MDCT (117.3 HU) (p = 0.27). The threshold of 17.1 HU was the best threshold for the detection of pseudoenhancement in cysts (99% accuracy, 100% sensitivity, and 98% specificity). When this threshold was used instead of the conventional threshold of 10 HU, the mean necrosis proportion of treated HCC increased from 34.0% to 42.6% and the mean viable tumor proportion decreased from 66.0% to 57.4%. The quantification of viable HCC tissue based on 10 HU and the quantification of viable HCC tissue based on 17.1 HU were found to be significantly different (p < 0.0001).

CONCLUSION

The threshold of 17.1 HU may be the appropriate cutoff for nonenhancement in a necrotic HCC. Use of this threshold may potentially affect how response to therapy is quantified and categorized.

Role of yttrium-90 in the management of unresectable hepatocellular carcinoma and hepatic metastases

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is the sixth most common cancer and third leading cause of cancer-related death in the world. The management of unresectable HCC and hepatic metastases from various solid tumors is a clinical dilemma. There is paucity of data on the treatment of unresectable HCC and hepatic metastases with yttrium-90 (90Y) radioembolization.

METHODS

Thirty patients (mean age; 55.2 years; range 43-82 years) comprising 21 patients with HCC (12 patients have cirrhosis of which 3 patients belong to Child-Pugh class A and 9 patients belong to Child-Pugh class B), 7 patients with metastasis from colorectal cancer, 1 patient with metastasis from melanoma, and 1 patient with metastasis from ovarian carcinoma underwent resin-based 90Y radioembolization between 2013 and 2015 in our study. In all the patients, after embolization of non-target vasculature, SPECT and planar scintigraphy were done with the injection of 5-6 mCi (185-222 MBq) of 99mTc-labeled macroaggregated albumin (MAA) into the hepatic artery. Then, lung shunt fraction was assessed and dose was calculated based on body surface area (BSA) method for SIR-Spheres. Post therapeutic 90Y bremsstrahlung SPECT and 90Y PET was performed within 30 hours following therapy to see the hepatic and extrahepatic  distribution of spheres. Side effects following therapy were noted in all the patients. All patients were followed up with triphasic CT liver 3 months following therapy. Therapeutic response was evaluated with necrosis criteria used for therapy response assessment in solid tumors.

RESULTS

On follow up, 14 patients (46 %) developed minor side effects following treatment and resolved without active intervention. The most common side effects include mild abdominal pain in 11 patients (36 %), nausea in 8 patients (26 %), and fatigue in 6 patients (20 %). On follow up imaging at 3 months following treatment, a complete response was observed in two patients (7 %), partial response in seven patients (23 %), stable disease in 15 patients (50 %), and progressive disease in six patients (20 %).

CONCLUSION

This study provides supportive evidence of the safety and efficacy on 90Y radioembolization for the treatment of unresectable HCC and hepatic metastases from various solid tumors. 90Y PET is a better radionuclide technique for assessing the hepatic and extrahepatic distribution of spheres following therapy compared to 90Y Bremsstrahlung SPECT. Thus, 90Y radioembolization is proving to be promising treatment with average disease control rates around 80 % and should be widely utilized.

Transarterial Radioembolization with Yttrium-90 for the Treatment of Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is a common cause of worldwide mortality. Transarterial radioembolization (TARE) with yttrium-90 (Y90), a transcatheter intra-arterial procedure performed by interventional radiology, has become widely utilized in managing HCC.

Methods

The following is a focused review of TARE covering its commercially available products, clinical considerations of treatment, salient clinical trial data establishing its utility, and the current and future roles of TARE in the management of HCC.

Results

TARE is indicated for patients with unresectable, intermediate stage HCC. The two available products are glass and resin microspheres. All patients undergoing TARE must be assessed with a history, physical examination, clinical laboratory tests, imaging, and arteriography with macroaggregated albumin. TARE is safe and effective in the treatment of unresectable HCC, as it has a safer toxicity profile than chemoembolization, longer time-to-progression, greater ability to downsize and/or bridge patients to liver transplant, and utility in tumor complicated by portal vein thrombosis. TARE can also serve as an alternative to ablation and chemotherapy.

Conclusion

TARE assumes an integral role in the management of unresectable HCC and has been validated by numerous studies.

Hepatic imaging following intra-arterial embolotherapy

PURPOSE

To discuss guidelines and salient imaging findings of solid tumors treated with common intra-arterial procedures used in interventional oncology.

METHODS

A meticulous literature search of PubMed-indexed articles was conducted. Key words included "imaging + embolization," "imaging + TACE," "imaging + radioembolization," "imaging + Y90," "mRECIST," and "EASL." Representative post-treatment cross-sectional images were obtained from past cases in this institution.

RESULTS

Intra-arterial therapy (IAT) in interventional oncology includes bland embolization, chemoembolization, and radioembolization. Solid tumors of the liver are the primary focus of these procedures. Cross-sectional CT and/or MR are the main modalities used to image tumors after treatment. Traditional size-based response criteria (WHO and RECIST) alone are of limited utility in determining response to IAT; tumoral necrosis and enhancement must be considered. Specifically for HCC, the EASL and mRECIST guidelines are becoming widely adopted response criteria to assess these factors. DWI, FDG-PET, and CEUS are modalities that play an adjunctive but controversial role.

CONCLUSIONS

Radiologists must be aware that the different forms of intra-arterial therapy yield characteristic findings on cross-sectional imaging. Knowledge of these findings is integral to accurate assessment of tumor response and progression.

Hepatic imaging response to radioembolization with yttrium-90-labeled resin microspheres for tumor progression during systemic chemotherapy in patients with colorectal liver metastases

BACKGROUND

To assess response and the impact of imaging artifacts following radioembolization with yttrium-90-labeled resin microspheres ((90)Y-RE) based on the findings from a central independent review of patients with liver-dominant metastatic colorectal cancer (mCRC).

METHODS

Patients with mCRC who received (90)Y-RE (SIR-Spheres(®); Sirtex Medical, Sydney, Australia) at nine US institutions between July 2002 and December 2011 were included in the analysis. Tumor response was assessed at baseline and 3 months using either the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0 or 1.1. For each lesion, known artifacts affecting the interpretation of response (peri-tumoral edema and necrosis) were documented. Survivals (Kaplan-Meier analyses) were compared in responders [partial response (PR)] and non-responders [stable (SD) or progressive disease (PD)].

RESULTS

Overall, 195 patients (mean age 62 years) received (90)Y-RE after a median of 2 (range, 1-6) lines of prior chemotherapy. Using RECIST 1.0 and RECIST 1.1, 7.6% and 6.9% of patients were partial responders, 47.3% and 48.1% had SD, and 55.0% and 55.0% PD, respectively. RECIST 1.0 and RECIST 1.1 showed excellent agreement {Kappa =0.915 [95% confidence interval (CI): 0.856-0.975]}. Peri-tumoral edema was documented in 32.8%, necrosis in 48.1% and both in 57.3% of cases (using RECIST 1.0). Although baseline characteristics were similar in responders and non-responders (P>0.05), responders survived significantly longer in an analysis according to RECIST 1.0: PR median (95% CI) 25.2 (range, 9.2-49.4) months vs. SD 15.8 (range, 9.3-21.1) months vs. PD 7.1 (range, 6.0-9.5) months (P<0.0001).

CONCLUSIONS

RECIST 1.0 and RECIST 1.1 imaging responses provide equivalent interpretations in the assessment of hepatic tumors following (90)Y-RE. Radiologic lesion responses at 3 months must be interpreted with caution due to the significant proportion of patients with peri-tumoral edema and necrosis, which may lead to an under-estimation of PR/SD. Nevertheless, 3-month radiologic responses were predictive of prolonged survival.

Dramatic response to selective internal radiation therapy for unresectable hepatocellular carcinoma

A 54-year-old woman with a known history of multifocal hepatocellular carcinoma was treated with selective internal radiation therapy (SIRT) using yttrium-90 (⁹⁰Y) microspheres, despite disease relapses after surgical resection and transarterial chemoembolization. She developed a dramatic clinical, radiological and metabolic response after 9 weeks. This case provides visual illustration of the potential roles of SIRT in the treatment of hepatocellular carcinoma.

Magnetic resonance imaging of the liver after loco-regional and systemic therapy

Assessment of tumor response is crucial in determining the effectiveness of loco-regional and systemic therapy, and for determining the need for subsequent treatment. The ultimate goal is to improve patient's survival. Changes in tumor size and enhancement after therapy may not be detected early by the traditional response criteria. Tumor response is better assessed in the entire tumor volume rather than in a single axial plane. The purpose of this article is to familiarize the reader with early treatment response assessed by anatomic and volumetric functional magnetic resonance imaging metrics of the liver after loco-regional and systemic therapy.

Y90 radioembolization of colorectal cancer liver metastases: response assessment by contrast-enhanced computed tomography with or without PET-CT guidance

PURPOSE

To compare various computed tomography (CT) parameters to the positron emission tomography with computed tomography (PET-CT) response, with or without PET guidance for the response assessment of colorectal cancer (CRC) metastases treated by Y90 radioembolization.

METHODS

Thirty-six CRC metastases were retrospectively evaluated on 18F-Fluoro-Deoxy-Glucose PET-CT and contrast-enhanced computed tomography (CECT) performed at baseline and 2-3 months after Y90 radioembolization.

RESULTS

Median SUVmax values decreased from 11.39 to 6.71 after radioembolization (P<.001), and 23/36 (64%) metastases were categorized metabolic responses according to European Organisation for Research and Treatment of Cancer criteria. Only a decrease of the mean attenuation in the structural (P<.001) and metabolic active volume (P<.001) was observed. The change in these criteria was correlated with the change of SUVmax.

[18F]Fluorodeoxyglucose PET for Interventional Oncology in Liver Malignancy

[(18)F]Fluorodeoxyglucose (FDG) PET is a functional imaging tool that provides metabolic information, which has the potential to detect a lesion before it becomes anatomically apparent. This ability constitutes a strong argument for using FDG-PET/computed tomography (CT) in the management of oncology patients. Many studies have investigated the accuracy of FDG-PET or FDG-PET/CT for these purposes, but with small sample sizes based on retrospective cohorts. This article provides an overview of the role of FDG-PET or FDG-PET/CT in patients with liver malignancies treated by means of surgical resection, ablative therapy, chemoembolization, radioembolization, and brachytherapy, all being liver-directed oncologic interventions.

Radioembolization for colorectal cancer liver metastases: current role and future opportunities – the medical oncologist’s perspective

SUMMARY 

The liver is the most common and often the only site of metastatic disease in patients with metastatic colorectal cancer. For patients who do not have resectable disease, a number of liver-directed therapies are increasingly being used in routine clinical practice, including yttrium-90 radioembolization. The challenge for the medical oncologist is how best to integrate this promising new option into routine practice in the setting of ever-evolving standard systemic therapy options. Here we review the most recent data on the efficacy and safety of yttrium-90, considerations when selecting patients for treatment and we examine the potential impact of current clinical trials.

Tumor growth kinetics versus RECIST to assess response to locoregional therapy in breast cancer liver metastases

RATIONALE AND OBJECTIVES

The aim of our study was to evaluate changes in growth kinetics of breast cancer liver metastasis in response to locoregional therapy and compare them to Response Evaluation Criteria in Solid Tumors (RECIST).

MATERIALS AND METHODS

This Health Insurance Portability and Accountability Act-compliant retrospective study was Institutional Review Board approved. Thirty-four chemorefractory breast cancer liver metastases from 21 patients treated with yttrium-90 ((90)Y) were evaluated. Pre- and posttreatment computed tomography (CT) scans were used to calculate tumor growth kinetics. The growth parameter analyzed was reciprocal of doubling time (RDT). RDT range for stable disease (SD) was defined by the measurement error rate. A negative RDT below the SD range defined response and was categorized as either partial response (PR) or complete response, whereas a positive RDT value above the SD range indicated progressive disease (PD). Comparison was made to tumor response classification according to percentage change in the lesion's maximal diameter per RECIST. Lin's concordance correlation coefficient, Bland-Altman plot, Wilcoxon signed rank test, and Student t test were used for analysis. Significance was set at 0.05.

RESULTS

RDT range for SD ranged from -0.46 to +2.17. Six lesions with PR based on RECIST showed PR based on their volumetric growth rate (mean RDT of -17.3 ± 2.6). Similarly, one lesion with PD according to RECIST was categorized as PD based on its growth kinetics (RDT of 10.2). However, 14 (51.85%) lesions classified as SD by RECIST had PR according to growth kinetics (mean RDT of -7.8), six (22.22%) lesions were categorized as SD (mean RDT of 0.8), whereas seven (25.93%) lesions showed PD (mean RDT of 4.5). Growth kinetic parameters were significantly different for lesions with PR when compared to lesions with PD (P < .0001).

CONCLUSIONS

In patients with breast cancer liver metastases undergoing locoregional therapy, RECIST categorization may not be an accurate reflection of treatment response.

Imaging tumor response following liver-directed intra-arterial therapy

Liver-directed intra-arterial therapies are palliative treatment options for patients with unresectable liver cancer; their use has also resulted in patients being downstaged leading to curative resection and transplantation. These intra-arterial therapies include transarterial embolization, conventional transarterial chemoembolization (TACE), drug-eluting bead TACE and radioembolization. Assessment of imaging response following these liver-directed intra-arterial therapies is challenging but pivotal for patient management. Size measurements based on computed tomography or magnetic resonance imaging (MRI) have been traditionally used to assess tumor response to therapy. However, these anatomic changes lag behind functional changes and may require months to occur. Further, these intra-arterial therapies cause acute tumor necrosis, which may result in a paradoxical increase in tumor size on early follow-up imaging despite complete cell death or necrosis. This concept is unique comparing to changes seen following systemic chemotherapy. The recent development of functional imaging techniques including diffusion-weighted MRI (DW MRI) and positron emission tomography (PET) allow for early assessment of treatment response and even prediction of overall tumor response to intra-arterial therapies. Although the results of DW MRI and PET studies are promising, the impact of these imaging modalities to assess treatment response has been limited without standardized protocols. The aim of this review article is to delineate the best practice for assessing tumor response in patients with primary or secondary hepatic malignancies undergoing intra-arterial therapies.

Yttrium-90 radioembolization of malignant tumors of the liver: gallbladder effects

OBJECTIVE

After (90)Y-microsphere radioembolization for unresectable hepatic neoplasms, the nearby gallbladder is susceptible to radiation-induced cholecystitis, an uncommon complication. The purpose of this study was to characterize the imaging findings after (90)Y radioembolization of the gallbladder and to assess the incidence of clinically significant radiation-induced cholecystitis.

MATERIALS AND METHODS

Medical records were retrospectively reviewed for cholecystectomy after (90)Y treatment of 133 consecutively registered patients (76 men, 57 women; average age, 65 years). Thirty-four of the patients had primary and 99 had secondary liver neoplasms. The pretreatment and posttreatment cross-sectional images of 85 of the patients were available for review.

RESULTS

Clinically significant radiation-induced cholecystitis occurred in 1 of the 133 patients (0.8%). After radioembolization, gallbladder imaging abnormalities were found in 84 of 85 patients (99%), but none was associated with clinically significant radiation-induced cholecystitis.

CONCLUSION

The incidence of clinically significant radiation-induced cholecystitis was only 0.8% despite a high prevalence of gallbladder imaging abnormalities after (90)Y radioembolization. Therefore, in the postinterventional care of patients with abdominal pain after (90)Y radioembolization, even if imaging abnormalities of the gallbladder are identified, cholecystectomy should be reserved for patients in whom other causes of pain have been excluded.

Early arterial stasis during resin-based yttrium-90 radioembolization: incidence and preliminary outcomes

OBJECTIVES

This study was conducted to determine the incidence of early stasis in radioembolization using resin yttrium-90 (Y-90) microspheres, to evaluate potential contributing factors, and to review initial imaging outcomes.

METHODS

Patients in whom early stasis occurred were compared with those in whom complete delivery was achieved for tumour type and vascularity, tumour : normal liver ratio (T : N ratio) at technetium-99m-macroaggregated albumin (Tc-99m-MAA) angiography, previous intra-arterial therapy, and infusion site (left, right or whole liver). Tumour response was evaluated at 3 months and defined according to whether a partial response and stable disease versus progressive disease were demonstrated.

RESULTS

A total of 71 patients underwent 128 Y-90 infusions in which 26 (20.3%) stasis events occurred. Hypervascular and hypovascular tumours had similar rates of stasis (17.4% versus 27.8%; P = NS). The mean ± standard deviation T : N ratio was 3.03 ± 1.54 and 3.66 ± 2.79 in patients with and without stasis, respectively (P = NS). Stasis occurred in 14 of 81 (17.3%) and 12 of 47 (25.5%) infusions following previous intra-arterial therapy and in therapy-naïve territories, respectively (P = NS). Early stasis occurred in 15 of 41 (36.6%) left, 10 of 65 (15.4%) right and one of 22 (4.5%) whole liver infusions (P < 0.001). Rates of partial response and stable disease were similar in the stasis (88.3%) and non-stasis (76.0%) groups (P = NS).

CONCLUSIONS

Early stasis occurred in approximately 20% of infusions with similar incidences in hyper- and hypovascular tumours. Whole-liver therapy reduced the incidence of stasis. Stasis did not appear to affect initial imaging outcomes.

Early treatment response evaluation after yttrium-90 radioembolization of liver malignancy with CT perfusion

PURPOSE

To evaluate computed tomography (CT) perfusion for assessment of early treatment response after transarterial radioembolization of patients with liver malignancy.

MATERIALS AND METHODS

Dynamic contrast-enhanced CT liver perfusion was performed before and 4 weeks after transarterial radioembolization in 40 patients (25 men and 15 women; mean age, 64 y ± 11; range, 35-80 y) with liver metastases (n = 27) or hepatocellular carcinoma (HCC) (n = 13). Arterial perfusion (AP) of tumors derived from CT perfusion and tumor diameters were measured on CT perfusion before and after transarterial radioembolization. Success of transarterial radioembolization was evaluated on morphologic follow-up imaging (median follow-up time, 4 mo) based on Response Evaluation Criteria in Solid Tumors (Version 1.1). CT perfusion parameters before and after transarterial radioembolization for different response groups were compared. Kaplan-Meier curves were plotted to illustrate overall 1-year survival rates.

RESULTS

Liver metastases showed significant differences in AP before and after transarterial radioembolization in responders (P < .05) but not in nonresponders (P = .164). In HCC, AP values before and after transarterial radioembolization were not significantly different in responders and nonresponders (P = .180 and P = .052). Tumor diameters were not significantly different on CT perfusion before and after transarterial radioembolization in responders and nonresponders with liver metastases and HCC (P = .654, P = .968, P = .148, P = .164). In patients with significant decrease of AP in liver metastases after transarterial radioembolization, 1-year overall survival was significantly higher than in patients showing no reduction of AP.

CONCLUSIONS

CT perfusion showed early reduction of AP in liver metastases responding to transarterial radioembolization; tumor diameter remained unchanged early after treatment. No significant early treatment response to transarterial radioembolization was found in patients with HCC. In patients with liver metastases, a decrease of AP after transarterial radioembolization was associated with a higher 1-year overall survival rate.

The role of 18F-FDG-PET and PET/CT in patients with colorectal liver metastases undergoing selective internal radiation therapy with yttrium-90: a first evidence-based review

PURPOSE

To provide a first evidence-based review of the literature on the role of fluorine-18-fluorodeoxyglucose positron emission tomography and positron emission tomography/computed tomography (FDG-PET and PET/CT) in patients with colorectal liver metastases (CRLM) undergoing selective internal radiation therapy (SIRT) with yttrium-90 ((90)Y) microspheres.

METHODS

A comprehensive computer literature search was conducted to find relevant published articles on whole-body FDG-PET or PET/CT in patients with CRLM undergoing SIRT.

RESULTS

We identified 19 studies including 833 patients with CRLM undergoing SIRT. The role of FDG-PET or PET/CT was analysed in treatment planning, treatment response evaluation, and as prognostic tool.

CONCLUSION

FDG-PET and PET/CT provide additional information in treatment evaluation of CRLM patients treated with SIRT and may have a role in treatment planning and patient selection. FDG-PET/CT is emerging as good prognostic tool in these patients.

Towards new response criteria in neuroendocrine tumors: which changes in MRI parameters are associated with longer progression-free survival after radioembolization of liver metastases?

PURPOSE

To evaluate the association of therapy-related changes in imaging parameters with progression-free survival (PFS) of patients with unresectable liver metastases from neuroendocrine tumors (NETLMs).

MATERIALS AND METHODS

Forty-five radioembolized patients (median age: 62 years; range: 43-75) received a pre- and 3 months posttherapeutic magnetic resonance imaging (MRI) examination. The latter were evaluated for tumor size, arterial enhancement, and necrosis pattern. Influences of therapy-related changes on PFS were analyzed. Statistical analysis included Student's t-test, Wilcoxon test, Cox regression analysis, and Kaplan-Meier curves.

RESULTS

The median percentage decrease in sum of diameters was 9.7% (range: 43.9% decrease to 15.4% increase). Twenty-one patients (47%) showed increased necrosis. Three parameters were associated with significantly longer PFS: a decrease of diameter (hazard ratio [HR]: 0.206; 95% confidence interval [CI]: 0.058-0.725; P = 0.0139), a decrease in tumor arterial enhancement (HR: 0.143; 95% CI: 0.029-0.696; P = 0.0160), and an increase in necrosis after 3 months (HR: 0.321; 95% CI: 0.104-0.990; P = 0.0480). Multivariate analysis revealed that changes in diameter and arterial enhancement have complementary information and are associated independently with long PFS.

CONCLUSION

A decrease both in sum of diameters and arterial enhancement of metastases, as well as an increase in necrosis, are associated with significantly longer PFS after radioembolization.

Yttrium-90 radioembolization of liver tumors: what do the images tell us?

Transarterial radioembolization (TARE) with yttrium 90 microspheres is an increasingly popular therapy for both primary and secondary liver malignancies. TARE entails delivery of β-particle brachytherapy and embolization of the tumor vasculature. The consequent biological sequelae are distinct from those of other transarterial therapies for liver tumors, as reflected in the often baffling post-treatment imaging features. As the clinical use of TARE is increasing, more diverse post-treatment radiological findings are encountered with variable overlap among treatment response, residual disease, reactionary changes and complications. Thus, post-TARE image interpretation is challenging. This review provides a comprehensive description of the different findings seen in post-treatment scans, with the aim of facilitating appropriate radiological interpretation of post-TARE pathologic changes, notwithstanding their existing limitations.

Functional imaging biomarkers for assessing response to treatment in liver and lung metastases

Management of patients with metastatic cancer and development of new treatments rely on imaging to provide non-invasive biomarkers of tumour response and progression. The widely used size-based criteria have increasingly become inadequate where early measures of response are required to avoid toxicity of ineffective treatments, as biological, physiologic, and molecular modifications in tumours occur before changes in gross tumour size. A multiparametric approach with the current range of imaging techniques allows functional aspects of tumours to be simultaneously interrogated. Appropriate use of these imaging techniques and their timing in relation to the treatment schedule, particularly in the context of clinical trials, is fundamental. There is a lack of consensus regarding which imaging parameters are most informative for a particular disease site and the best time to image so that, despite an increasing body of literature, open questions on these aspects remain. In addition, standardization of these new parameters is required. This review summarizes the published literature over the last decade on functional and molecular imaging techniques in assessing treatment response in liver and lung metastases.

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.

Review of the impact of antineoplastic therapies on the risk for cholelithiasis and acute cholecystitis

BACKGROUND

Development of cholecystitis in patients with malignancies can potentially disrupt their treatment and alter prognosis. This review aims to identify antineoplastic interventions associated with increased risk of cholecystitis in cancer patients.

METHODS

A comprehensive search strategy was developed to identify articles pertaining to risk factors and complications of cholecystitis in cancer patients. FDA-issued labels of novel antineoplastic drugs released after 2010 were hand-searched to identify more therapies associated with cholecystitis in nonpublished studies.

RESULTS

Of an initial 2,932 articles, 124 were reviewed in the study. Postgastrectomy patients have a high (5-30 %) incidence of gallstone disease, and 1-7 % develop symptomatic disease. One randomized trial addressing the role of cholecystectomy concurrent with gastrectomy is currently underway. Among other risk groups, patients with neuroendocrine tumors treated with somatostatin analogs have a 15 % risk of cholelithiasis, and most are symptomatic. Hepatic artery based therapies carry a risk of cholecystitis (0.02-24 %), although the risk is reduced with selective catheterization. Myelosuppression related to chemotherapeutic agents (0.4 %), bone marrow transplantation, and treatment with novel multikinase inhibitors are associated with high risk of cholecystitis.

CONCLUSIONS

There are several risk factors for gallbladder-related surgical emergencies in patients with advanced malignancies. Incidental cholecystectomy at index operation should be considered in patients planned for gastrectomy, and candidates for regional therapies to the liver or somatostatin analogs. While prophylactic cholecystectomy is currently recommended for patients with cholelithiasis receiving myeloablative therapy, this strategy may have value in patients treated with multikinase inhibitors, immunotherapy, and oncolytic viral therapy based on evolving evidence.

A radiologist's guide to treatment response criteria in oncologic imaging: anatomic imaging biomarkers

OBJECTIVE

The purpose of this article is to describe the imaging biomarkers of treatment response and provide an overview of anatomic imaging biomarkers.

CONCLUSION

Imaging biomarkers of treatment response have evolved into the primary endpoint of response in most phase 2 studies. Anatomic imaging biomarkers are applied to depict change in tumor size in response to treatment and are currently the most commonly applied method of treatment response evaluation.