Preoperative 18[F]-fluorodeoxyglucose positron emission tomography standardized uptake values predict survival after esophageal adenocarcinoma resection

Association of dynamic contrast-enhanced MRI and 18F-Fluorodeoxyglucose PET/CT parameters with neoadjuvant therapy response and survival in esophagogastric cancer

INTRODUCTION

Better predictive markers are needed to deliver individualized care for patients with primary esophagogastric cancer. This exploratory study aimed to assess whether pre-treatment imaging parameters from dynamic contrast-enhanced MRI and 18F-fluorodeoxyglucose (18F-FDG) PET/CT are associated with response to neoadjuvant therapy or outcome.

MATERIALS AND METHODS

Following ethical approval and informed consent, prospective participants underwent dynamic contrast-enhanced MRI and 18F-FDG PET/CT prior to neoadjuvant chemotherapy/chemoradiotherapy ± surgery. Vascular dynamic contrast-enhanced MRI and metabolic 18F-FDG PET parameters were compared by tumor characteristics using Mann Whitney U test and with pathological response (Mandard tumor regression grade), recurrence-free and overall survival using logistic regression modelling, adjusting for predefined clinical variables.

RESULTS

39 of 47 recruited participants (30 males; median age 65 years, IQR: 54, 72 years) were included in the final analysis. The tumor vascular-metabolic ratio was higher in patients remaining node positive following neoadjuvant therapy (median tumor peak enhancement/SUVmax ratio: 0.052 vs. 0.023, p = 0.02). In multivariable analysis adjusted for age, gender, pre-treatment tumor and nodal stage, peak enhancement (highest gadolinium concentration value prior to contrast washout) was associated with pathological tumor regression grade. The odds of response decreased by 5% for each 0.01 unit increase (OR 0.95; 95% CI: 0.90, 1.00, p = 0.04). No 18F-FDG PET/CT parameters were predictive of pathological tumor response. No relationships between pre-treatment imaging and survival were identified.

CONCLUSION

Pre-treatment esophagogastric tumor vascular and metabolic parameters may provide additional information in assessing response to neoadjuvant therapy.

Prognostic value of baseline 18F-FDG PET/CT in patients with esophageal squamous cell carcinoma treated with definitive (chemo)radiotherapy

PURPOSE

To investigate the prognostic value of baseline ¹⁸F-FDG PET/CT in patients with esophageal squamous cell carcinoma (ESCC) treated with definitive (chemo)radiotherapy.

METHODS

A total of 98 ESCC patients with cTNM stage T1-4, N1-3, M0 who received definitive (chemo)radiotherapy after ¹⁸F-FDG PET/CT examination from December 2013 to December 2020 were retrospectively analyzed. Clinical factors included age, sex, histologic differentiation grade, tumor location, clinical stage, and treatment strategies. Parameters obtained by ¹⁸F-FDG PET/CT included SUV_max of primary tumor (SUV_Tumor), metabolic tumor volume (MTV), total lesion glycolysis (TLG), SUV_max of lymph node (SUV_LN), PET positive lymph nodes (PLNS) number, the shortest distance between the farthest PET positive lymph node and the primary tumor in three-dimensional space after the standardization of the patient BSA (SD_max(LN-T)). Univariate and multivariate analysis was conducted by Cox proportional hazard model to explore the significant factors affecting overall survival (OS) and progression-free survival (PFS) in ESCC patients.

RESULTS

Univariate analysis showed that tumor location, SUV_Tumor, MTV, TLG, PLNS number, SD_{max (LN-T)} were significant predictors of OS and tumor location, and clinical T stage, SUV_Tumor, MTV, TLG, SD_{max (LN-T)} were significant predictors of PFS (all p < 0.1). Multivariate analysis showed that MTV and SD_{max (LN-T)} were independent prognostic factors for OS (HR = 1.018, 95% CI 1.006-1.031; p = 0.005; HR = 6.988, 95% CI 2.119-23.042; p = 0.001) and PFS (HR = 1.019, 95% CI 1.005-1.034; p = 0.009; HR = 5.819, 95% CI 1.921-17.628; p = 0.002). Combined with independent prognostic factors MTV and SD_{max (LN-T)}, we can further stratify patient risk.

CONCLUSIONS

Before treatment, ¹⁸F-FDG PET/CT has important prognostic value for patients with ESCC treated with definitive (chemo)radiotherapy. The lower the value of MTV and SD_{max (LN-T)}, the better the prognosis of patients.

Can 18F-FDG PET/CT Radiomics Features Predict Clinical Outcomes in Patients with Locally Advanced Esophageal Squamous Cell Carcinoma?

Simple Summary

PET/CT is an important staging modality in the baseline assessment of locally advanced esophageal squamous cell carcinoma. Accurate staging and response prediction in these patients is essential for management. The aim of this retrospective study was to assess the usefulness of ¹⁸F-FDG PET/CT radiomics features in predicting outcomes such as tumor and nodal categories, PET-based response to induction chemotherapy, progression-free survival, and overall survival. In a final cohort of 74 patients, we found that the developed radiomics models can predict these clinical and prognostic outcomes with reasonable accuracy, similar or better than those derived from conventional imaging. Future studies with a larger cohort would be helpful in establishing the significance of these models.

Abstract

This study aimed to assess the usefulness of radiomics features of ¹⁸F-FDG PET/CT in patients with locally advanced esophageal cancers (ESCC) in predicting outcomes such as clinical tumor (cT) and nodal (cN) categories, PET response to induction chemotherapy (PET response), progression-free survival (PFS), and overall survival (OS). Pretreatment PET/CT images from patients who underwent concurrent chemoradiotherapy from July 2002 to February 2017 were segmented, and data were split into training and test sets. Model development was performed on the training datasets and a maximum of five features were selected. Final diagnostic accuracies were determined using the test dataset. A total of 86 PET/CTs (58 men and 28 women, mean age 65 years) were segmented. Due to small lesion size, 12 patients were excluded. The diagnostic accuracies as derived from the CT, PET, and combined PET/CT test datasets were as follows: cT category—70.4%, 70.4%, and 81.5%, respectively; cN category—69.0%, 86.2%, and 86.2%, respectively; PET response—60.0%, 66.7%, and 70.0%, respectively; PFS—60.7%, 75.0%, and 75.0%, respectively; and OS—51.7%, 55.2%, and 62.1%, respectively. A radiomics assessment of locally advanced ESCC has the potential to predict various clinical outcomes. External validation of these models would be further helpful.

Can 18F-FDG PET/CT Radiomics Features Predict Clinical Outcomes in Patients with Locally Advanced Esophageal Squamous Cell Carcinoma?

This study aimed to assess the usefulness of radiomics features of ¹⁸F-FDG PET/CT in patients with locally advanced esophageal cancers (ESCC) in predicting outcomes such as clinical tumor (cT) and nodal (cN) categories, PET response to induction chemotherapy (PET response), progression-free survival (PFS), and overall survival (OS). Pretreatment PET/CT images from patients who underwent concurrent chemoradiotherapy from July 2002 to February 2017 were segmented, and data were split into training and test sets. Model development was performed on the training datasets and a maximum of five features were selected. Final diagnostic accuracies were determined using the test dataset. A total of 86 PET/CTs (58 men and 28 women, mean age 65 years) were segmented. Due to small lesion size, 12 patients were excluded. The diagnostic accuracies as derived from the CT, PET, and combined PET/CT test datasets were as follows: cT category-70.4%, 70.4%, and 81.5%, respectively; cN category-69.0%, 86.2%, and 86.2%, respectively; PET response-60.0%, 66.7%, and 70.0%, respectively; PFS-60.7%, 75.0%, and 75.0%, respectively; and OS-51.7%, 55.2%, and 62.1%, respectively. A radiomics assessment of locally advanced ESCC has the potential to predict various clinical outcomes. External validation of these models would be further helpful.

Diagnostic accuracy of SUVmax in predicting malignancy of supraclavicular lymph nodes from primary oesophageal cancer

PURPOSE

To determine the diagnostic accuracy and optimum cut-off value of SUVmax on PET to predict malignancy of supraclavicular lymph nodes (SCLNs) in patients with oesophageal carcinoma.

MATERIAL AND METHODS

All diagnosed cases of oesophageal cancer were retrospectively reviewed (2010-2016). Patients that had a confirmed diagnosis of oesophageal cancer with avid SCLNs on staging PET were included in the study. 33 SCLNs that subsequently underwent ultrasound guided biopsy for staging were analysed. The maximum uptake values (SUVmax) of the SCLNs and primary tumours were measured. A receiver operating characteristic (ROC) analysis was performed to determine the optimum cut off of SUVmax in predicting malignancy.

RESULTS

24/33 PET-detected SCLNs were malignant. ROC analysis identified the best nodal SUVmax cut-off to be 3.0. The diagnostic accuracy of PET was 76.0 % (sensitivity = 78.9 %, specificity = 66.6 %). For SCLNs with SUVmax > 3.0, PET showed a positive predictor value of 88.2 %; for SCLNs < 3.0, PET showed a negative predictor value of 50 %. The median SUVmax of pathologically negative and positive nodes were 2.8 (range 1.8-6.0) and 5.3 (range 1.9-13.4). The median primary tumour SUVmax was 13.8 (range 3.7-30.0). The SUVmax of metastatic lymph nodes were significant higher than those of benign lesions (p < 0.05).

CONCLUSION

Our study revealed an accuracy rate of 76 % for PET detected SCLNs in patients with oesophageal carcinoma. For SCLNs with SUVmax > 3.0, PET had a high PPV (88 %), which can minimize the need for further diagnostic tests.

ePAD: An Image Annotation and Analysis Platform for Quantitative Imaging

Medical imaging is critical for assessing the response of patients to new cancer therapies. Quantitative lesion assessment on images is time-consuming, and adopting new promising quantitative imaging biomarkers of response in clinical trials is challenging. The electronic Physician Annotation Device (ePAD) is a freely available web-based zero-footprint software application for viewing, annotation, and quantitative analysis of radiology images designed to meet the challenges of quantitative evaluation of cancer lesions. For imaging researchers, ePAD calculates a variety of quantitative imaging biomarkers that they can analyze and compare in ePAD to identify potential candidates as surrogate endpoints in clinical trials. For clinicians, ePAD provides clinical decision support tools for evaluating cancer response through reports summarizing changes in tumor burden based on different imaging biomarkers. As a workflow management and study oversight tool, ePAD lets clinical trial project administrators create worklists for users and oversee the progress of annotations created by research groups. To support interoperability of image annotations, ePAD writes all image annotations and results of quantitative imaging analyses in standardized file formats, and it supports migration of annotations from various propriety formats. ePAD also provides a plugin architecture supporting MATLAB server-side modules in addition to client-side plugins, permitting the community to extend the ePAD platform in various ways for new cancer use cases. We present an overview of ePAD as a platform for medical image annotation and quantitative analysis. We also discuss use cases and collaborations with different groups in the Quantitative Imaging Network and future directions.

18F- FDG PET/CT-derived parameters predict clinical stage and prognosis of esophageal cancer

BACKGROUND

Although ¹⁸F- FDG PET/CT is validated in baseline workup of esophageal cancer to detect distant metastases, it remains underused in assessing local staging and biology of the primary tumor. This study aimed to evaluate the association between ¹⁸F- FDG PET/CT-derived parameters of esophageal cancer, and its clinico-pathological features and prognosis.

METHODS

All patients (n = 86) with esophageal adenocarcinoma or squamous cell cancer operated between 2005 and 2014 were analyzed. Linear regression was used to identify clinico-pathologic features of esophageal cancer associated with the tumor's maximal Standardized Uptake Value (SUV_max), Total Lesion Glycolysis (TLG) and Metabolic Tumor Volume (MTV). ROC curve analysis was performed to precise the optimal cutoff of each variable associated with a locally advanced (cT3/4) status, long-term survival and recurrence. Kaplan Meier curves and Cox regression were used for survival analyses.

RESULTS

High baseline SUV_max was associated with cT3/4 status and middle-third tumor location, TLG with a cT3/4 and cN+ status, whereas MTV only with active smoking. A cT3/4 status was significantly predicted by a SUV_max > 8.25 g/mL (p < 0.001), TLG > 41.7 (p < 0.001) and MTV > 10.70 cm³ (p < 0.01) whereas a SUV_max > 12.7 g/mL was associated with an early tumor recurrence and a poor disease-free survival (median 13 versus 56 months, p = 0.030), particularly in squamous cell cancer.

CONCLUSIONS

Baseline ¹⁸F- FDG PET/CT has a high predictive value of preoperative cT stage, as its parameters SUV_max, TLG and MTV can predict a locally advanced tumor with high accuracy. A SUV_max > 12.7 g/mL may herald early tumor recurrence and poor disease-free survival.

Imaging biomarkers for the treatment of esophageal cancer

Esophageal cancer is known as one of the malignant cancers with poor prognosis. To improve the outcome, combined multimodality treatment is attempted. On the other hand, advances in genomics and other “omic” technologies are paving way to the patient-oriented treatment called “personalized” or “precision” medicine. Recent advancements of imaging techniques such as functional imaging make it possible to use imaging features as biomarker for diagnosis, treatment response, and prognosis in cancer treatment. In this review, we will discuss how we can use imaging derived tumor features as biomarker for the treatment of esophageal cancer.

The Warburg effect: persistence of stem-cell metabolism in cancers as a failure of differentiation

Background

Two recent observations regarding the Warburg effect are that (i) the metabolism of stem cells is constitutive (aerobic) glycolysis while normal cellular differentiation involves a transition to oxidative phosphorylation and (ii) the degree of glucose uptake of a malignancy as imaged by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is associated with histologic measures of tumor differentiation. Combining these observations, we hypothesized that the high levels of glucose uptake observed in poorly differentiated cancers may reflect persistence of the glycolytic metabolism of stem cells in malignant cells that fail to fully differentiate.

Patients and methods

Tumor glucose uptake was measured by FDG-PET in 552 patients with histologically diverse cancers. We used normal mixture modeling to explore FDG-PET standardized uptake value (SUV) distributions and tested for associations between glucose uptake and histological differentiation, risk of lymph node metastasis, and survival. Using RNA-seq data, we carried out pathway and transcription factor analyses to compare tumors with high and low levels of glucose uptake.

Results

We found that well-differentiated tumors had low FDG uptake, while moderately and poorly differentiated tumors had higher uptake. The distribution of SUV for each histology was bimodal, with a low peak around SUV 2-5 and a high peak at SUV 8-14. The cancers in the two modes were clinically distinct in terms of the risk of nodal metastases and death. Carbohydrate metabolism and the pentose-related pathway were elevated in the poorly differentiated/high SUV clusters. Embryonic stem cell-related signatures were activated in poorly differentiated/high SUV clusters.

Conclusions

Our findings support the hypothesis that the biological basis for the Warburg effect is a persistence of stem cell metabolism (i.e. aerobic glycolysis) in cancers as a failure to transition from glycolysis-utilizing undifferentiated cells to oxidative phosphorylation-utilizing differentiated cells. We found that cancers cluster along the differentiation pathway into two groups, utilizing either glycolysis or oxidative phosphorylation. Our results have implications for multiple areas of clinical oncology.

Positron-Emission Tomography Scan-Directed Chemoradiation for Esophageal Squamous Cell Carcinoma: No Benefit for a Change in Chemotherapy in Positron-Emission Tomography Nonresponders

INTRODUCTION

Preoperative or definitive chemoradiation is an accepted treatment for locally advanced esophageal squamous cell carcinoma (ESCC). The MUNICON study showed that positron-emission tomography (PET) response following induction chemotherapy was predictive of outcomes in patients with gastroesophageal junction adenocarcinoma. We evaluated the predictive value of PET following induction chemotherapy in ESCC patients and assessed the impact of changing chemotherapy during radiation in PET nonresponders.

METHODS

We retrospectively reviewed all patients with locally advanced ESCC who received induction chemotherapy and chemoradiation; all patients had a PET before and after induction chemotherapy. Survival was calculated from date of repeat PET using Kaplan-Meier analysis and compared between groups using the log-rank test.

RESULTS

Of 111 patients, 70 (63%) were PET responders (defined as a 35% or more decrease in maximum standard uptake value) to induction chemotherapy. PET responders received the same chemotherapy during radiation. Of 41 PET nonresponders, 16 continued with the same chemotherapy and 25 were changed to alternative chemotherapy with radiation. Median progression-free survival (70.1 months versus 7.1 months, p < 0.01) and overall survival (84.8 months versus 17.2 months, p < 0.01) were improved for PET responders versus nonresponders. Median progression-free survival and overall survival for PET nonresponders who changed chemotherapy versus those who did not were 6.4 months versus 8.3 months (p = 0.556) and 14.1 versus 17.2 months (p = 0.81), respectively.

CONCLUSIONS

PET after induction chemotherapy highly predicts for outcomes in ESCC patients who receive chemoradiation. However, our results suggest that PET nonresponders do not benefit from changing chemotherapy during radiation. Future trials should use PET nonresponse after induction chemotherapy to identify poor prognosis patients for novel therapies.

Can the Efficacy of [18F]FDG-PET/CT in Clinical Oncology Be Enhanced by Screening Biomolecular Profiles?

Positron Emission Tomography (PET) is a functional imaging modality widely used in clinical oncology. Over the years the sensitivity and specificity of PET has improved with the advent of specific radiotracers, increased technical accuracy of PET scanners and incremental experience of Radiologists. However, significant limitations exist—most notably false positives and false negatives. Additionally, the accuracy of PET varies between cancer types and in some cancers, is no longer considered a standard imaging modality. This review considers the relative influence of macroscopic tumour features such as size and morphology on 2-Deoxy-2-[¹⁸F]fluoroglucose ([¹⁸F]FDG) uptake by tumours which, though well described in the literature, lacks a comprehensive assessment of biomolecular features which may influence [¹⁸F]FDG uptake. The review aims to discuss the potential influence of individual molecular markers of glucose transport, glycolysis, hypoxia and angiogenesis in addition to the relationships between these key cellular processes and their influence on [¹⁸F]FDG uptake. Finally, the potential role for biomolecular profiling of individual tumours to predict positivity on PET imaging is discussed to enhance accuracy and clinical utility.

Clinical significance of SUVmax on preoperative 18F-fluorodeoxyglucose positron emission tomography in patients who underwent R0-esophagectomy for esophageal cancer

The standardized uptake value (SUV) is a marker of tumor glucose metabolism, detected using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and may reflect tumor aggressiveness. The purpose of this study was to evaluate the clinical significance of maximum SUV (SUVmax) of primary esophageal cancer (EC) lesions. A total of 86 patients with EC who underwent pre-treatment FDG-PET and R0-resection were included in our study. The mean patient age was 65 years, and 87% were men. Histologically, cancers included squamous cell carcinomas, adenocarcinomas, and other tumors in 72, 3, and 11 patients, respectively. Preoperative chemotherapy with or without radiotherapy was performed in 4 and 37 patients, respectively. Measured patient outcomes included the correlation between the SUVmax of the primary EC lesion and clinicopathological factors in patients who did not undergo preoperative treatment (n = 45), and the investigation of relapse-free survival (RFS) according to SUVmax and the relationship between SUVmax and recurrence sites in all patients (n=86). The mean SUVmax was 8.9 ± 4.6, and SUVmax values significantly correlated with tumor invasion depth and stage. The 5-year RFS for the enrolled patients was 57%, and the RFS of patients with SUVmax < 7.0 was better than that of patients with SUVmax ≥ 7.0, with a marginal difference (p = 0.0892). Lymph node recurrences were significantly more common in patients with SUVmax ≥ 7.0, compared to patients with SUVmax < 7.0. Therefore, the SUVmax value of the primary EC lesion before preoperative treatment may be predictive of RFS and lymph node recurrence.

PET/Computed Tomography Scanning and Precision Medicine: Esophageal Cancer

Esophageal cancer commonly has a poor prognosis, which requires an accurate diagnosis and early treatment to improve outcome. Other modalities for staging, such as endoscopic ultrasound imaging and computed tomography (CT) scans, have a role in diagnosis and staging. However, PET with fluorine-18 fluoro-2-deoxy-d-glucose/CT (FDG PET/CT) scanning allows for improved detection of distant metastatic disease and can help to prevent unnecessary interventions that would increase morbidity. FDG PET/CT scanning is valuable in the neoadjuvant chemotherapy assessment and predicting survival outcomes subsequent to surgery. FDG PET/CT scanning detects recurrent disease and metastases in follow-up.

Does Metastatic Lymph Node SUVmax Predict Survival in Patients with Esophageal Cancer?

Objective:

We aimed to investigate the SUVmax of primary tumor and metastatic lymph node in predicting survival in patients with esophageal cancer.

Methods:

We retrospectively analyzed patients with esophageal cancer between 2009 and 2011 who had FDG positron-emission tomography (PET)/computed tomography (CT). All patients were followed-up to 2013. Clinical staging, SUVmax of primary tumor and metastatic lymph node were evaluated.

Results:

One hundred seven patients were included in the study. All patients were followed-up between 2 and 49 months. The mean SUVmax of primary tumor and metastatic lymph node were 19.3±8.8 and 10.4±9.1, respectively. Metastatic lymph node SUVmax had an effect in predicting survival whereas primary tumor SUVmax did not have an effect (p=0.014 and p=0.262, respectively). Multivariate Cox regression analysis showed that clinical stage of the disease was the only independent factor predicting survival (p=0.001).

Conclusion:

Among patients with esophageal cancer, the value of primary tumor SUVmax did not have an effect on survival. Clinical stage assessed with FDG PET/CT imaging was found to predict survival in esophageal carcinoma. Additionally, lymph node SUVmax was identified as a new parameter in predicting survival in the present study.

The 100 most cited articles investigating the radiological staging of oesophageal and junctional cancer: a bibliometric analysis

Objectives

Accurate staging of oesophageal cancer (OC) is vital. Bibliometric analysis highlights key topics and publications that have shaped understanding of a subject. The 100 most cited articles investigating radiological staging of OC are identified.

Methods

The Thomas Reuters Web of Science database with search terms including “CT, PET, EUS, oesophageal and gastro-oesophageal junction cancer” was used to identify all English language, full-script articles. The 100 most cited articles were further analysed by topic, journal, author, year and institution.

Results

A total of 5,500 eligible papers were returned. The most cited paper was Flamen et al. (n = 306), investigating the utility of positron emission tomography (PET) for the staging of patients with potentially operable OC. The most common research topic was accuracy of staging investigations (n = 63). The article with the highest citation rate (38.00), defined as the number of citations divided by the number of complete years published, was Tixier et al. investigating PET texture analysis to predict treatment response to neo-adjuvant chemo-radiotherapy, cited 114 times since publication in 2011.

Conclusion

This bibliometric analysis has identified key publications regarded as important in radiological OC staging. Articles with the highest citation rates all investigated PET imaging, suggesting this modality could be the focus of future research.

Main Messages

• This study identifies key articles that investigate radiological staging of oesophageal cancer.

• The most common topic was accuracy of staging investigations.

• The article with the highest citation rate investigated the use of texture analysis in PET images.

Applications and limitations of radiomics

Radiomics is an emerging field in quantitative imaging that uses advanced imaging features to objectively and quantitatively describe tumour phenotypes. Radiomic features have recently drawn considerable interest due to its potential predictive power for treatment outcomes and cancer genetics, which may have important applications in personalized medicine. In this technical review, we describe applications and challenges of the radiomic field. We will review radiomic application areas and technical issues, as well as proper practices for the designs of radiomic studies.

Role of Radiotherapy and Newer Techniques in the Treatment of GI Cancers

The role of radiotherapy in multidisciplinary treatment of GI malignancies is well established. Recent advances in imaging as well as radiotherapy planning and delivery techniques have made it possible to target tumors more accurately while sparing normal tissues. Intensity-modulated radiotherapy is an advanced method of delivering radiation using cutting-edge technology to manipulate beams of radiation. The role of intensity-modulated radiotherapy is growing for many GI malignancies, such as cancers of the stomach, pancreas, esophagus, liver, and anus. Stereotactic body radiotherapy is an emerging treatment option for some GI tumors such as locally advanced pancreatic cancer and primary or metastatic tumors of the liver. Stereotactic body radiotherapy requires a high degree of confidence in tumor location and subcentimeter accuracy of the delivered dose. New image-guided techniques have been developed to overcome setup uncertainties at the time of treatment, including real-time imaging on the linear accelerator. Modern imaging techniques have also allowed for more accurate pretreatment staging and delineation of the primary tumor and involved sites. In particular, magnetic resonance imaging and positron emission tomography scans can be particularly useful in radiotherapy planning and assessing treatment response. Molecular biomarkers are being investigated as predictors of response to radiotherapy with the intent of ultimately moving toward using genomic and proteomic determinants of therapeutic strategies. The role of all of these new approaches in the radiotherapeutic management of GI cancers and the evolving role of radiotherapy in these tumor sites will be highlighted in this review.

Clinical tools to predict outcomes in patients with esophageal cancer treated with definitive chemoradiation: are we there yet?

Definitive chemoradiation (CRT) is a well-established treatment for esophageal cancer, but disease recurrence is common and many patients do not achieve initial remission with CRT alone. Predictors of outcome with CRT are needed to guide prognosis and further treatment decisions, in particular the need for post-CRT surgery. We review the role of baseline clinical factors, such as histology and tumor bulk, in predicting response to CRT. Post-CRT assessments, particularly PET imaging, may provide further information about the likelihood of complete response and survival, but the predictive power of clinical assessments remains limited. Emerging research on biomarkers holds promise for more tailored and accurate prediction of outcome with definitive CRT.

State-of-the-art molecular imaging in esophageal cancer management: implications for diagnosis, prognosis, and treatment

Molecular imaging techniques are increasingly being used in addition to standard imaging methods such as endoscopic ultrasound (EUS) and computed tomography (CT) for many cancers including those of the esophagus. In this review, we will discuss the utility of the most widely used molecular imaging technique, (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET). (18)F-FDG PET has a variety of potential applications ranging from improving staging accuracy at the time of initial diagnosis to assisting in radiation target volume delineation. Furthermore, (18)F-FDG PET can be used to evaluate treatment response after completion of neoadjuvant therapy or potentially during neoadjuvant therapy. Finally, we will also discuss other novel molecular imaging techniques that have potential to further improve cancer care.

Radiobiological Modeling Based on 18F-Fluorodeoxyglucose Positron Emission Tomography Data for Esophageal Cancer

Background

We investigated the relationship of standardized uptake values (SUVs) to radiobiological parameters, such a 25 s tumor control probability (TCP), to allow for quantitative prediction of tumor response based on SUVs from ¹⁸F fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) before and after treatment for esophageal cancer.

Methods

We analyzed data from 20 esophageal cancer patients treated with chemoradiotherapy (CRT) followed by surgery. Tumor pathologic response to CRT was assessed in surgical specimens. Patients underwent ¹⁸F-FDG PET imaging before and after CRT. Rigid image registration was performed between both images. Because TCP in a heterogeneous tumor is a function of average cell survival, we modeled TCP as a function of <SUV_R>, a possible surrogate for average cell survival (<SUV_R>=<SUV_after/SUV_before>). TCP was represented by a sigmoid function with two parameters: SUV_R50, the <SUV_R> at which TCP=0.5, and γ₅₀, the slope of the curve at SUV_R50. The two parameters and their confidence intervals (CIs) were estimated using the maximum-likelihood method. The correlation between SUV before CRT and SUV change <SUV_before – SUV_after> was also studied.

Results

A TCP model as a function of SUV before and after treatment was developed for esophageal cancer patients. The maximum-likelihood estimate of SUV_R50 was 0.47 (90% CI, 0.30-0.61) and for γ₅₀ was 1.62 (90% CI, 0-4.2). High initial SUV and larger metabolic response (larger <SUV_before –SUV_after>) were correlated, and this correlation was stronger among responders.

Conclusions

Our TCP model indicates that <SUV_after/SUV_before> is a possible surrogate for cell survival in esophageal cancer patients. Although CIs are large as a result of the small patient sample, parameters for a TCP curve can be derived and an individualized TCP can be calculated for future patients. Initial SUV does not predict response, whereas a correlation is found between surrogates for initial tumor burden and cell kill during therapy.

Comparison of texture features derived from static and respiratory-gated PET images in non-small cell lung cancer

BACKGROUND

PET-based texture features have been used to quantify tumor heterogeneity due to their predictive power in treatment outcome. We investigated the sensitivity of texture features to tumor motion by comparing static (3D) and respiratory-gated (4D) PET imaging.

METHODS

Twenty-six patients (34 lesions) received 3D and 4D [18F]FDG-PET scans before the chemo-radiotherapy. The acquired 4D data were retrospectively binned into five breathing phases to create the 4D image sequence. Texture features, including Maximal correlation coefficient (MCC), Long run low gray (LRLG), Coarseness, Contrast, and Busyness, were computed within the physician-defined tumor volume. The relative difference (δ3D-4D) in each texture between the 3D- and 4D-PET imaging was calculated. Coefficient of variation (CV) was used to determine the variability in the textures between all 4D-PET phases. Correlations between tumor volume, motion amplitude, and δ3D-4D were also assessed.

RESULTS

4D-PET increased LRLG ( = 1%-2%, p < 0.02), Busyness ( = 7%-19%, p < 0.01), and decreased MCC ( = 1%-2%, p < 7.5 × 10(-3)), Coarseness ( = 5%-10%, p < 0.05) and Contrast ( = 4%-6%, p > 0.08) compared to 3D-PET. Nearly negligible variability was found between the 4D phase bins with CV < 5% for MCC, LRLG, and Coarseness. For Contrast and Busyness, moderate variability was found with CV = 9% and 10%, respectively. No strong correlation was found between the tumor volume and δ3D-4D for the texture features. Motion amplitude had moderate impact on δ for MCC and Busyness and no impact for LRLG, Coarseness, and Contrast.

CONCLUSIONS

Significant differences were found in MCC, LRLG, Coarseness, and Busyness between 3D and 4D PET imaging. The variability between phase bins for MCC, LRLG, and Coarseness was negligible, suggesting that similar quantification can be obtained from all phases. Texture features, blurred out by respiratory motion during 3D-PET acquisition, can be better resolved by 4D-PET imaging. 4D-PET textures may have better prognostic value as they are less susceptible to tumor motion.

Pre-treatment metabolic tumor volume and total lesion glycolysis are useful prognostic factors for esophageal squamous cell cancer patients

OBJECTIVES

To study application of the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) with 18F-FDG PET/CT for predicting prognosis of esophageal squamous cell cancer (ESC) patients.

METHODS

Eighty-six patients with ESC staged from I to IV were prospectively enrolled. Cisplatin-based chemoradiotherapy (CCRT) or palliative chemoradiotherapy were the main treatment methods and none received surgery. 18F-FDG PET/CT scans were performed before the treatment. SUVmax, MTV, and TLG were measured for the primary esophageal lesion and regional lymph nodes. Receiver operating characteristic curves (ROCs) were generated to calculate the P value of the predictive ability and the optimal threshold.

RESULTS

MTV and TLG proved to be good indexes in the prediction of outcome for the ESC patients. An MTV value of 15.6 ml and a TLG value of 183.5 were optimal threshold to predict the overall survival (OS). The areas under the curve (AUC) for MTV and TLG were 0.74 and 0.70, respectively. Kaplan-Meier analysis showed an MTV less than 15.6 ml and a TLG less than 183.5 to indicate good media survival time (p value <0.05). In the stage III-IV patient group, MTV could better predict the OS (P < 0.001), with a sensitivity and specificity of 0.80 and 0.67, respectively.

CONCLUSIONS

Pre-treatment MTV and TLG are useful prognostic factors in non- surgical ESC.

Prognostic value of baseline FDG uptake on PET-CT in esophageal carcinoma

AIM: To evaluate the influence of baseline maximum standardized uptake value (SUV_max) on survival in a cohort of patients, undergoing positron emission tomography-computed tomography (PET-CT) scan for esophageal carcinoma.

METHODS: The pre-treatment SUV_max numeric reading was determined in patients with confirmed esophageal or junctional cancer having PET-CT scan during the time period 1^st January 2007 until 31^st July 2012. A minimum follow up of 12 mo was required. Patients were subdivided into quartiles according to SUV_max value and the influence of SUV_max on survival was assessed using univariate and multivariate analysis. The following pre-treatment factors were investigated: patient characteristics, tumor characteristics and planned treatment.

RESULTS: The study population was 271 patients (191 male) with esophageal or junctional carcinoma. The median age was 65 years (range 40-85) and histologic subtype was adenocarcinoma in 197 patients and squamous carcinoma in 74 patients. The treatment intent was radical in 182 and palliative in 89 patients. SUV_max was linked to histologic subtype (P = 0.008), tumor site (P = 0.01) and Union for International Cancer Control (UICC) stage (P < 0.001). On univariate analysis, prognosis was significantly associated with SUV_max (P = 0.001), T-stage (P < 0.001) and UICC stage (P < 0.001). On multivariate analysis, only T-stage and UICC stage remained significant.

CONCLUSION: Pretreatment SUV_max was not a useful marker in isolation for determining prognosis of patients with esophageal carcinoma.

Maximum standardized uptake value on PET/CT in preoperative assessment of lymph node metastasis from thoracic esophageal squamous cell carcinoma

The presence of lymph node metastasis is an important prognostic factor for patients with esophageal cancer. Accurate assessment of lymph nodes in thoracic esophageal carcinoma is essential for selecting appropriate treatment and forecasting disease progression. Positron emission tomography combined with computed tomography (PET/CT) is becoming an important tool in the workup of esophageal carcinoma. Here, we evaluated the effectiveness of the maximum standardized uptake value (SUVmax) in assessing lymph node metastasis in esophageal squamous cell carcinoma (ESCC) prior to surgery. Fifty-nine surgical patients with pathologically confirmed thoracic ESCC were retrospectively studied. These patients underwent radical esophagectomy with pathologic evaluation of lymph nodes. They all had ¹⁸F-FDG PET/CT scans in their preoperative staging procedures. None had a prior history of cancer. The pathologic status and PET/CT SUVmax of lymph nodes were collected to calculate the receiver operating characteristic (ROC) curve and to determine the best cutoff value of the PET/CT SUVmax to distinguish benign from malignant lymph nodes. Lymph node data from 27 others were used for the validation. A total of 323 lymph nodes including 39 metastatic lymph nodes were evaluated in the training cohort, and 117 lymph nodes including 32 metastatic lymph nodes were evaluated in the validation cohort. The cutoff point of the SUVmax for lymph nodes was 4.1, as calculated by ROC curve (sensitivity, 80%; specificity, 92%; accuracy, 90%). When this cutoff value was applied to the validation cohort, a sensitivity, a specificity, and an accuracy of 81%, 88%, and 86%, respectively, were obtained. These results suggest that the SUVmax of lymph nodes predicts malignancy. Indeed, when an SUVmax of 4.1 was used instead of 2.5, FDG-PET/CT was more accurate in assessing nodal metastasis.

New directions in perioperative management of locally advanced esophagogastric cancer

Cancers of the esophagus arise as adenocarcinomas and squamous cell carcinomas; these represent distinct diseases, with differing prognosis, yet they are often studied in common trials. With surgery alone, 5 year survival for T2-T3N0 disease is less than 30% to 40%, and declines to less than 25% with nodal involvement. The CROSS randomly assigned patients to surgery alone or to weekly carboplatin/paclitaxel X 5 and 41.4 Gy concurrent radiotherapy, followed by surgery. Seventy-five percent of enrolled patients had adenocarcinoma. Preoperative combined-modality therapy improved R0 resection from 69% to 92% (p &lt; 0.001 and improved median survival from 24 months to 49.4 months (p &lt; 0.003). This regimen reduced both locoregional recurrence (34% to 14%; p &lt; 0.001) and the development of peritoneal carcinomatosis (14% to 4%; p &lt; 0.001). Systemic perioperative therapy may have a greater effect on distant disease, the predominant mode of failure for these patients, and current trials compare preoperative chemoradiation with periooperative systemic therapy. PET scan response during preoperative chemotherapy without radiotherapy correlates with improvements in pathologic response and with improved survival. Nonresponse on early PET scan allows identifıcation of patients for earlier surgery and discontinuation of ineffective preoperative chemotherapy, without survival detriment. There is no predictive benefıt for early PET scan during the course of chemotherapy followed by chemoradiotherapy. The use of early PET scan during induction chemotherapy is being evaluated in CALGB/Alliance trial (NCT01333033). Molecular profıling has identifıed somatic gene mutations and pathways that may be oncogenic in upper gastrointestinal cancers. Potential targets include the epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR), HER2, mammalian target of rapamycin (mTOR), fıbroblast growth factor receptor (FGFR), MEK, and others. Targeted therapies with known survival benefit in esophagogastric cancer are currently limited to trastuzumab for HER2 overexpressing cancers, or ramicirumab.

Positron emission tomography imaging for gastroesophageal junction tumors

Positron emission tomography (PET) is now widely used in the initial evaluation of esophageal and gastroesophageal junction tumors. It can detect otherwise occult metastases, affecting staging and treatment in a significant proportion of patients. The intensity of PET uptake before treatment has been correlated with outcomes, but it remains uncertain whether PET is an independent prognostic factor for survival. An emerging application for PET is the assessment of response to induction chemotherapy or chemoradiotherapy. In particular, PET has the ability to discriminate treatment responders from nonresponders early in the course of induction chemotherapy. This can form the basis for further treatment decisions, such as a change in chemotherapy or the addition of concurrent radiotherapy, and this approach is now being tested in prospective trials. PET after concurrent chemoradiotherapy may also provide information regarding the utility of surgical resection. PET data can affect radiotherapy target definition, which may lead to improved tumor coverage in cases where the true extent of disease is not accurately reflected by computed tomography or endoscopic imaging.

Introduction to the analysis of PET data in oncology

Several reviews on specific topics related to positron emission tomography (PET) ranging in complexity from introductory to highly technical have already been published. This introduction to the analysis of PET data was written as a simple guide of the different phases of analysis of a given PET dataset, from acquisition to preprocessing, to the final data analysis. Although sometimes issues specific to PET in neuroimaging will be mentioned for comparison, most of the examples and applications provided will refer to oncology. Due to the limitations of space we couldn't address each issue comprehensively but, rather, we provided a general overview of each topic together with the references that the interested reader should consult. We will assume a familiarity with the basic principles of PET imaging.

Relationship between (18)F-fluorodeoxyglucose uptake in primary lesions and clinicopathological characteristics of esophageal squamous cell carcinoma patients

The aim of this study, was to investigate the relationship between ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake in primary tumors and the clinicopathological characteristics of esophageal squamous cell carcinoma (ESCC) patients. Patients with histopathologically diagnosed ESCC who had received a pre-therapeutic ¹⁸F-FDG positron emission tomography-computed tomography (PET-CT) scan were enrolled in the study. The maximum standardized uptake value (SUVmax) and the length of the primary tumor were measured by PET-CT. The clinical tumor-node-metastasis (TNM) stage was determined mainly by PET-CT images according to the American Joint Committee on Cancer (AJCC) staging system, 2002. A significant difference was observed in SUVmax between the length and T stage of the primary tumor (P=0.000 and P=0.017, respectively), but not in the grade of tumor differentiation (P=0.383), clinical stage (P=0.583), N staging (P=0.387), M staging (P=0.886), patient age (P= 0.752) or gender (P=0.233). There was a significant positive correlation between the SUVmax and the length of the tumor (r=0.456, P=0.000) and the depth of invasion of the primary tumor (r=0.257, P=0.006). After controlling for length, no statistically significant correlation was found between T stage and SUVmax (r=0.074, P=0.537). In conclusion, these findings suggest that tumor length influences FDG uptake in ESCC tumors, and that the T stage of the primary tumor is not significantly correlated with the SUVmax after controlling for length. However, we did not find a significant correlation between the SUVmax and primary tumor differentiation and clinical stage. These data provide important information for the management of ESCC.

Prognostic significance of 18-FDG PET/CT and EUS-defined tumour characteristics in patients with oesophageal cancer

AIM

To determine the correlation between 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography/computed tomography (PET/CT) defined maximum standardized uptake value (SUVmax) and endoluminal ultrasound-defined tumour volume (EDTV) in patients with oesophageal cancer (OC) and their relative prognostic significance.

MATERIALS AND METHODS

One hundred and eighty-five consecutive patients with OC were staged using CT, endoscopic ultrasound (EUS), and PET/CT. The maximum potential EDTV was calculated (πr(2)L, where r = tumour thickness and L = total length of disease including proximal and distal lymph node metastases). Primary outcome measure was survival from diagnosis.

RESULTS

Ninety-one percent of patients (168/185) had FDG-avid tumours on PET/CT. SUVmax correlated positively and significantly with EDTV (Spearman's rho = 0.339, p = 0.001). On univariate analysis, survival was inversely related to the PET/CT lymph node metastasis count (LNMC, p = 0.015), EUS N stage (p = 0.002), EDTV (<48 cm(3), p = 0.001), EUS total length of disease (p = 0.001), SUVmax (p = 0.002), PET/CT N stage (p < 0.0001), and EUS LNMC (p < 0.0001). On multivariate analysis two factors were significantly and independently associated with survival: EDTV (HR, 3.118; 95% CI: 1.357-7.167; p = 0.007), and PET/CT N stage (HR, 0.496; 95% CI: 0.084-1.577; p = 0.022).

CONCLUSION

EDTV and PET/CT N stage were important predictors of survival and further research is needed to identify critical prognostic values.

Symptomatic cardiac toxicity is predicted by dosimetric and patient factors rather than changes in 18F-FDG PET determination of myocardial activity after chemoradiotherapy for esophageal cancer

PURPOSE

To determine factors associated with symptomatic cardiac toxicity in patients with esophageal cancer treated with chemoradiotherapy.

MATERIAL AND METHODS

We retrospectively evaluated 102 patients treated with chemoradiotherapy for locally advanced esophageal cancer. Our primary endpoint was symptomatic cardiac toxicity. Radiation dosimetry, patient demographic factors, and myocardial changes seen on (18)F-FDG PET were correlated with subsequent cardiac toxicity. Cardiac toxicity measured by RTOG and CTCAE v3.0 criteria was identified by chart review.

RESULTS

During the follow up period, 12 patients were identified with treatment related cardiac toxicity, 6 of which were symptomatic. The mean heart V20 (79.7% vs. 67.2%, p=0.05), V30 (75.8% vs. 61.9%, p=0.04), and V40 (69.2% vs. 53.8%, p=0.03) were significantly higher in patients with symptomatic cardiac toxicity than those without. We found the threshold for symptomatic cardiac toxicity to be a V20, V30 and V40 above 70%, 65% and 60%, respectively. There was no correlation between change myocardial SUV on PET and cardiac toxicity, however, a greater proportion of women suffered symptomatic cardiac toxicity compared to men (p=0.005).

CONCLUSIONS

A correlation did not exist between percent change in myocardial SUV and cardiac toxicity. Patients with symptomatic cardiac toxicity received significantly greater mean V20, 30 and 40 values to the heart compared to asymptomatic patients. These data need validation in a larger independent data set.

Metabolic response at repeat PET/CT predicts pathological response to neoadjuvant chemotherapy in oesophageal cancer

OBJECTIVES

Reports have suggested that a reduction in tumour 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) examination during or after neoadjuvant chemotherapy may predict pathological response in oesophageal cancer. Our aim was to determine whether metabolic response predicts pathological response to a standardised neoadjuvant chemotherapy regimen within a prospective clinical trial.

METHODS

Consecutive patients staged with potentially curable oesophageal cancer who underwent treatment within a non-randomised clinical trial were included. A standardised chemotherapy regimen (two cycles of oxaliplatin and 5-fluorouracil) was used. PET/CT was performed before chemotherapy and repeated 24-28 days after the start of cycle 2.

RESULTS

Forty-eight subjects were included: mean age 65 years; 37 male. Using the median percentage reduction in SUV(max) (42%) to define metabolic response, pathological response was seen in 71% of metabolic responders (17/24) compared with 33% of non-responders (8/24; P = 0.009, sensitivity 68%, specificity 70%). Pathological response was seen in 81% of subjects with a complete metabolic response (13/16) compared with 38% of those with a less than complete response (12/32; P = 0.0042, sensitivity 52%, specificity 87%). There was no significant histology-based effect.

CONCLUSIONS

There was a significant association between metabolic response and pathological response; however, accuracy in predicting pathological response was relatively low.

Accuracy of PET-CT in predicting survival in patients with esophageal cancer

BACKGROUND

Positron emission tomography (PET) is an integral part of tumor staging for patients with esophageal cancer. Recent studies suggest a role for PET scan in predicting survival in these patients, but this relationship is unclear in the setting of neoadjuvant therapy. We examined pretreatment maximum standard uptake value (SUV(max)) of the primary tumor in patients treated with and without neoadjuvant therapy.

METHODS

All patients undergoing esophagectomy with a preoperative PET scan over a nine-year period (2001-2010) were identified from a prospectively maintained database. Positron emission tomography data were obtained from computers housing the original PET scans. Overall survival was correlated with SUV(max) of the primary tumor.

RESULTS

A total of 191 patients were identified, and 103 patients met inclusion criteria. Eighty-two had an adenocarcinoma (80%), and 21 (20%) had a squamous cell carcinoma. Fifty-seven (55%) patients received neoadjuvant therapy. In the surgery alone group, a SUV(max) of > 5.0 in the primary tumor was associated with poor prognosis [Hazard Ratio (HR) 0.32; p = 0.007], but this factor did not retain its significance on multivariate analysis (HR 0.65; p = 0.43). Pretreatment SUV(max) in patients who underwent neoadjuvant therapy was not significant in predicting overall survival (p = 0.10).

CONCLUSIONS

This study does not support the use of SUV(max) on pretreatment PET scans as a prognostic tool for patients with esophageal cancer, especially in those who have received neoadjuvant therapy. Lymph node status is a more accurate predictor of outcome, and efforts to improve pretreatment staging should focus on this factor.

Standardized uptake value by positron emission tomography/computed tomography as a prognostic variable in metastatic breast cancer

BACKGROUND

In this retrospective, single-institution study, the authors examine the maximum standardized uptake value (SUVmax) on positron emission tomography/computed tomography (PET/CT) images as a prognostic variable in patients with newly diagnosed metastatic breast cancer (MBC).

METHODS

Patients with ≥1 metastatic lesion on PET/CT images that were obtained within 60 days of their MBC diagnosis between January 1, 2001 and December 31, 2008 were included. Patients were excluded if they had received chemotherapy ≤30 days before the PET/CT images were obtained. Electronic medical reports were reviewed to determine the SUVmax and overall survival. Because of intraindividual variation in the SUV by body site, separate analyses were conducted by metastatic site. Relationships between site-specific PET/CT variable tertiles and overall survival were assessed using Cox regression; hazard ratios for the highest tertile versus the lowest tertile were reported.

RESULTS

In total, 253 patients were identified, and their median age was 57 years (range, 27-90 years). Of these, 152 patients (60%) died, and the median follow-up was 40 months. On univariate analysis, SUVmax tertile was strongly associated with overall survival in patients who had bone metastases (N = 141; hazard ratio, 3.13; 95% confidence interval, 1.79-5.48; P < .001). This effect was maintained on multivariate analysis (HR = 3.19; 95% confidence interval, 1.64-6.20, P = .002) after correcting for known prognostic variables. A greater risk of death was associated with SUVmax tertile in patients who had metastases to the liver (N = 46; hazard ratio, 2.07; 95% confidence interval, 0.90-4.76), lymph nodes (N = 149; hazard ratio, 1.1; 95% confidence interval, 0.69-1.88), and lung (N = 62; hazard ratio, 2.2; 95% confidence interval, 0.97-4.95), although these results were not significant (P = .18, P = .31, and P = .095, respectively).

CONCLUSIONS

The current results indicate that PET/CT has value as a prognostic tool in patients with newly diagnosed MBC to bone.

Role of positron emission tomography-computed tomography in predicting survival after neoadjuvant chemotherapy and surgery for oesophageal adenocarcinoma

BACKGROUND

Positron emission tomography combined with computed tomography (PET-CT) is increasingly being used in the staging of oesophageal cancer. Some recent reports suggest it may be used to predict survival. None of these studies, however, reported on the prognostic value of PET-CT performed before neoadjuvant chemotherapy and surgery. The aim of this study was to determine whether pretreatment PET-CT could predict survival.

METHODS

Consecutive patients with oesophageal adenocarcinoma who underwent PET-CT before neoadjuvant chemotherapy and resection were included. Maximum standardized uptake value (SUV(max)), fluorodeoxyglucose (FDG)-avid tumour length and the presence of FDG-avid local lymph nodes were determined for all patients. Kaplan-Meier survival analysis was performed and multivariable analysis used to identify independent prognostic factors.

RESULTS

A total of 121 patients were included (mean age 63 years, 97 men) of whom 103 underwent surgical resection. On an intention-to-treat basis, overall survival was significantly worse in patients with FDG-avid local lymph nodes (P < 0·001). SUV(max) and FDG-avid tumour length did not predict survival (P = 0·276 and P = 0·713 respectively). The presence of FDG-avid local lymph nodes was an independent predictor of poor overall survival (hazard ratio (HR) 4·75, 95 per cent confidence interval 2·14 to 10·54; P < 0·001) and disease-free survival (HR 2·97, 1·40 to 6·30; P = 0·004).

CONCLUSION

The presence of FDG-avid lymph nodes, but not SUV(max) or FDG-avid tumour length, was an independent adverse prognostic factor.

Prognostic significance of SUV on PET/CT in patients with localised oesophagogastric junction cancer receiving neoadjuvant chemotherapy/chemoradiation:a systematic review and meta-analysis

OBJECTIVE

The objective of this study was to comprehensively review the evidence for use of pre-treatment, post-treatment and changes in tumour glucose uptake that were assessed by 18-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET) early, during or immediately after neoadjuvant chemotherapy/chemoradiation to predict prognosis of localised oesophagogastric junction (AEG) cancer.

METHODS

We searched for articles published in English; limited to AEG; (18)F-FDG uptake on PET performed on a dedicated device; dealt with the impact of standard uptake value (SUV) on survival. We extracted an estimate of the log hazard ratios (HRs) and their variances and performed meta-analysis.

RESULTS

798 patients with AEG were included. And the scan time for (18)F-FDG-PET was as follows: prior to therapy (PET1, n=646), exactly 2 weeks after initiation of neoadjuvant therapy (PET2, n=245), and pre-operatively (PET3, n=278). In the two meta-analyses for overall survival, including the studies that dealt with reduction of tumour maximum SUV (SUV(max)) (from PET1 to PET2/PET3 and from PET1 to PET2), the results were similar, with the overall HR for non-responders being 1.83 [95% confidence interval (CI), 1.41-2.36] and 2.62 (95% CI, 1.61-4.26), respectively; as for disease-free survival, the combined HR was 2.92 (95% CI, 2.08-4.10) and 2.39 (95% CI, 1.57-3.64), respectively. The meta-analyses did not attribute significant prognostic values to SUV(max) before and during therapy in localised AEG.

CONCLUSION

Relative changes in FDG-uptake of AEG are better prognosticators. Early metabolic changes from PET1 to PET2 may provide the same accuracy for prediction of treatment outcome as late changes from PET1 to PET3.

Optimizing neoadjuvant chemotherapy through the use of early response evaluation by positron emission tomography

Metabolic imaging and early response assessment by positron emission tomography (PET) may guide treatment of localized esophageal cancers. The most consistent and validated results have been obtained during neoadjuvant treatment of adenocarcinoma of the esophago-gastric junction (AEG). It was demonstrated that 18F-Fluorodeoxyglucoe (FDG)-PET is highly accurate for identifying non-responding tumors within 2 weeks after the initiation of neoadjuvant chemotherapy when a quantitative threshold for metabolic response is used. In consecutive phase II studies the metabolic activity, defined by the standardized uptake (SUV) of 18-FDG before and during chemotherapy, was measured. Significant decreases of the SUV after only two weeks of induction chemotherapy were observed. A drop of >35 % 2 weeks after the start of chemotherapy revealed as an accurate cut-off value to predict response after a 12-week course of preoperative chemotherapy. This cut-off was recently confirmed in a US study, where investigators did follow-up PET not 14 days but 6 weeks after initiation of chemotherapy. It was further noticed that the metabolic response to induction chemotherapy revealed as an independent prognostic factor in locally advanced AEG. Therefore, PET could be used to tailor treatment according to the sensitivity of an individual tumor. This concept was realized in the MUNICON-1 and -2 trials. These trials prospectively confirmed that responders to induction chemotherapy can be identified by early metabolic imaging using FDG-PET. Continuing neoadjuvant chemotherapy in the responding population resulted in a favorable outcome. Moreover, MUNICON-1 showed that chemotherapy can be discontinued at an early stage in metabolic non-responders without compromising the patients' prognosis, but saving time and reducing side effects and costs. MUNICON-2 showed that the addition of neoadjuvant radiation therapy in metabolic nonresponders did not lead to an improvement of their poor prognosis, thus showing that early metabolic nonresponse indicates dismal tumor biology. Future studies need to validate the prognostic and predictive value of PET in multicenter settings and in conjunction with different neoadjuvant chemotherapy and chemo-immunotherapy regimens.

Role of (18F) 2-fluoro-2-deoxyglucose positron emission tomography in upper gastrointestinal malignancies

The role of whole-body FDG [(¹⁸F) 2-fluoro-2-deoxyglucose] positron emission tomography (PET) scanning as an imaging modality in the management of patients with malignancy has evolved enormously over the past two decades. FDG-PET has demonstrated significant efficacy in the staging, prognostication and detection of occult metastatic disease in malignancies of the gastrointestinal tract, in addition to assessment of the response to cytotoxic chemotherapy in a more timely manner than has traditionally been possible by more conventional imaging tools. The sensitivity and specificity of FDG-PET for the detection and staging of malignancy depend not only on the site and size of the primary tumor and metastases, but also on histological cell type, reflecting underlying disparities in glucose metabolism. The metabolic response to neo-adjuvant chemotherapy or to chemo-radiotherapy in cancers of the gastro-esophageal junction or stomach has been demonstrated in several prospective studies to correlate significantly with both the histological tumor response to treatment and with consequent improvements in overall survival. This may offer a future paradigm of personalized treatment based on the PET response to chemotherapy. FDG-PET has been less successful in efforts to screen for and detect recurrent upper gastrointestinal malignancies, and in the detection of low volume metastatic peritoneal disease. Efforts to improve the accuracy of PET include the use of novel radiotracers such as (¹⁸F) FLT (3-deoxy-3-fluorothymidine) or ¹¹C-choline, or fusion PET-CT with concurrent high-resolution computed tomography. This review focuses on the role of FDG-PET scanning in staging and response assessment in malignancies of the upper gastrointestinal tract, specifically gastric, esophageal and pancreas carcinoma.

New trends for staging and therapy for localized gastroesophageal cancer: the role of PET

Treatment options for localized gastroesophageal cancers reach from limited resection to multimodality treatment. Accurate clinical assessment, prognostic and predictive information are needed to select the most appropriate treatment approach. Positron emission tomography (PET) in combination with computed tomography (CT) in a hybrid imaging modality PET-CT may refine the staging accuracy and add prognostic information. Moreover, experiences from diverse centers indicate that PET also might improve significantly the assessment of response to preoperative chemotherapy and chemoradiotherapy. This article outlines the current value of PET in the staging and multidisciplinary care of gastroesophageal cancer. At this stage, it remains unclear whether the prognosis of patients can be improved by implementing PET in the management of localized disease. Prospective multicenter studies have to be carried out to validate metabolic cut-off values and to prove the benefit of PET-guided treatment decisions.

Update: modern approaches to the treatment of localized esophageal cancer

The optimal treatment strategy for esophageal cancer continues to be a topic of debate. Improvements in chemotherapy drugs, surgical techniques, and radiotherapy planning and delivery have led to the design of treatment approaches that are specific to both the stage of the tumor and the overall performance status of the patient. Surgery continues to be the standard treatment option for localized disease, but multimodality treatments that include radiation and chemotherapy with surgery are increasingly used. The next few years will continue to see improvements in radiation techniques, especially proton beam treatment; the development of additional minimally invasive surgical approaches to minimize postoperative side effects; and the discovery of molecular biomarkers to help specifically target treatment of esophageal cancer in individual patients.

Clinical significance of primary lesion FDG uptake for choice between oesophagectomy and endoscopic submucosal dissection for resectable oesophageal squamous cell carcinomas

OBJECTIVES

To correlate primary oesophageal squamous cell carcinoma (SCC) (18)F-fluoro-deoxyglucose (FDG) uptake with pathological factors and examine its significance regarding choice of therapy.

METHODS

We retrospectively examined the factors affecting visible and non-visible FDG uptake in 37 primary lesions in 32 oesophageal SCC patients who underwent PET/CT before oesophagectomy or endoscopic submucosal dissection (ESD). We divided the lesions into pathological depth invasion ≥sm2 oesophagectomy (n = 18) and ≤sm1 ESD (n = 19) indicated groups and compared the diagnostic accuracy of FDG-PET with that of endoscopic ultrasound (EUS) performed for 23 superficial lesions to discriminate between these groups.

RESULTS

There were 17 visible and 20 non-visible lesions. The lesion visibility was significantly higher in the larger (≥40 mm), non-flat type, more deeply invaded, positive vascular invasion (P < 0.001 each), positive nodal metastasis (P = 0.04) and higher Glut-1 score (P = 0.005) tumour groups. When the visible and non-visible lesions indicated a need for oesophagectomy and ESD respectively, the sensitivity, specificity and accuracy of oesophagectomy were 94% (17/18), 100% (19/19) and 97% (36/37) and those of EUS were 75% (3/4), 79% (15/19) and 78% (18/23) respectively.

CONCLUSIONS

Primary lesion FDG visibility can be one of the indicators for choosing between oesophagectomy and ESD for resectable oesophageal SCCs.

The challenges of integrating molecular imaging into the optimization of cancer therapy

We review novel, in vivo and tissue-based imaging technologies that monitor and optimize cancer therapeutics. Recent advances in cancer treatment centre around the development of targeted therapies and personalisation of treatment regimes to individual tumour characteristics. However, clinical outcomes have not improved as expected. Further development of the use of molecular imaging to predict or assess treatment response must address spatial heterogeneity of cancer within the body. A combination of different imaging modalities should be used to relate the effect of the drug to dosing regimen or effective drug concentration at the local site of action. Molecular imaging provides a functional and dynamic read-out of cancer therapeutics, from nanometre to whole body scale. At the whole body scale, an increase in the sensitivity and specificity of the imaging probe is required to localise (micro)metastatic foci and/or residual disease that are currently below the limit of detection. The use of image-guided endoscopic biopsy can produce tumour cells or tissues for nanoscopic analysis in a relatively patient-compliant manner, thereby linking clinical imaging to a more precise assessment of molecular mechanisms. This multimodality imaging approach (in combination with genetics/genomic information) could be used to bridge the gap between our knowledge of mechanisms underlying the processes of metastasis, tumour dormancy and routine clinical practice. Treatment regimes could therefore be individually tailored both at diagnosis and throughout treatment, through monitoring of drug pharmacodynamics providing an early read-out of response or resistance.