18F-FDG PET and 18F-FDG PET/CT for Assessing Response to Therapy in Esophageal Cancer

SFXN1 as a potential diagnostic and prognostic biomarker of LUAD is associated with 18F-FDG metabolic parameters

BACKGROUND

Sideroflexin 1 (SFXN1) has been discovered as a novel tumor marker for lung adenocarcinoma, but data on its importance in the development of lung adenocarcinoma is still limited. This study evaluated the correlation between SFXN1 and parameters related to 18F-flurodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT), and further explored the role of SFXN1 in the value-added and glycolytic processes of LUAD.

METHOD

The expression and prognostic value of SFXN1 mRNA in LUAD were analyzed using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) data base. Retrospective analysis of 18F-FDG PET imaging and metabolic parameters in 42 patients to explore the relationship between the expression of SFXN1 and glucose metabolism levels in lung adenocarcinoma and its clinical significance. H1975 cells were selected as the in vitro research object, and the biological effects of SFXN1 on LUAD were further elucidated through Edu proliferation assay, CCK8 activity assay, wound healing experiment, and cell flow cytometry.

RESULT

SFXN1 is highly expressed in various tumors, including LUAD, and its high expression can serve as an independent predictor of overall survival in lung adenocarcinoma. In addition, the expression of SFXN1 in LUAD was significantly correlated with 18F-FDG PET/CT parameters: maximum and average standardized uptake values (SUVmax and SUVmean), as well as total lesion glycolysis (TLG) (rho = 0.574, 0.589, and 0.338, p < 0.05), which can predict the expression of SFXN1 with an accuracy of 0.934. In vitro functional experiments have shown that knocking down SFXN1 inhibits the proliferation and migration of LUAD cells, promotes cell apoptosis, and may inhibit tumor activity by regulating the expression of glycolytic related genes SLC2A1, HK2, GPI, ALDOA, GAPDH, ENO1, PKM, and LDHA.

CONCLUSION

The overexpression of SFXN1 is closely related to FDG uptake, and SFXN1, as a promising prognostic biomarker, may mediate the development of LUAD through the glycolytic pathway.

Role of Textural Analysis of Pretreatment 18F Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Response Prediction in Esophageal Carcinoma Patients

Introduction

Positron emission tomography/computed tomography (PET/CT) is routinely used for staging, response assessment, and surveillance in esophageal carcinoma patients. The aim of this study was to investigate whether textural features of pretreatment 18F-fluorodeoxyglucose (18F-FDG) PET/CT images can contribute to prognosis prediction in carcinoma oesophagus patients.

Materials and Methods

This is a retrospective study of 30 diagnosed carcinoma esophagus patients. These patients underwent pretreatment 18F-FDG PET/CT for staging. The images were processed in a commercially available textural analysis software. Region of interest was drawn over primary tumor with a 40% threshold and was processed further to derive 92 textural and radiomic parameters. These parameters were then compared between progression group and nonprogression group. The original dataset was subject separately to receiver operating curve analysis. Receiver operating characteristic (ROC) curves were used to identify the cutoff values for textural features with a P < 0.05 for statistical significance. Feature selection was done with principal component analysis. The selected features of each evaluator were subject to 4 machine-learning algorithms. The highest area under the curve (AUC) values was selected for 10 features.

Results

A retrospective study of 30 primary carcinoma esophagus patients was done. Patients were followed up after chemo-radiotherapy and they underwent follow-up PET/CT. On the basis of their response, patients were divided into progression group and nonprogression group. Among them, 15 patients showed disease progression and 15 patients were in the nonprogression group. Ten textural analysis parameters turned out to be significant in the prediction of disease progression. Cutoff values were calculated for these parameters according to the ROC curves, GLZLM_long zone emphasis (Gray Level Zone Length Matrix)_long zone emphasis (44.9), GLZLM_low gray level zone emphasis (0.006), GLZLM_short zone low gray level emphasis (0.0032), GLZLM_long zone low gray level emphasis (0.185), GLRLM_long run emphasis (Gray Level Run Length Matrix) (1.31), GLRLM_low gray level run emphasis (0.0058), GLRLM_short run low gray level emphasis (0.005496), GLRLM_long run low gray level emphasis (0.00727), NGLDM_Busyness (Neighborhood Gray Level Difference Matrix) (0.75), and gray level co-occurrence matrix_homogeneity (0.37). Feature selection by principal components analysis and feature classification by the K-nearest neighbor machine-learning model using independent training and test samples yielded the overall highest AUC.

Conclusions

Textural analysis parameters could provide prognostic information in carcinoma esophagus patients. Larger multicenter studies are needed for better clinical prognostication of these parameters.

eIF6 is potential diagnostic and prognostic biomarker that associated with 18F-FDG PET/CT features and immune signatures in esophageal carcinoma

Background

Although eukaryotic initiation factor 6 (eIF6) is a novel therapeutic target, data on its importance in the development of esophageal carcinoma (ESCA) remains limited. This study evaluated the correlation between eIF6 expression and metabolic analysis using fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) -Positron emission tomography (PET) and immune gene signatures in ESCA.

Methods

This study employed The Cancer Genome Atlas (TCGA) to analyze the expression and prognostic value of eIF6, as well as its relationship with the immune gene signatures in ESCA patients. The qRT-PCR and Western blot analyses were used to profile the expression of eIF6 in ESCA tissues and different ESCA cell lines. The expression of tumor eIF6 and glucose transporter 1 (GLUT1) was examined using immunohistochemical tools in fifty-two ESCA patients undergoing routine ¹⁸F-FDG PET/CT before surgery. In addition, the cellular responses to eIF6 knockdown in human ESCA cells were assessed via the MTS, EdU, flow cytometry and wound healing assays.

Results

Our data demonstrated that compared with the normal esophageal tissues, eIF6 expression was upregulated in ESCA tumor tissues and showed a high diagnostic value with an area under curve of 0.825 for predicting ESCA. High eIF6 expression was significantly correlated with shorter overall survival of patients with esophagus adenocarcinoma (p = 0.038), but not in squamous cell carcinoma of the esophagus (p = 0.078). In addition, tumor eIF6 was significantly associated with ¹⁸F-FDG PET/CT parameters: maximal and mean standardized uptake values (SUVmax and SUVmean) and total lesion glycolysis (TLG) (rho = 0.458, 0.460, and 0.300, respectively, p < 0.01) as well as GLUT1 expression (rho = 0.453, p < 0.001). A SUVmax cutoff of 18.2 led to prediction of tumor eIF6 expression with an accuracy of 0.755. Functional analysis studies demonstrated that knockdown of eIF6 inhibited ESCA cell growth and migration, and fueled cell apoptosis. Moreover, the Bulk RNA gene analysis revealed a significant inverse association between eIF6 and the tumor-infiltrating immune cells (macrophages, T cells, or Th1 cells) and immunomodulators in the ESCA microenvironment.

Conclusion

Our study suggested that eIF6 might serve as a potential prognostic biomarker associated with metabolic variability and immune gene signatures in ESCA tumor microenvironment.

Significance of mid-radiotherapy 18F-fluorodeoxyglucose positron emission tomography/computed tomography in esophageal cancer

BACKGROUND AND PURPOSE

Metabolic parameters evaluated by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) are known as prognostic markers in various cancers. We aimed to validate the predictive value of mid-radiotherapy (RT) FDG PET/CT parameters in esophageal cancer.

MATERIALS AND METHODS

Eighty-three patients treated with RT with or without chemotherapy between 2015 and 2020 were included. PET parameters including metabolic tumor volume (MTV), total lesion glycolysis, and mean (SUV_mean) and maximum standardized uptake value (SUV_max) were analyzed. Locoregional recurrence-free rate (LRFR) and distant metastasis-free rate (DMFR) were analyzed.

RESULTS

The median follow-up period was 10.5 months. Mid-RT SUV_max was significantly associated with LRFR (HR 1.07, p = 0.009) and DMFR (HR 1.13, p=0.047) while mid-RT MTV was associated with DMFR (HR 1.06, p=0.007). Treatment response after RT was associated with overall survival (HR, 1.52, p=0.025). Further, treatment response was significantly associated with mid-RT SUV_max. The optimal cutoff value for mid-RT SUV_max in predicting LRFR and DMFR was 11 while cutoff value for mid-RT MTV was 15. The patients with mid-RT SUV_max≤11 showed superior LRFR and DMFR compared to SUV_max>11 (1-year LRFR; 73.4% vs 48.4%, p=0.028, 1-year DMFR; 74.6% vs 40.7%, p=0.007). The 1-year DMFR was significantly different between patients with mid-RT MTV≤15 and >15 (1-year DMFR; 78.2% vs 31.9%, p=0.002).

CONCLUSION

Tumor metabolism changes during RT can be a useful predictive tool for treatment response and recurrence in patients with esophageal cancer. Clinicians may consider early response evaluation with PET during RT for information about prognosis.

Comparison of treatment response assessed by 18F-FDG PET/CT with the histopathological response using tumor regression grading on surgically resected specimen following neoadjuvant chemotherapy in squamous cell carcinoma of esophagus

BACKGROUND

For the response assessment after chemotherapy, gold standard is always the histopathological response. However, metabolic response can also guide further treatment. Herein, this study aimed to evaluate metabolic response assessment to neoadjuvant chemotherapy in squamous cell carcinoma esophagus using PET response criteria in solid tumors (PERCIST) criteria with taking histopathological response by tumor regression grading as the standard method.

METHODS

Total fifty-seven patients with squamous cell carcinoma esophagus were enrolled between April 2017 to December 2018 for this prospective study. All patients were undergone for baseline PET scan before going for neoadjuvant chemotherapy. Repeat PET scan was done after neoadjuvant chemotherapy. Operable patients were taken for surgery. Final histological response was assessed by Mandard grading. Three metabolic tools [maximum standardized uptake value (SUVmax), tumor regression grading, PERCIST] were compared.

RESULTS

The mean SULpeak of the primary lesion was 11.7 ± 5.5 (median, 10.2, range 5.5-31.8). The average percentage change (%Δ) in SUVmax was 42.9 ± 26.3. On histopathology, 5 (13.1%) patients showed complete pathological response, whereas grade II, III, IV and V in 8 (21.1%), 12 (31.6%), 10 (26.3%) and 3 (7.8%) respectively. On comparison of PERCIST with Mandard grading, agreement analysis showed that there was moderate agreement (k, 0.48). %ΔSUV peak change showed a strong correlation with %ΔSUVmax (P = 0.01) and percentage tumor to liver ratio change (P = 0.01). On comparison, these metabolic response tools showed a weak agreement (k, 0.28 with tumor to liver ratio, k, 0.38 with SUVmax).

CONCLUSION

After neoadjuvant chemotherapy, 18F-fluorodeoxyglucose PET/CT can help to assess the response and guide the treatment. However, a larger study is warranted to evaluate their correlation with pathological response.

Prognostic values of mid-radiotherapy 18F-FDG PET/CT in patients with esophageal cancer

BACKGROUND

To identify whether early metabolic responses as determined using ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) during radiotherapy (RT) predict outcomes in patients with esophageal cancer.

METHODS

Twenty-one patients with esophageal cancer who received pre-treatment ¹⁸F-FDG PET/CT (PET1) and inter-fractional ¹⁸F-FDG PET/CT (PET2) after 11 fractions of RT (median 23.1 Gy, 2.1 Gy per fraction) were retrospectively reviewed. The region of interest for each calculation was delineated using "PET Edge". We calculated PET parameters including maximum and mean standardized uptake values (SUV_max and SUV_mean, respectively), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). The relative changes (%) were calculated using the logarithmically transformed parameter values for the PET1 and PET2 scans. Multivariate analysis of locoregional recurrence and distant failures were performed using Cox regression analysis. After identifying statistically significant PET parameters for discriminating responders from non-responders, receiver operating characteristics curve analyses were used to assess the potentials of the studied PET parameters.

RESULTS

After a median follow-up of 13 months, the 1-year overall and progression-free survival rates were 79.0% and 34.4%, respectively. Four patients developed locoregional recurrences (LRRs) and 8 had distant metastases (DMs). The 1-year overall LRR-free rate was 76.9% while the DM-free rate was 60.6%. The relative changes in MTV (ΔMTV) were significantly associated with LRR (p = 0.03). Conversely, the relative changes in SUV_mean (ΔSUV_mean) were associated with the risk of DM (p = 0.02). An ΔMTV threshold of 1.14 yielded a sensitivity of 60%, specificity of 94%, and an accuracy of 86% for predicting an LRR. Additionally, a ΔSUV_mean threshold of a 35% decrease yielded a sensitivity of 67%, specificity of 83%, and accuracy of 76% for the prediction DM.

TRIAL REGISTRATION

Retrospectively registered.

CONCLUSIONS

Changes in tumor metabolism during RT could be used to predict treatment responses, recurrences, and prognoses in patients with esophageal cancer.

PET Imaging Biomarkers of Anti-EGFR Immunotherapy in Esophageal Squamous Cell Carcinoma Models

Epidermal growth factor receptor (EGFR) is overexpressed and considered as a proper molecular target for diagnosis and targeted therapy of esophageal squamous cell carcinoma (ESCC). This study evaluated the usefulness of PET imaging biomarkers with ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET for anti-EGFR immunotherapy in ESCC models. In vivo EGFR status and glucose metabolism by cetuximab treatment were evaluated using ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET, respectively. Therapeutic responses with imaging biomarkers were confirmed by western blot and immunohistochemistry. TE-4 and TE-8 tumors were clearly visualized by ⁶⁴Cu-PCTA-cetuximab, and EGFR expression on TE-8 tumors showed 2.6-fold higher uptake than TE-4. Tumor volumes were markedly reduced by cetuximab in TE-8 tumor (92.5 ± 5.9%), but TE-4 tumors were refractory to cetuximab treatment. The SUVs in ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET images were statistically significantly reduced by cetuximab treatment in TE-8 but not in TE-4. ⁶⁴Cu-PCTA-cetuximab and ¹⁸F-FDG-PET images were well correlated with EGFR and pAkt levels. ⁶⁴Cu-PCTA-cetuximab immuno-PET had a potential for determining EGFR level and monitoring therapeutic response by anti-EGFR therapy. ¹⁸F-FDG-PET was also attractive for monitoring efficacy of anti-EGFR therapy. In conclusion, PET imaging biomarkers may be useful for selecting patients that express target molecules and for monitoring therapeutic efficacy of EGFR-targeted therapy in ESCC patients.

Beyond Correlations, Sensitivities, and Specificities: Case Examples of the Evaluation of Advanced Imaging in Oncology Clinical Trials and Cancer Treatment

Although advanced imaging is an important component of oncology clinical trials, there has not been a lot of success in advancing its use from a research perspective. One likely reason is the lack of consensus on the methodology used to study advanced imaging in trials, which results in a disconcerted research effort and produces data that are difficult to collate for use in validating the imaging components being studied. Imaging is used in cancer clinical trials for various indications, and the study design needed to evaluate the imaging in a particular indication will vary. Through case examples, this paper will discuss how advanced imaging is currently being investigated in oncology clinical trials, categorized by the potential clinical indication for the imaging tool and offer suggestions on how development should proceed to further evaluate imaging in the given indication. Available National Cancer Institute resources that can assist in this process will also be discussed.

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.

A systematic review and network meta-analysis of neoadjuvant therapy combined with surgery for patients with resectable esophageal squamous cell carcinoma

BACKGROUND

The role of neoadjuvant therapy combined with surgery for treating esophageal squamous cell carcinoma (ESCC) remains controversial. We performed a network meta-analysis to synthesize direct and indirect evidence to identify the optimal therapeutic method for ESCC.

METHODS

We identified 15 randomized controlled trials that compared any of the following 4 therapeutic measures: surgery alone (S), preoperative chemotherapy followed by surgery (CTS), preoperative radiotherapy followed by surgery (RTS), and preoperative chemoradiotherapy followed by surgery (CRTS). The main outcomes were 5-year survival, rate of radical resection, operative mortality and postoperative complications.

RESULTS

Network meta-analysis showed that CRTS was associated with improved survival as compared with S (OR = 1.50 [95% CI 1.21 to 1.97]) and decreased occurrence of complications as compared with RTS (OR = 0.50 [95% CI 0.22 to 0.99]). Direct evidence revealed CRTS associated with improved survival (OR = 1.61 [95% CI 1.01 to 2.57]) and radical resection (OR = 4.01 [95% CI 1.66 to 9.69]) as compared with S. In terms of radical resection, CTS was more effective than S (OR = 1.73 [95% CI 1.09 to 2.76]). Findings for CTS and RTS did not differ for 5-year survival, operative mortality and postoperative complications.

CONCLUSIONS

Overall, CRTS might be the best choice for resectable ESCC because it could increase the radical resection rate and lower the occurrence of complications, thereby prolonging survival time.

Effect of Pathologic Tumor Response and Nodal Status on Survival in the Medical Research Council Adjuvant Gastric Infusional Chemotherapy Trial

PURPOSE

The Medical Research Council Adjuvant Gastric Infusional Chemotherapy (MAGIC) trial established perioperative epirubicin, cisplatin, and fluorouracil chemotherapy as a standard of care for patients with resectable esophagogastric cancer. However, identification of patients at risk for relapse remains challenging. We evaluated whether pathologic response and lymph node status after neoadjuvant chemotherapy are prognostic in patients treated in the MAGIC trial.

MATERIALS AND METHODS

Pathologic regression was assessed in resection specimens by two independent pathologists using the Mandard tumor regression grading system (TRG). Differences in overall survival (OS) according to TRG were assessed using the Kaplan-Meier method and compared using the log-rank test. Univariate and multivariate analyses using the Cox proportional hazards method established the relationships among TRG, clinical-pathologic variables, and OS.

RESULTS

Three hundred thirty resection specimens were analyzed. In chemotherapy-treated patients with a TRG of 1 or 2, median OS was not reached, whereas for patients with a TRG of 3, 4, or 5, median OS was 20.47 months. On univariate analysis, high TRG and lymph node metastases were negatively related to survival (Mandard TRG 3, 4, or 5: hazard ratio [HR], 1.94; 95% CI, 1.11 to 3.39; P = .0209; lymph node metastases: HR, 3.63; 95% CI, 1.88 to 7.0; P < .001). On multivariate analysis, only lymph node status was independently predictive of OS (HR, 3.36; 95% CI, 1.70 to 6.63; P < .001).

CONCLUSION

Lymph node metastases and not pathologic response to chemotherapy was the only independent predictor of survival after chemotherapy plus resection in the MAGIC trial. Prospective evaluation of whether omitting postoperative chemotherapy and/or switching to a noncross-resistant regimen in patients with lymph node-positive disease whose tumor did not respond to preoperative epirubicin, cisplatin, and fluorouracil may be appropriate.

Comparison of characteristics of 18F-fluorodeoxyglucose and 18F-fluorothymidine PET during staging of esophageal squamous cell carcinoma

OBJECTIVES

The aim of this study was to compare the characteristics derived from fluorine-18 fluorodeoxyglucose (F-FDG) and fluorine-18 fluorothymidine (F-FLT) PET quantitatively and to assess their capacities during staging of esophageal squamous cell carcinoma (ESCC).

MATERIALS AND METHODS

Thirty-six patients with a diagnosis of ESCC who underwent both F-FDG and F-FLT PET were included in this study. Different image-derived indices including the standardized uptake value (SUV), gross tumor length, and texture features were determined. Considering histopathologic examination as the gold standard, the performance of the extracted indices during staging of ESCC was assessed using the Kruskal-Wallis test and the Mann-Whitney test.

RESULTS

Considering the F-FDG PET images, the SUVmax, SUVmean, length (LEN), and eccentricity (EC) were significant during staging of American Joint Committee on Cancer (AJCC) and TNM (P<0.01), whereas for the F-FLT image, the SUVmax, LEN, and EC were significant during staging of AJCC and TNM (P<0.01). The characteristics of F-FDG and F-FLT PET for the classification of ESCC stage were significantly different.

CONCLUSION

F-FDG image-derived characteristics including image textural features, SUV, and shape feature allow for better stratification of AJCC and TNM than F-FLT PET in ESCC patients.

Metabolic Imaging to Assess Treatment Response to Cytotoxic and Cytostatic Agents

For several decades, cytotoxic chemotherapeutic agents were considered the basis of anticancer treatment for patients with metastatic tumors. A decrease in tumor burden, assessed by volumetric computed tomography and magnetic resonance imaging, according to the response evaluation criteria in solid tumors (RECIST), was considered as a radiological response to cytotoxic chemotherapies. In addition to RECIST-based dimensional measurements, a metabolic response to cytotoxic drugs can be assessed by positron emission tomography (PET) using (18)F-fluoro-thymidine (FLT) as a radioactive tracer for drug-disrupted DNA synthesis. The decreased (18)FLT-PET uptake is often seen concurrently with increased apparent diffusion coefficients by diffusion-weighted imaging due to chemotherapy-induced changes in tumor cellularity. Recently, the discovery of molecular origins of tumorogenesis led to the introduction of novel signal transduction inhibitors (STIs). STIs are targeted cytostatic agents; their effect is based on a specific biological inhibition with no immediate cell death. As such, tumor size is not anymore a sensitive end point for a treatment response to STIs; novel physiological imaging end points are desirable. For receptor tyrosine kinase inhibitors as well as modulators of the downstream signaling pathways, an almost immediate inhibition in glycolytic activity (the Warburg effect) and phospholipid turnover (the Kennedy pathway) has been seen by metabolic imaging in the first 24 h of treatment. The quantitative imaging end points by magnetic resonance spectroscopy and metabolic PET (including 18F-fluoro-deoxy-glucose, FDG, and total choline) provide an early treatment response to targeted STIs, before a reduction in tumor burden can be seen.

Computerized PET/CT image analysis in the evaluation of tumour response to therapy

Current cancer therapy strategy is mostly population based, however, there are large differences in tumour response among patients. It is therefore important for treating physicians to know individual tumour response. In recent years, many studies proposed the use of computerized positron emission tomography/CT image analysis in the evaluation of tumour response. Results showed that computerized analysis overcame some major limitations of current qualitative and semiquantitative analysis and led to improved accuracy. In this review, we summarize these studies in four steps of the analysis: image registration, tumour segmentation, image feature extraction and response evaluation. Future works are proposed and challenges described.

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.

Adjuvant or neoadjuvant therapy for operable esophagogastric cancer?

Esophagogastric cancer encompasses proximal squamous cell carcinoma of the esophagus, distal esophageal/junctional adenocarcinoma of the esophagus and gastric adenocarcinoma. These diseases have different etiologies, geographic incidences and biologies. This review mainly focuses on the treatment of operable esophagogastric adenocarcinoma. In Asia, adjuvant chemotherapy is commonly used for patients with gastric cancer following the landmark ACTS-GC trial. In contrast, perioperative chemotherapy is a standard of care in many Western countries based on the results of the MAGIC trial. Neoadjuvant chemotherapy is better tolerated than adjuvant therapy, and therefore dose intensity is likely to be maintained in a greater proportion of patients. In addition, neoadjuvant treatment can lead to tumor downstaging, increasing the likelihood of achieving a complete surgical resection. This may be particularly important in Western populations, as these patients often present with more advanced tumors than Asian patients. Adjuvant chemoradiotherapy is a standard treatment option in the USA for adenocarcinoma of the stomach or gastroesophageal junction as a result of the INT-0116 trial, but the benefit of this approach after a D2 resection has not been confirmed. Neoadjuvant chemoradiotherapy may reduce the risk of local recurrence and may be particularly beneficial for patients with squamous cell carcinoma as these tumors are more radiosensitive. However, patients with esophagogastric adenocarcinoma are more likely to relapse with distant disease, and therefore a systemic disease approach with chemotherapy is likely to be more beneficial than a purely localized treatment strategy for these patients.

Positron Emission Tomography (PET) in Oncology

Since its introduction in the early nineties as a promising functional imaging technique in the management of neoplastic disorders, FDG-PET, and subsequently FDG-PET/CT, has become a cornerstone in several oncologic procedures such as tumor staging and restaging, treatment efficacy assessment during or after treatment end and radiotherapy planning. Moreover, the continuous technological progress of image generation and the introduction of sophisticated software to use PET scan as a biomarker paved the way to calculate new prognostic markers such as the metabolic tumor volume (MTV) and the total amount of tumor glycolysis (TLG). FDG-PET/CT proved more sensitive than contrast-enhanced CT scan in staging of several type of lymphoma or in detecting widespread tumor dissemination in several solid cancers, such as breast, lung, colon, ovary and head and neck carcinoma. As a consequence the stage of patients was upgraded, with a change of treatment in 10%-15% of them. One of the most evident advantages of FDG-PET was its ability to detect, very early during treatment, significant changes in glucose metabolism or even complete shutoff of the neoplastic cell metabolism as a surrogate of tumor chemosensitivity assessment. This could enable clinicians to detect much earlier the effectiveness of a given antineoplastic treatment, as compared to the traditional radiological detection of tumor shrinkage, which usually takes time and occurs much later.

PET/CT imaging in cancer: current applications and future directions

Positron emission tomography (PET) is a radiotracer imaging method that yields quantitative images of regional in vivo biology and biochemistry. PET, now used in conjunction with computed tomography (CT) in PET/CT devices, has had its greatest impact to date on cancer and is now an important part of oncologic clinical practice and translational cancer research. In this review of current applications and future directions for PET/CT in cancer, the authors first highlight the basic principles of PET followed by a discussion of the biochemistry and current clinical applications of the most commonly used PET imaging agent, (18) F-fluorodeoxyglucose (FDG). Then, emerging methods for PET imaging of other biologic processes relevant to cancer are reviewed, including cellular proliferation, tumor hypoxia, apoptosis, amino acid and cell membrane metabolism, and imaging of tumor receptors and other tumor-specific gene products. The focus of the review is on methods in current clinical practice as well as those that have been translated to patients and are currently in clinical trials.

A systematic review of the predictive value of (18)FDG-PET in esophageal and esophagogastric junction cancer after neoadjuvant chemoradiation on the survival outcome stratification

PURPOSE

We studied the predictive value of [(18) F]fluorodeoxyglucose-positron emission tomography ((18)FDG-PET) for assessing disease-free (DFS) and overall survival (OS) in esophageal and esophagogastric junction cancer.

MATERIALS AND METHODS

A literature search (PUBMED/MEDLINE, EMBASE, Cochrane) was performed to identify full papers with (18)FDG-PET and survival data, using indexing terms and free text words. Studies with >10 patients with locally advanced esophageal cancer, presenting sequential or at least one post-adjuvant treatment (18)FDG-PET data and Kaplan-Meier survival curves with >6 months median follow-up period were included. We performed a meta-analysis for DFS and OS using the hazard ratio (HRs) as outcome measure. Sources of heterogeneity study were also explored.

RESULTS

We identified 26 eligible studies including a total of 1,544 patients (average age 62 years, 82% males). The TNM distribution was as follows: stage I 7%, II 24%, III 53% and IV 15%. The pooled HRs for complete metabolic response versus no response were 0.51 for OS (95% CI, 0.4-0.64; P < 0.00001) and 0.47 for DFS (95% CI, 0.38-0.57; P < 0.00001), respectively. No statistical heterogeneity was present. To explore sources of clinical heterogeneity, we also realised subgroup and regression analyses. Taken into account the moderate correlation between OS and DFS (ρ = 0.54), we used joint bivariate random regression model. These analyses did not show a statistically significant impact of study characteristics and PET modalities on the pooled outcome estimates.

CONCLUSION

Despite methodological and clinical heterogeneity, metabolic response on (18)FDG-PET is a significant predictor of long-term survival data.

Monitoring tumour response during chemo-radiotherapy: a parametric method using FDG-PET/CT images in patients with oesophageal cancer

Background

The objective of this study is to investigate the feasibility and the additional interest of a parametric imaging (PI) method to monitor the early tumour metabolic response in a prospective series of oesophageal cancer patients who underwent positron emission tomography with fluoro-2-deoxy-d-glucose (FDG-PET/CT) before and during curative-intent chemo-radiotherapy.

Methods

Fifty-seven patients with squamous cell carcinoma (SCC) of the oesophagus prospectively underwent FDG-PET/CT before chemo-radiotherapy (CRT) (PET₁) and at 21 ± 3 days after the beginning of CRT (PET₂). The outcome was assessed at 3 months and 1 year after the completion of CRT (clinical examination, CT scan or FDG-PET/CT, biopsy). For each patient, PET₁ and PET₂ were registered using CT images. The 2 PET image sets were subtracted, so the voxels with significant changes in FDG uptake were identified. A model-based analysis of this graph was used to identify the tumour voxels in which significant changes occurred between the two scans and yielded indices characterising these changes (green and red clusters). Quantitative parameters were compared with clinical outcome at 3 months and at 1 year.

Results

The baseline tumour FDG uptake decreased significantly at PET₂ (p < 0.0001). The tumour volume significantly decreased between PET₁ and PET₂ (p < 0.02). The initial functional volume of the lesion (TV₁) was significantly lower (p < 0.02) in patients in clinical response (CR) at 3 months and 1 year. The volume of the lesion during the treatment (TV₂) was significantly lower in patients identified as in CR at 3 months (p < 0.03), but did not predict the outcome at 1 year. Multivariate analyses of outcome at 3 months showed that the risk of failure/death increased with younger age (p = 0.001), larger metabolic volume on PET₁ (p = 0.009) and larger volume with decreased FDG uptake (p = 0.047). As for outcome at 1 year, the risk of failure/death increased with younger age (p = 0.006), nodal involvement (p = 0.08) and larger volumes with increased uptake (p = 0.03).

Conclusion

A parametric method to assess tumour response on serial FDG-PET performed during chemo-radiotherapy was evaluated. Early metabolic changes, i.e. variations in FDG uptake, provided additional prognostic information in multivariate analyses ClinicalTrials.gov NCT 00934505.

Trial registration

Current Controlled Trials ISRCTN7824458

Multimodality imaging to assess immediate response to irreversible electroporation in a rat liver tumor model

PURPOSE

To compare changes on ultrasonographic (US), computed tomographic (CT), and magnetic resonance (MR) images after irreversible electroporation (IRE) ablation of liver and tumor tissues in a rodent hepatoma model.

MATERIALS AND METHODS

Studies received approval from the institutional animal care and use committee. Forty-eight rats were used, and N1-S1 tumors were implanted in 24. Rats were divided into groups and allocated for studies with each modality. Imaging was performed in normal liver tissues and tumors before and after IRE. MR imaging was performed in one group before and after IRE after hepatic vessel ligation. US images were graded to determine echogenicity changes, CT attenuation was measured (in Hounsfield units), and MR imaging signal-to-noise ratio (SNR) was measured before and after IRE. Student t test was used to compare attenuation and SNR measurements before and after IRE (P < .05 indicated a significant difference).

RESULTS

IRE ablation produced greater alterations to echogenicity in normal tissues than in tumors. Attenuation in ablated liver tissues was reduced compared with that in control tissues (P < .001), while small attenuation differences between ablated (42.11 HU ± 2.11) and control (45.14 HU ± 2.64) tumors trended toward significance (P = .052). SNR in ablated normal tissues was significantly altered after IRE (T1-weighted images: pre-IRE, 145.95 ± 24.32; post-IRE, 97.80 ± 18.03; P = .004; T2-weighted images, pre-IRE, 47.37 ± 18.31; post-IRE, 90.88 ± 37.15; P = .023). In tumors, SNR differences before and after IRE were not significant. No post-IRE signal changes were observed after hepatic vessel ligation.

CONCLUSION

IRE induces rapid changes on gray-scale US, unenhanced CT, and MR images. These changes are readily visible and may assist a performing physician to delineate ablation zones from the unablated surrounding parenchyma.

Modeling pathologic response of esophageal cancer to chemoradiation therapy using spatial-temporal 18F-FDG PET features, clinical parameters, and demographics

PURPOSE

To construct predictive models using comprehensive tumor features for the evaluation of tumor response to neoadjuvant chemoradiation therapy (CRT) in patients with esophageal cancer.

METHODS AND MATERIALS

This study included 20 patients who underwent trimodality therapy (CRT+surgery) and underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) both before and after CRT. Four groups of tumor features were examined: (1) conventional PET/CT response measures (eg, standardized uptake value [SUV]max, tumor diameter); (2) clinical parameters (eg, TNM stage, histology) and demographics; (3) spatial-temporal PET features, which characterize tumor SUV intensity distribution, spatial patterns, geometry, and associated changes resulting from CRT; and (4) all features combined. An optimal feature set was identified with recursive feature selection and cross-validations. Support vector machine (SVM) and logistic regression (LR) models were constructed for prediction of pathologic tumor response to CRT, cross-validations being used to avoid model overfitting. Prediction accuracy was assessed by area under the receiver operating characteristic curve (AUC), and precision was evaluated by confidence intervals (CIs) of AUC.

RESULTS

When applied to the 4 groups of tumor features, the LR model achieved AUCs (95% CI) of 0.57 (0.10), 0.73 (0.07), 0.90 (0.06), and 0.90 (0.06). The SVM model achieved AUCs (95% CI) of 0.56 (0.07), 0.60 (0.06), 0.94 (0.02), and 1.00 (no misclassifications). With the use of spatial-temporal PET features combined with conventional PET/CT measures and clinical parameters, the SVM model achieved very high accuracy (AUC 1.00) and precision (no misclassifications)-results that were significantly better than when conventional PET/CT measures or clinical parameters and demographics alone were used. For groups with many tumor features (groups 3 and 4), the SVM model achieved significantly higher accuracy than did the LR model.

CONCLUSIONS

The SVM model that used all features including spatial-temporal PET features accurately and precisely predicted pathologic tumor response to CRT in esophageal cancer.

Role of positron emission tomography-computed tomography in gastrointestinal malignancies

Positron emission tomography (PET) has proved itself to be valuable in the evaluation of patients with a wide array of gastrointestinal (GI) malignancies. Subsequent development of fusion imaging with PET and computed tomography (PET-CT) scanners has significantly advanced the capabilities of imaging by combining the functional data of the(18)F-labeled glucose analogue fluorodeoxyglucose (FDG) with the conventional anatomic data provided by CT. This article reviews the evolving role of FDG PET-CT imaging in the initial assessment and monitoring of GI tumors. Specific applications are discussed, and normal variants and benign findings frequently encountered during PET-CT of the GI tract are reviewed.

New PET/CT Features for the Evaluation of Tumor Response

With the emerging multi-modality imaging performed at multiple time points for each patient, it becomes more important to analyze the serial images quantitatively, select and combine both complementary and contradictory information from various sources, for accurate and personalized evaluation of tumor response to therapy.

The predictive value of treatment response using FDG PET performed on day 21 of chemoradiotherapy in patients with oesophageal squamous cell carcinoma. A prospective, multicentre study (RTEP3)

PURPOSE

FDG PET has been suggested to have predictive value in the prognosis of oesophageal carcinoma. However, the retrospective studies reported in the literature have shown discordant results. Additionally, only four studies have evaluated FDG PET during chemoradiotherapy (CRT) in patients with different histological lesions. The purpose of this study was to investigate the predictive value of FDG PET performed early during CRT (on day 21) in a population of patients with oesophageal squamous cell carcinoma.

METHODS

Included in this prospective study were 57 patients with a histological diagnosis of squamous cell carcinoma of the oesophagus. Of these 57 patients, 48 (84%) were evaluated (aged 63 ± 11 years; 44 men, 4 women). Each patient underwent FDG PET (4.5 MBq/kg) before CRT, according to the Herskovic protocol (t0; PET₁) and on day 21 ± 3 from the start of CRT (d21; PET₂). The response assessment included a clinical examination, CT scan or FDG PET and histological analysis 3 months and 1 year after PET₁. The patients were classified as showing a complete response (CR) or a noncomplete response. A quantitative analysis was carried out for PET₁ and PET₂ using the following parameters: SUVmax, SUVmean (with SUVmean40 as the 3-D volume at an SUVmax threshold of 40% and SUVmeanp as that defined by a physician), tumour volume (TV, with TV40 defined as the TV at 40% of SUVmax, and TVp as that defined by a physician); and the total lesion glycolysis (TLG, SUVmean × TV, with TLG₄₀ defined as the TLG at 40% of SUVmax, and TLGp as that defined by a physician). The differences in responses at 3 months and 1 year between PET₁ (t0) and PET₂ (d21) were assessed in terms of variations in SUV, TV and TLG using a repeated measures of variance (ANOVA).

RESULTS

SUVmax, SUVmean and TLG decreased significantly between PET₁ (t0) and PET₂ (d21; p < 0.0001). The TV significantly decreased only when assessed as TVp (p = 0.02); TV₄₀ did not decrease significantly. With respect to the predictive value of PET₁, only TV40_1 and TVp_1 values, and therefore TLG40_1 and TLGp_1, but not the SUV values, were significantly lower in patients with CR at 3 months. SUVmax1, TVp_1 and TLGp_1 were significantly lower in patients with CR at 1 year. With respect to the predictive value of PET₂, only TV40_2 and TVp_2 values, and therefore TLG40_2 and TLGp_2, but not the SUV values, were significantly lower in patients with CR at 3 months. None of the PET₂ parameters had significant value in predicting patient outcome at 1 year. The changes in SUVmax, TV₄₀, TVp, TLG₄₀ and TLGp between PET₁ and PET₂ had no relationship to patient outcome at 3 months or 1 year.

CONCLUSION

This prospective, multicentre study performed in a selected population of patients with oesophageal squamous cell cancer demonstrates that the parameters derived from baseline PET₁ are good predictors of response to CRT. Specifically, a high TV and TLG are associated with a poor response to CRT at 3 months and 1 year, and a high SUVmax is associated with a poor response to CRT at 1 year. FDG PET performed during CRT on day 21 appears to have less clinical relevance. However, patients with a large functional TV on day 21 of CRT have a poor clinical outcome (ClinicalTrials.gov NCT 00934505).

Present status and progress of neoadjuvant chemoradiotherapy for esophageal cancer

Trimodality based on neoadjuvant chemoradiotherapy (nCRT) followed by surgery is gaining popularity as a treatment strategy for locally advanced esophageal cancer. In this review, we summarize the role of nCRT and the recommended nCRT regimens based on clinical trials and meta-analyses. We analyze the relationship of nCRT with pathologic complete response (pCR) and then identify potential predictive markers of response. Compared with surgery alone and neoadjuvant chemotherapy followed by surgery, trimodality provides longer survival and has the advantage of local control compared with definitive chemoradiotherapy. The standard regimen is a platinum-based regimen with a radiation dose range of 41.4-50.4 Gy by conventional fractionation. Evidence shows that patients with pCR tend to live longer than non-responders, indicating that pCR is a significant prognostic factor for patients with esophageal cancer. Individualized medicine requires predictive markers of individual patients based on their own genes. Currently, no definite marker is proved to be sufficiently sensitive and specific for use in clinical practice, although 18-fluorodeoxyglucose positron emission tomography shows promise in predicting response to nCRT.

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.

Impact of patient selection, disease progression, and adverse events on esophageal cancer outcomes after trimodality therapy

BACKGROUND

Neoadjuvant chemoradiation followed by surgery (NeoCRT) has been advocated as standard therapy for resectable esophageal cancer. Our objective was to compare oncologic outcomes between NeoCRT and upfront surgical resection (SURG).

METHODS

We conducted a single-institution, retrospective review of all potentially resectable esophageal cancer patients treated with NeoCRT or SURG.

RESULTS

From 2003 to 2010, 151 patients had NeoCRT (n = 48; 31.8%) or SURG (n = 103; 68.1%). Histology was mostly adenocarcinoma (77.5%) or squamous carcinoma (19.2%). Mean radiation dose was 44 ± 0.1 Gy, and 80.8% received platinum-based doublet chemotherapy. There were more women in the SURG group (23.3% vs 4.2%; p < 0.01) and more cardiovascular comorbidity in the NeoCRT group (39.6% vs 21.4%; p = 0.027). There was no difference in age, histology, R0 resection rate, and treatment-related mortality (NeoCRT = 4.2%; SURG = 3.9%; p = 0.15). Failure to undergo resection after NeoCRT (n = 11; 22.9%) was mainly due to disease progression (n = 6) or treatment-related mortality (n = 4). Resection could not be performed in 4 SURG patients (3.9%; p < 0.001; unresectable = 2; occult metastases = 2). NeoCRT did not improve median survival (NeoCRT = 29 ± 6; SURG = 26 ± 3 months; p = 0.376) or recurrence-free interval (NeoCRT = 25.8 ± 5; SURG = 19.4 ± 2 months; p = 0.19). Complete pathologic response (n = 8; 21.6%) was not associated with improved survival. If we exclude from analysis NeoCRT patients who did not undergo surgery, survival was significantly improved after NeoCRT (NeoCRT = 41 ± 15; SURG = 24 ± 8 months; p = 0.0082).

CONCLUSIONS

Patient selection and early assessment of treatment response may be key factors in identifying the best candidates for trimodality therapy.

PET imaging: implications for the future of therapy monitoring with PET/CT in oncology

Among the methods based on molecular imaging, the measure of the tracer uptake variation between a baseline and follow-up scan with the SUV and [(18)F]FDG-PET/CT is a very powerful tool for assessing response to treatment in oncology. However, the development of new targeted therapeutics and tissue pharmacokinetic evaluation of existing ones are increasingly requiring therapy monitoring with alternative tracers and indicators. In parallel, the potential predictive and prognostic value of other image-derived parameters, such as tumour volume and textural features, relating to tumoral heterogeneity, has recently emerged from several works.

Repeatability of 18F-FDG uptake measurements in tumors: a metaanalysis

PET with the glucose analog (18)F-FDG is increasingly used to monitor tumor response to therapy. To use quantitative measurements of tumor (18)F-FDG uptake for assessment of tumor response, the repeatability of this quantitative metabolic imaging method needs to be established. Therefore, we determined the repeatability of different standardized uptake value (SUV) measurements using the available data.

METHODS

A systematic literature search was performed to identify studies addressing (18)F-FDG repeatability in malignant tumors. The level of agreement between test and retest values of 2 PET uptake measures, maximum SUV (SUV(max)) and mean SUV (SUV(mean)), was assessed with the coefficient of repeatability using generalized linear mixed-effects models. In addition, the influence of tumor volume on repeatability was assessed. Principal component transformation was used to compare the reproducibility of the 2 different uptake measures.

RESULTS

Five cohorts were identified for this metaanalysis. For SUV(max) and SUV(mean), datasets of 86 and 102 patients, respectively, were available. Percentage repeatability is a function of the level of uptake. SUV(mean) had the best repeatability characteristics; for serial PET scans, a threshold of a combination of 20% as well as 1.2 SUV(mean) units was most appropriate. After adjusting for uptake rate, tumor volume had minimal influence on repeatability.

CONCLUSION

SUV(mean) had better repeatability performance than SUV(max). Both measures showed poor repeatability for lesions with low (18)F-FDG uptake. We recommend the evaluation of biologic effects in PET by reporting a combination of minimal relative and absolute changes to account for test-retest variability.

Comparative study between endoscopic ultrasonography and positron emission tomography-computed tomography in staging patients with esophageal squamous cell carcinoma

Treatment strategy of esophageal cancer mainly depends on accurate staging. At present, no single ideal staging modality is superior to another in preoperative tumor-node-metastasis (TNM) staging of patients with esophageal cancer. We aimed to investigate the efficacy of endoscopic ultrasonography (EUS) and positron emission tomography-computed tomography (PET-CT) for staging of esophageal cancer. We retrospectively studied 118 consecutive patients with esophageal squamous cell carcinoma who underwent esophagectomy with or without neoadjuvant chemoradiotherapy (CRT) over a near 3-year period between January 2005 and November 2008 at a tertiary hospital in Taiwan. Patients were separated into two groups: without neoadjuvant CRT (group 1, n= 28) and with CRT (group 2, n= 90). Medical records of demographic data and reports of EUS and PET-CT of patients before surgery were reviewed. A database of clinical staging by EUS and PET-CT was compared with one of pathological staging. The accuracies of T staging by EUS in groups 1 and 2 were 85.2% and 34.9%. The accuracies of N staging by EUS in groups 1 and 2 were 55.6% and 39.8%. The accuracies of T and N staging by means of PET-CT scan were 100% and 54.5% in group 1, and were 69.4% and 86.1% in group 2, respectively. In group 2, 38 of 90 patients (42.2%) achieved pathologic complete remission. Among them, two of 34 (5.9%) and 12 of 17 (70.6%) patients were identified as tumor-free by post-CRT EUS and PET-CT, respectively. EUS is useful for initial staging of esophageal cancer. PET-CT is a more reliable modality for monitoring treatment response and restaging. Furthermore, the accuracy of PET-CT with regard to N staging is higher in patients who have undergone CRT than those who have not.

Curative treatment of oesophageal carcinoma: current options and future developments

Since the 1980s major advances in surgery, radiotherapy and chemotherapy have established multimodal approaches as curative treatment options for oesophageal cancer. In addition the introduction of functional imaging modalities such as PET-CT created new opportunities for a more adequate patient selection and therapy response assessment.

The majority of oesophageal carcinomas are represented by two histologies: squamous cell carcinoma and adenocarcinoma. In recent years an epidemiological shift towards the latter was observed. From a surgical point of view, adenocarcinomas, which are usually located in the distal third of the oesophagus, may be treated with a transhiatal resection, whereas squamous cell carcinomas, which are typically found in the middle and the upper third, require a transthoracic approach. Since overall survival after surgery alone is poor, multimodality approaches have been developed. At least for patients with locally advanced tumors, surgery alone can no longer be advocated as routine treatment. Nowadays, scientific interest is focused on tumor response to induction radiochemotherapy. A neoadjuvant approach includes the early and accurate assessment of clinical response, optimally performed by repeated PET-CT imaging and endoscopic ultrasound, which may permit early adaption of the therapeutic concept. Patients with SCC that show clinical response by PET CT are considered to have a better prognosis, regardless of whether surgery will be performed or not. In non-responding patients salvage surgery improves survival, especially if complete resection is achieved.

Baseline ¹⁸F-FDG PET image-derived parameters for therapy response prediction in oesophageal cancer

PURPOSE

The objectives of this study were to investigate the predictive value of tumour measurements on 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) positron emission tomography (PET) pretreatment scan regarding therapy response in oesophageal cancer and to evaluate the impact of tumour delineation strategies.

METHODS

Fifty patients with oesophageal cancer treated with concomitant radiochemotherapy between 2004 and 2008 were retrospectively considered and classified as complete, partial or non-responders (including stable and progressive disease) according to Response Evaluation Criteria in Solid Tumors (RECIST). The classification of partial and complete responders was confirmed by biopsy. Tumours were delineated on the (18)F-FDG pretreatment scan using an adaptive threshold and the automatic fuzzy locally adaptive Bayesian (FLAB) methodologies. Several parameters were then extracted: maximum and peak standardized uptake value (SUV), tumour longitudinal length (TL) and volume (TV), SUV(mean), and total lesion glycolysis (TLG = TV × SUV(mean)). The correlation between each parameter and response was investigated using Kruskal-Wallis tests, and receiver-operating characteristic methodology was used to assess performance of the parameters to differentiate patients.

RESULTS

Whereas commonly used parameters such as SUV measurements were not significant predictive factors of the response, parameters related to tumour functional spatial extent (TL, TV, TLG) allowed significant differentiation of all three groups of patients, independently of the delineation strategy, and could identify complete and non-responders with sensitivity above 75% and specificity above 85%. A systematic although not statistically significant trend was observed regarding the hierarchy of the delineation methodologies and the parameters considered, with slightly higher predictive value obtained with FLAB over adaptive thresholding, and TLG over TV and TL.

CONCLUSION

TLG is a promising predictive factor of concomitant radiochemotherapy response with statistically higher predictive value than SUV measurements in advanced oesophageal cancer.

Metabolic positron emission tomography imaging in cancer detection and therapy response

Positron emission tomography (PET) is a noninvasive imaging technique that provides a functional or metabolic assessment of normal tissue or disease conditions. Fluorine 18-fluorodeoxyglucose PET imaging (FDG-PET) is widely used clinically for tumor imaging due to increased glucose metabolism in most types of tumors, and has been shown to improve the diagnosis and subsequent treatment of cancers. We review its use in cancer diagnosis, staging, restaging, and assessment of response to treatment. In addition, other metabolic PET imaging agents in pre-clinical research or clinical trial stages of development are discussed, including amino acid analogs based on increased protein synthesis, and choline, which is based on increased membrane lipid synthesis. Amino acid analogs and choline are more specific to tumor cells than FDG, so they play an important role in differentiating cancers from benign conditions and in the diagnosis of cancers with low FDG uptake or high background FDG uptake. For decades, researchers have shown that tumors display altered metabolic profiles with elevated uptake of glucose, amino acids, and lipids. This can be used for cancer diagnosis and monitoring of the therapeutic response with excellent signal-to-noise ratios.

Meta-analysis of neoadjuvant treatment modalities and definitive non-surgical therapy for oesophageal squamous cell cancer

BACKGROUND

The standard treatment for resectable oesophageal squamous cell carcinoma (OSCC) is surgical resection with adequate lymphadenectomy. Most Western patients receive neoadjuvant chemotherapy or chemoradiotherapy (CRT). In recent years some patients have received CRT alone (definitive CRT, dCRT). This meta-analysis sought to clarify the benefits of neoadjuvant and definitive treatment for OSCC.

METHODS

Eligible randomized controlled trials (RCTs) were identified using the Cochrane database, MEDLINE and Embase. Only RCTs with intention-to-treat analysis, and published hazard ratios (HRs) or estimates from survival data, were included.

RESULTS

Nine RCTs involving neoadjuvant CRT versus surgery, eight involving neoadjuvant chemotherapy versus surgery, and three involving neoadjuvant treatment followed by surgery or surgery alone versus dCRT were identified. The HR for overall survival was 0·81 (95 per cent confidence interval 0·70 to 0·95; P = 0·008) after neoadjuvant CRT and 0·93 (0·81 to 1·08; P = 0·368) after neoadjuvant chemotherapy. The likelihood of R0 resection was significantly higher after neoadjuvant treatment (CRT: HR 1·15, P = 0·043; chemotherapy: HR 1·16, P = 0·006). Morbidity rates were not increased after neoadjuvant CRT (HR 0·94, P = 0·363) but 30-day mortality was non-significantly higher with combined treatment. Morbidity (HR 1·03, P = 0·638) and mortality (HR 1·04, P = 0·810) rates after neoadjuvant chemotherapy and surgery did not differ from those after surgery alone. None of the RCTs reporting outcome after dCRT demonstrated a significant survival benefit, but treatment-related mortality rates were lower (HR 7·60, P = 0·007) than with neoadjuvant treatment followed by surgery or surgery alone.

CONCLUSION

For patients with resectable OSCC, a significant survival benefit for neoadjuvant CRT was evident, with no increase in morbidity rate. dCRT did not demonstrate any survival benefit over other curative strategies. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.

Current status of methods to assess cancer drug resistance

Drug resistance is the main cause of the failure of chemotherapy of malignant tumors, resistance being either preexisting (intrinsic resistance) or induced by the drugs (acquired resistance). At present, resistance is usually diagnosed during treatment after a long period of drug administration.In the present paper, methods for a rapid assessment of drug resistance are described. Three main classes of test procedures can be found in the literature, i.e. fresh tumor cell culture tests, cancer biomarker tests and positron emission tomography (PET) tests. The methods are based on the evaluation of molecular processes, i.e. metabolic activities of cancer cells. Drug resistance can be diagnosed before treatment in-vitro with fresh tumor cell culture tests, and after a short time of treatment in-vivo with PET tests. Cancer biomarker tests, for which great potential has been predicted, are largely still in the development stage. Individual resistance surveillance with tests delivering rapid results signifies progress in cancer therapy management, by providing the possibility to avoid drug therapies that are ineffective and only harmful.

Intratumor heterogeneity characterized by textural features on baseline 18F-FDG PET images predicts response to concomitant radiochemotherapy in esophageal cancer

(18)F-FDG PET is often used in clinical routine for diagnosis, staging, and response to therapy assessment or prediction. The standardized uptake value (SUV) in the primary or regional area is the most common quantitative measurement derived from PET images used for those purposes. The aim of this study was to propose and evaluate new parameters obtained by textural analysis of baseline PET scans for the prediction of therapy response in esophageal cancer.

METHODS

Forty-one patients with newly diagnosed esophageal cancer treated with combined radiochemotherapy were included in this study. All patients underwent pretreatment whole-body (18)F-FDG PET. Patients were treated with radiotherapy and alkylatinlike agents (5-fluorouracil-cisplatin or 5-fluorouracil-carboplatin). Patients were classified as nonresponders (progressive or stable disease), partial responders, or complete responders according to the Response Evaluation Criteria in Solid Tumors. Different image-derived indices obtained from the pretreatment PET tumor images were considered. These included usual indices such as maximum SUV, peak SUV, and mean SUV and a total of 38 features (such as entropy, size, and magnitude of local and global heterogeneous and homogeneous tumor regions) extracted from the 5 different textures considered. The capacity of each parameter to classify patients with respect to response to therapy was assessed using the Kruskal-Wallis test (P < 0.05). Specificity and sensitivity (including 95% confidence intervals) for each of the studied parameters were derived using receiver-operating-characteristic curves.

RESULTS

Relationships between pairs of voxels, characterizing local tumor metabolic nonuniformities, were able to significantly differentiate all 3 patient groups (P < 0.0006). Regional measures of tumor characteristics, such as size of nonuniform metabolic regions and corresponding intensity nonuniformities within these regions, were also significant factors for prediction of response to therapy (P = 0.0002). Receiver-operating-characteristic curve analysis showed that tumor textural analysis can provide nonresponder, partial-responder, and complete-responder patient identification with higher sensitivity (76%-92%) than any SUV measurement.

CONCLUSION

Textural features of tumor metabolic distribution extracted from baseline (18)F-FDG PET images allow for the best stratification of esophageal carcinoma patients in the context of therapy-response prediction.