Prognostic value of gross tumor volume delineated by FDG-PET-CT based radiotherapy treatment planning in patients with locally advanced pancreatic cancer treated with chemoradiotherapy

The Significance of FDG PET/CT-Derived Parameters in Determining Prognosis of Cases with Pancreatic Adenocarcinoma: A Prospective Study

Background and objectives: Pancreatic adenocarcinoma represents one of the common malignancies with a relatively poor prognosis. However, early detection of this type of cancer may prove to be curable. Recent advancements in the radiological techniques might represent a hope for the early diagnosis and prediction of prognosis of pancreatic adenocarcinoma. This study aimed to assess the prognostic value of the primary tumor volumetric parameters obtained from FDG PET/CT first stage for the overall survival (OS) and progression-free survival (PFS) of patients with pancreatic adenocarcinoma and to explore the possible correlation between serum matrix metalloproteinase-2 (MMP-2) and the patients’ characteristics. Methods: Fifty patients with pancreatic adenocarcinoma were subjected to FDG PET/CT scan. The SUVpeak, SUVmax, and the metabolic tumor volume (MTV) were determined, as well as the SUVmean of the liver. Moreover, serum levels of MMP-2 were assessed. Follow-up of the patients was carried out for sixty months with determination of PFS and OS. Results: Peak SUV ≥ 3.9 was significantly correlated with the primary pancreatic lesions’ mean total glycolytic activity of >92 g, and MTV and was directly correlated with mortality. There was a positive correlation between peak SUV ≥ 3.9 and 50% SUVmax threshold > 82. Moreover, there was significant correlation between the total glycolytic activity and the studied clinicopathologic factors, except the age and sex of the patients and ECOG performance status. In addition, FDG uptake and the tumor glycolytic activity were substantially linked with a shorter PFS. Similarly, a strong correlation was found between MTV and PFS. Serum MMP-2 levels showed a significant relationship with the performance status, tumor stage, SUVmax threshold, and the glycolytic activity. Conclusions: Peak SUV, main lesion SUVmax, serum MMP-2, and the tumor glycolytic activity are good predictors of PFS of patients with pancreatic adenocarcinoma.

Quality gaps in public pancreas imaging datasets: Implications & challenges for AI applications

OBJECTIVE

Quality gaps in medical imaging datasets lead to profound errors in experiments. Our objective was to characterize such quality gaps in public pancreas imaging datasets (PPIDs), to evaluate their impact on previously published studies, and to provide post-hoc labels and segmentations as a value-add for these PPIDs.

METHODS

We scored the available PPIDs on the medical imaging data readiness (MIDaR) scale, and evaluated for associated metadata, image quality, acquisition phase, etiology of pancreas lesion, sources of confounders, and biases. Studies utilizing these PPIDs were evaluated for awareness of and any impact of quality gaps on their results. Volumetric pancreatic adenocarcinoma (PDA) segmentations were performed for non-annotated CTs by a junior radiologist (R1) and reviewed by a senior radiologist (R3).

RESULTS

We found three PPIDs with 560 CTs and six MRIs. NIH dataset of normal pancreas CTs (PCT) (n = 80 CTs) had optimal image quality and met MIDaR A criteria but parts of pancreas have been excluded in the provided segmentations. TCIA-PDA (n = 60 CTs; 6 MRIs) and MSD(n = 420 CTs) datasets categorized to MIDaR B due to incomplete annotations, limited metadata, and insufficient documentation. Substantial proportion of CTs from TCIA-PDA and MSD datasets were found unsuitable for AI due to biliary stents [TCIA-PDA:10 (17%); MSD:112 (27%)] or other factors (non-portal venous phase, suboptimal image quality, non-PDA etiology, or post-treatment status) [TCIA-PDA:5 (8.5%); MSD:156 (37.1%)]. These quality gaps were not accounted for in any of the 25 studies that have used these PPIDs (NIH-PCT:20; MSD:1; both: 4). PDA segmentations were done by R1 in 91 eligible CTs (TCIA-PDA:42; MSD:49). Of these, corrections were made by R3 in 16 CTs (18%) (TCIA-PDA:4; MSD:12) [mean (standard deviation) Dice: 0.72(0.21) and 0.63(0.23) respectively].

CONCLUSION

Substantial quality gaps, sources of bias, and high proportion of CTs unsuitable for AI characterize the available limited PPIDs. Published studies on these PPIDs do not account for these quality gaps. We complement these PPIDs through post-hoc labels and segmentations for public release on the TCIA portal. Collaborative efforts leading to large, well-curated PPIDs supported by adequate documentation are critically needed to translate the promise of AI to clinical practice.

Clinical Impact of 18F-FDG PET/CT in the Diagnostic Workup of Pancreatic Ductal Adenocarcinoma: A Systematic Review

In this review, the performance of fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) in the diagnostic workup of pancreatic ductal adenocarcinoma (PDAC) is evaluated. A comprehensive literature search up to September 2020 was performed, selecting studies with the presence of: sample size ≥10 patients and index test (i.e., “FDG” or “18F-FDG” AND “pancreatic adenocarcinoma” or “pancreas cancer” AND “PET” or “positron emission tomography”). The methodological quality was evaluated using the revised quality assessment of diagnostic accuracy studies (QUADAS-2) tool and presented according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Basic data (authors, year of publication, country and study design), patients’ characteristics (number of enrolled subjects and age), disease phase, type of treatment and grading were retrieved. Forty-six articles met the adopted research criteria. The articles were divided according to the considered clinical context. Namely, besides conventional anatomical imaging, such as computed tomography (CT) and magnetic resonance imaging (MRI), molecular imaging with FDG PET/CT is an important tool in PDAC, for all disease stages. Further prospective studies will be necessary to confirm the cost-effectiveness of such imaging techniques by testing its real potential improvement in the clinical management of PDAC.

Prognosis prediction of pancreatic cancer after curative intent surgery using imaging parameters derived from F-18 fluorodeoxyglucose positron emission tomography/computed tomography

Imaging parameters including metabolic or textural parameters during F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) are being used for evaluation of malignancy. However, their utility for prognosis prediction has not been thoroughly investigated. Here, we evaluated the prognosis prediction ability of imaging parameters from preoperative FDGPET/CT in operable pancreatic cancer patients.Sixty pancreatic cancer patients (male:female = 36:24, age = 67.2 ± 10.5 years) who had undergone FDGPET/CT before the curative intent surgery were enrolled. Clinico-pathologic parameters, metabolic parameters from FDGPET/CT; maximal standard uptake value (SUVmax), glucose-incorporated SUVmax (GI-SUVmax), metabolic tumor volume, total-lesion glycolysis, and 53 textural parameters derived from imaging analysis software (MaZda version 4.6) were compared with overall survival.All the patients underwent curative resection. Mean and standard deviation of overall follow-up duration was 16.12 ± 9.81months. Among them, 39 patients had died at 13.46 ± 8.82 months after operation, whereas 21 patients survived with the follow-up duration of 18.56 ± 9.97 months. In the univariate analysis, Tumor diameter ≥4 cm (P = .003), Preoperative Carbohydrate antigen 19-9 ≥37 U/mL (P = .034), number of metastatic lymph node (P = .048) and GI-SUVmax (P = .004) were significant parameters for decreased overall survival. Among the textural parameters, kurtosis3D (P = .052), and skewness3D (P = .064) were potentially significant predictors in the univariate analysis. However, in multivariate analysis only GI-SUVmax (P = .026) and combined operation (P = .001) were significant independent predictors of overall survival.The current research result indicates that metabolic parameter (GI-SUVmax) from FDGPET/CT, and combined operation could predict the overall survival of surgically resected pancreatic cancer patients. Other metabolic or textural imaging parameters were not significant predictors for overall survival of localized pancreatic cancer.

Prognostic Implications of 18-FDG Positron Emission Tomography/Computed Tomography in Resectable Pancreatic Cancer

There are currently no known preoperative factors for determining the prognosis in pancreatic cancer. The aim of this study was to examine the role of 18-fluorodeoxyglucose (18-FDG) positron emission tomography/computed tomography (18-FDG-PET/CT) as a prognostic factor for patients with resectable pancreatic cancer. Data were obtained from a retrospective analysis of patients who had a preoperative PET scan and then underwent pancreatic resection from January 2007 to December 2015. The maximum standardized uptake value (SUVmax) of 18-FDG-PET/CT was calculated. Patients were divided into high (>3.65) and low (≤3.65) SUVmax groups, and compared in terms of their TNM classification (Union for International Cancer Contro classification), pathological grade, surgical treatment, state of resection margins, lymph node involvement, age, sex, diabetes and serum Carbohydrate Antigen 19-9 (CA 19-9) levels. The study involved 144 patients, 82 with high SUVmax pancreatic cancer and 62 with low SUVmax disease. The two groups’ disease-free and overall survival rates were significantly influenced by tumor stage, lymph node involvement, pathological grade, resection margins and SUVmax. Patients with an SUVmax ≤ 3.65 had a significantly better survival than those with SUVmax > 3.65 (p < 0.001). The same variables were independent predictors of survival on multivariate analysis. The SUVmax calculated with 18-FDG-PET/CT is an important prognostic factor for patients with pancreatic cancer, and may be useful in decisions concerning patients’ therapeutic management.

Mechanistic Multiscale Pharmacokinetic Model for the Anticancer Drug 2',2'-difluorodeoxycytidine (Gemcitabine) in Pancreatic Cancer

The aim of this work is to build a mechanistic multiscale pharmacokinetic model for the anticancer drug 2’,2’‐difluorodeoxycytidine (gemcitabine, dFdC), able to describe the concentrations of dFdC metabolites in the pancreatic tumor tissue in dependence of physiological and genetic patient characteristics, and, more in general, to explore the capabilities and limitations of this kind of modeling strategy. A mechanistic model characterizing dFdC metabolic pathway (metabolic network) was developed using in vitro literature data from two pancreatic cancer cell lines. The network was able to describe the time course of extracellular and intracellular dFdC metabolites concentrations. Moreover, a physiologically‐based pharmacokinetic model was developed to describe clinical dFdC profiles by using enzymatic and physiological information available in the literature. This model was then coupled with the metabolic network to describe the dFdC active metabolite profile in the pancreatic tumor tissue. Finally, global sensitivity analysis was performed to identify the parameters that mainly drive the interindividual variability for the area under the curve (AUC) of dFdC in plasma and of its active metabolite (dFdCTP) in tumor tissue. From this analysis, cytidine deaminase (CDA) concentration was identified as the main driver of plasma dFdC AUC interindividual variability, whereas CDA and deoxycytidine kinase concentration mainly explained the tumor dFdCTP AUC variability. However, the lack of in vitro and in vivo information needed to characterize key model parameters hampers the development of this kind of mechanistic approach. Further studies to better characterize pancreatic cell lines and patient enzymes polymorphisms are encouraged to refine and validate the current model.

Usefulness of FDG PET/CT derived parameters in prediction of histopathological finding during the surgery in patients with pancreatic adenocarcinoma

Purpose

Pancreatic cancer is the 4th most common cause of cancer death in Japan and exhibits a 5-year overall survival rate of approximately 7%. The accurate diagnosis of pancreatic cancer is important for determining the optimal management strategy. Fludeoxyglucose-positron emission tomography (FDG PET) integrated with computed tomography (¹⁸F-FDG PET/CT) has emerged as a powerful imaging tool for detecting and evaluating various cancers, and it is used for staging, detecting local recurrence and distant metastasis, measuring therapeutic effects, and predicting prognosis in pancreatic cancer patients.

Lately, FDG PET/CT-derived parameters, such as standardized uptake values (SUV), the metabolic tumor volume (MTV), and total lesion glycolysis (TLG), have been suggested as prognostic factors for various types of cancer, including pancreatic cancer. However, there is no consensus regarding the best parameters for evaluating patient prognosis, operability, etc. The purpose of this study was to examine the differences between operable and non-operable pancreatic cancer using FDG PET/CT-derived parameters, and to investigate whether volumetric parameters (TLG and the MTV) are superior to SUV-based parameters for predicting infiltration status/determining operability.

Materials and methods

We conducted a retrospective study of the cases of 48 patients with clinically proven pancreatic adenocarcinoma, who underwent FDG PET/CT imaging before treatment. In the operable group, the surgical specimens were subjected to histopathological examinations, and the cases were separated into those exhibiting less and greater infiltration. SUVmax, SUVpeak, the tumor background ratio (TBR), TLG, and the MTV were compared between these groups as well as between the operable and non-operable groups.

Results

Venous infiltration showed significant associations with several metabolic parameters (SUVmax, SUVpeak, and the TBR). However, it did not display any significant associations with volumetric parameters, such as TLG or the MTV. None of the FDG PET/CT-derived parameters exhibited significant associations with lymphatic or neural infiltration. Significant differences in volumetric parameters, such as the MTV and TLG, were detected between the operable and non-operable subgroups.

Conclusions

Metabolic ¹⁸F-FDG PET/CT-derived parameters, such as SUVmax, SUVpeak, and the TBR, are useful for predicting venous infiltration status in patients with operable pancreatic adenocarcinoma.

PET imaging in adaptive radiotherapy of gastrointestinal tumors

INTRODUCTION

Radiotherapy is a cornerstone in the multimodality treatment of several gastrointestinal (GI) tumors. Positron-emission tomography (PET) has an established role in the diagnosis, response assessment and (re-)staging of these tumors. Nevertheless, the value of PET in adaptive radiotherapy remains unclear. This review focuses on the role of PET in adaptive radiotherapy, i.e. during the treatment course and in the delineation process.

EVIDENCE ACQUISITION

The MEDLINE database was searched for the terms ("Radiotherapy"[Mesh] AND "Positron-Emission Tomography"[Mesh] AND one of the site-specific keywords, yielding a total of 1710 articles. After abstract selection, 27 papers were identified for esophageal neoplasms, 1 for gastric neoplasms, 9 for pancreatic neoplasms, 6 for liver neoplasms, 1 for biliary tract neoplasms, none for colonic neoplasms, 15 for rectal neoplasms and 12 for anus neoplasms.

EVIDENCE SYNTHESIS

The use of PET for truly adaptive radiotherapy during treatment for GI tumors has barely been investigated, in contrast to the potential of the PET-defined metabolic tumor volume for optimization of the target volume. The optimized target definition seems useful for treatment individualization such as focal boosting strategies in esophageal, pancreatic and anorectal cancer. Nevertheless, for all GI tumors, further investigation is needed.

CONCLUSIONS

In general, too little data are available to conclude on the role of PET imaging during radiotherapy for ART strategies in GI cancer. On the other hand, based on the available evidence, the use of biological imaging for target volume adaptation seems promising and could pave the road towards individualized treatment strategies.

Heterogeneity index evaluated by slope of linear regression on 18F-FDG PET/CT as a prognostic marker for predicting tumor recurrence in pancreatic ductal adenocarcinoma

PURPOSE

¹⁸F-Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been investigated as a method to predict pancreatic cancer recurrence after pancreatic surgery. We evaluated the recently introduced heterogeneity indices of ¹⁸F-FDG PET/CT used for predicting pancreatic cancer recurrence after surgery and compared them with current clinicopathologic and ¹⁸F-FDG PET/CT parameters.

METHODS

A total of 93 pancreatic ductal adenocarcinoma patients (M:F = 60:33, mean age = 64.2 ± 9.1 years) who underwent preoperative ¹⁸F-FDG PET/CT following pancreatic surgery were retrospectively enrolled. The standardized uptake values (SUVs) and tumor-to-background ratios (TBR) were measured on each ¹⁸F-FDG PET/CT, as metabolic parameters. Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were examined as volumetric parameters. The coefficient of variance (heterogeneity index-1; SUVmean divided by the standard deviation) and linear regression slopes (heterogeneity index-2) of the MTV, according to SUV thresholds of 2.0, 2.5 and 3.0, were evaluated as heterogeneity indices. Predictive values of clinicopathologic and ¹⁸F-FDG PET/CT parameters and heterogeneity indices were compared in terms of pancreatic cancer recurrence.

RESULTS

Seventy patients (75.3%) showed recurrence after pancreatic cancer surgery (mean recurrence = 9.4 ± 8.4 months). Comparing the recurrence and no recurrence patients, all of the ¹⁸F-FDG PET/CT parameters and heterogeneity indices demonstrated significant differences. In univariate Cox-regression analyses, MTV (P = 0.013), TLG (P = 0.007), and heterogeneity index-2 (P = 0.027) were significant. Among the clinicopathologic parameters, CA19-9 (P = 0.025) and venous invasion (P = 0.002) were selected as significant parameters. In multivariate Cox-regression analyses, MTV (P = 0.005), TLG (P = 0.004), and heterogeneity index-2 (P = 0.016) with venous invasion (P < 0.001, 0.001, and 0.001, respectively) demonstrated significant results.

CONCLUSIONS

The heterogeneity index obtained using the linear regression slope, could be an effective predictor of pancreatic cancer recurrence after pancreatic cancer surgery, in addition to ¹⁸F-FDG PET/CT volumetric parameters and clinicopathologic parameters.

Prognostic Value of FDG PET/CT-Derived Parameters in Pancreatic Adenocarcinoma at Initial PET/CT Staging

OBJECTIVE

The purpose of this study is to evaluate the performance of PET-derived parameters as prognostic markers for overall survival (OS) and progression-free survival (PFS) outcome in patients with pancreatic adenocarcinoma.

MATERIALS AND METHODS

We conducted a retrospective study of 106 patients (62 men and 44 women) with histologically proven pancreatic adenocarcinoma who underwent initial staging FDG PET/CT before treatment. Peak standardized uptake value (SUV), maximum SUV (SUVmax), metabolic tumor volume, and tumor glycolytic activity of the primary pancreatic tumor were measured. Two segmentation methods were performed to obtain the metabolic tumor volume and tumor glycolytic activity for all tumors: a gradient-based segmentation model (metabolic tumor volume and tumor glycolytic activity by gradient edge detection) and a fixed-threshold model with a threshold of 50% of the lesion's SUVmax and peak SUV. Univariate and multivariate Cox regression models were developed including clinical and imaging parameters for OS and PFS.

RESULTS

Multivariate Cox regression analysis showed a statistically significant association between PFS and age, SUVmax, peak SUV, and tumor glycolytic activity by gradient edge detection. There was a statistically significant difference in PFS for patients with values above and below the median cutoff points for SUVmax (hazard ratio [HR], 1.12; p < 0.01), peak SUV (HR, 1.25; p < 0.02), and tumor glycolytic activity measured by gradient edge detection (HR, 1.00; p < 0.02) of the primary tumor. However, multivariate Cox regression analysis showed a statistically significant association only between tumor glycolytic activity by gradient edge detection and OS (p = 0.04), and there was a statistically significant difference in OS between patients with values above and below the median cutoff point for the tumor glycolytic activity by gradient edge detection of the primary tumor (HR, 1.42; p = 0.05).

CONCLUSION

Age, SUVmax, peak SUV, and total lesion glycolysis (i.e., tumor glycolytic activity) of the primary tumor are associated with PFS, and tumor glycolytic activity is associated with OS in patients with pancreatic adenocarcinoma.

Role of fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography in gastrointestinal cancers

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a routine imaging modality for many malignancies and its use is currently increasing. In the present review article, we will summarize the evidence for FDG-PET/CT use in digestive cancers (excluding neuroendocrine tumours), and review the existing recommendations. While PET/CT is nowadays considered to be an important tool in the initial workup of oesophageal and anal cancers, new data are emerging regarding its use in assessing therapeutic efficacy, radiotherapy treatment planning, and detection of recurrence in case of isolated tumour marker elevation. Moreover, PET/CT may help decision making by detecting distant metastatic sites especially in potentially resectable metastatic colorectal cancer and, to a lesser extent, in localized gastric and pancreatic cancers. Finally, incidental focal colonic FDG uptakes require exploration by colonoscopy, as they are often associated with premalignant or malignant lesions.

Usefulness of dual-phase 18F-FDG PET/CT for diagnosing small pancreatic tumors

OBJECTIVES

The usefulness of dual-phase F-fluorodeoxyglucose (F-FDG) positron emission tomography/computed tomography (PET/CT) for pancreatic tumors was investigated including numerous small tumors.

METHODS

Consecutive 116 patients with solid pancreatic tumors were subjected. Maximum standard uptake values (SUVmax) at 1 and 2 hours after FDG injection were defined as early and delayed SUVmax, respectively. Receiver operating characteristic curve was used to determine the optimal cutoff value of early SUVmax. Diagnostic accuracy of dual-phase FDG PET/CT was compared with that of single phase.

RESULTS

The mean ± SD tumor size was 25 ±12 mm in diameter. The level of early SUVmax and proportion of elevated SUVmax in delayed phase were significantly higher in malignancy than those in benignancy for less than 25 mm tumors (4.1 ± 2.6 vs 1.9 ± 0.5, P < 0.001; 89% vs 17%, P < 0.0001) although they did not reach statistical significance for greater than or equal to 25 mm tumors. When diagnostic criteria of dual-phase FDG PET/CT for less than 25 mm tumors were determined as (1) early SUVmax greater than or equal to 2.1 and/or (2) delayed SUVmax greater than early SUVmax, sensitivity, specificity, and over all accuracy of dual-phase FDG PET/CT were better than that of single phase for less than 25 mm tumor (93%, 83%, and 91% vs 79%, 83%, and 80%, respectively).

CONCLUSIONS

Dual-phase FDG PET/CT might be useful for diagnosing small pancreatic tumors.

Prognostic significance of volume-based FDG PET/CT parameters in patients with locally advanced pancreatic cancer treated with chemoradiation therapy

PURPOSE

We investigated the prognostic role of volume-based parameters measured on 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) scans in patients with locally advanced pancreatic cancer (LAPC) treated with chemoradiation therapy (CRT).

MATERIALS AND METHODS

We enrolled 60 patients with LAPC who underwent FDG PET/CT before CRT. Maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of primary pancreatic cancers were measured on FDG PET/CT scans. Treatment response was evaluated according to the Response Evaluation Criteria in Solid Tumors. Survival analysis was performed using the Kaplan-Meier method, and Cox proportional hazard models were used to determine independent prognostic factors.

RESULTS

The progression-free survival (PFS), locoregional progression-free survival (LRFPS), and overall survival (OS) for this population were 6.2, 10.9, and 13.2 months, respectively. The overall treatment response rate was 16.7% at 4 weeks after CRT, and the disease control rate (DCR) was 80.0%. DCR was significantly higher in patients with low SUVmax, MTV, or TLG, and showed strong correlation with longer survival times. On univariate analysis, MTV and TLG were significant prognostic factors for PFS, LRPFS, and OS, together with pre-CRT and post-CRT CA19-9 levels. Multivariate analyses demonstrated that MTV together with the pre-CRT CA19-9 level were independent prognostic factors for PFS, LRPFS, and OS, as was TLG for LRPFS and OS.

CONCLUSION

MTV and the pre-CRT CA19-9 level provided independent prognostic information in patients with LAPC treated with CRT. Volume-based PET/CT parameters may be useful in identifying which subgroup of patients would benefit from radiation therapy as a part of CRT.

Maximum standardized uptake value on 18F-fluoro-2-deoxy-glucose positron emission tomography/computed tomography and glucose transporter-1 expression correlates with survival in invasive ductal carcinoma of the pancreas

OBJECTIVES

The purpose of this study was to assess the correlations among the maximum standardized uptake value (SUVmax) on 18F-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (FDG-PET/CT); the expressions of glucose transporter 1 (GLUT-1), glucose transporter 3, and epidermal growth factor receptor (EGFR); as well as prognosis in patients with invasive ductal carcinoma of the pancreas.

METHODS

A total of 41 patients with surgically resected and histologically proven invasive ductal carcinoma of the pancreas who underwent preoperative FDG-PET/CT were assessed. The SUVmax at the primary tumor site was measured by FDG-PET/CT, and immunohistochemical staining of tumor sections was performed for GLUT-1, glucose transporter 3, and EGFR.

RESULTS

Higher FDG uptake (SUVmax, >3.40) and GLUT-1 expression were significantly associated with shorter overall survival (P < 0.05). The SUVmax was not found to be significantly correlated with clinicopathological characteristics such as TNM classification, lymph node metastasis, and tumor differentiation. The EGFR expression was significantly correlated with the SUVmax (P = 0.024).

CONCLUSIONS

Higher FDG uptake and GLUT-1 expression in invasive ductal carcinoma of the pancreas seems to be an important prognostic factor. In addition, the EGFR expression was significantly correlated with the SUVmax.

The application of functional imaging techniques to personalise chemoradiotherapy in upper gastrointestinal malignancies

Functional imaging gives information about physiological heterogeneity in tumours. The utility of functional imaging tests in providing predictive and prognostic information after chemoradiotherapy for both oesophageal cancer and pancreatic cancer will be reviewed. The benefit of incorporating functional imaging into radiotherapy planning is also evaluated. In cancers of the upper gastrointestinal tract, the vast majority of functional imaging studies have used (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). Few studies in locally advanced pancreatic cancer have investigated the utility of functional imaging in risk-stratifying patients or aiding target volume definition. Certain themes from the oesophageal data emerge, including the need for a multiparametric assessment of functional images and the added value of response assessment rather than relying on single time point measures. The sensitivity and specificity of FDG-PET to predict treatment response and survival are not currently high enough to inform treatment decisions. This suggests that a multimodal, multiparametric approach may be required. FDG-PET improves target volume definition in oesophageal cancer by improving the accuracy of tumour length definition and by improving the nodal staging of patients. The ideal functional imaging test would accurately identify patients who are unlikely to achieve a pathological complete response after chemoradiotherapy and would aid the delineation of a biological target volume that could be used for treatment intensification. The current limitations of published studies prevent integrating imaging-derived parameters into decision making on an individual patient basis. These limitations should inform future trial design in oesophageal and pancreatic cancers.

Prognostic Value of Metabolic Tumor Volume and Total Lesion Glycolysis on Preoperative ¹⁸F-FDG PET/CT in Patients with Pancreatic Cancer

In this study, we aimed to assess the prognostic value of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured on (18)F-FDG PET/CT in pancreatic cancer patients who underwent resection with curative intent.

METHODS

Eighty-seven patients with pancreatic ductal adenocarcinoma who underwent (18)F-FDG PET/CT and subsequent surgical resection with curative intent with (30 patients) or without (57 patients) neoadjuvant therapy were retrospectively enrolled. The maximum standardized uptake value (SUVmax), MTV, and TLG were measured on (18)F-FDG PET/CT in all patients. The prognostic significances of PET/CT parameters and tumor factors for recurrence-free survival (RFS) and overall survival (OS) were evaluated by univariate and multivariate analyses.

RESULTS

Of the 87 patients, 57 (64%) experienced recurrence during the follow-up period. The tumor size, pathologic T (pT) stage, SUVmax, MTV, and TLG were significant prognostic factors for both RFS and OS (P < 0.05) on univariate analyses, and the presence of lymph node metastasis showed significance only for predicting RFS (P < 0.05). On multivariate analyses, the tumor size, MTV, and TLG were independent prognostic factors for RFS, and pT stage, MTV, and TLG were independent prognostic factors for OS. For the 57 patients who did not undergo neoadjuvant treatment, MTV and TLG remained significant predictive factors for tumor recurrence, along with tumor size and SUVmax.

CONCLUSION

MTV and TLG are independent prognostic factors for predicting RFS and OS in patients with pancreatic cancer. Thus, (18)F-FDG PET/CT can provide useful prognostic information for patients undergoing resection of pancreatic cancer with curative intent irrespective of neoadjuvant treatment.

Usefulness of F-18-fluorodeoxyglucose positron emission tomography to confirm suspected pancreatic cancer: a meta-analysis

INTRODUCTION

Pancreatic cancer is among the five most lethal malignancies in the world. Unfortunately, many malignant tumors go undetected by the current primary diagnostic tools. (18)FDG-PET and (18)FDG-PET/CT might be useful to confirm suspected pancreatic cancer.

METHODS

A meta-analysis was performed using all major search engines. Methodological quality of included studies was assessed as well as quality of the PET-protocol. The following pooled estimates served as primary outcome measures: sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy.

RESULTS

Thirty-five studies were included. Pooled estimates for (18)FDG-PET were: sensitivity 90%, specificity 76%, PPV 90%, NPV 76% and accuracy 86%. Pooled estimates for (18)FDG-PET/CT were: sensitivity 90%, specificity 76%, PPV 89%, NPV 78% and accuracy 86%. The pooled sensitivity and specificity for (18)FDG-PET to differentiate between pancreatic cancer and chronic pancreatitis were 90% and 84%, respectively.

CONCLUSION

Both (18)FDG-PET and (18)FDG-PET/CT offer no benefit over the current primary diagnostic tools in diagnosing pancreatic cancer. However, the (18)FDG-PET/CT systems are still improving. We should investigate the sensitivity and specificity of these new systems while reevaluating the tradeoff between false positive and false negative results. Yet, (18)FDG-PET/CT may have a role in the staging of pancreatic cancer, in survival prediction, and may add to other diagnostic information, like histology.

Visualization, imaging and new preclinical diagnostics in radiation oncology

Innovative strategies in cancer radiotherapy are stimulated by the growing knowledge on cellular and molecular tumor biology, tumor pathophysiology, and tumor microenvironment. In terms of tumor diagnostics and therapy monitoring, the reliable delineation of tumor boundaries and the assessment of tumor heterogeneity are increasingly complemented by the non-invasive characterization of functional and molecular processes, moving preclinical and clinical imaging from solely assessing tumor morphology towards the visualization of physiological and pathophysiological processes. Functional and molecular imaging techniques allow for the non-invasive characterization of tissues in vivo, using different modalities, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) and optical imaging (OI). With novel therapeutic concepts combining optimized radiotherapy with molecularly targeted agents focusing on tumor cell proliferation, angiogenesis, and cell death, the non-invasive assessment of tumor microcirculation and tissue water diffusion, together with strategies for imaging the mechanisms of cellular injury and repair is of particular interest. Characterizing the tumor microenvironment prior to and in response to irradiation will help to optimize the outcome of radiotherapy. These novel concepts of personalized multi-modal cancer therapy require careful pre-treatment stratification as well as a timely and efficient therapy monitoring to maximize patient benefit on an individual basis. Functional and molecular imaging techniques are key in this regard to open novel opportunities for exploring and understanding the underlying mechanisms with the perspective to optimize therapeutic concepts and translate them into a personalized form of radiotherapy in the near future.

Automated biological target volume delineation for radiotherapy treatment planning using FDG-PET/CT

BACKGROUND

This study compared manually delineated gross tumour volume (GTV) and automatically generated biological tumour volume (BTV) based on fluoro-deoxy-glucose (FDG) positron emission tomography (PET)/CT to assess the robustness of predefined PET algorithms for radiotherapy (RT) planning in routine clinical practice.

METHODS

RT-planning data from 20 consecutive patients (lung- (40%), oesophageal- (25%), gynaecological- (25%) and colorectal (10%) cancer) who had undergone FDG-PET/CT planning between 08/2010 and 09/2011 were retrospectively analysed, five of them underwent neoadjuvant chemotherapy before radiotherapy. In addition to manual GTV contouring, automated segmentation algorithms were applied-among these 38%, 42%, 47% and 50% SUVmax as well as the PERCIST total lesion glycolysis (TLG) algorithm. Different ratios were calculated to assess the overlap of GTV and BTV including the conformity index and the ratio GTV included within the BTV.

RESULTS

Median age of the patients was 66 years and median tumour SUVmax 9.2. Median size of the GTVs defined by the radiation oncologist was 43.7 ml. Median conformity indices were between 30.0-37.8%. The highest amount of BTV within GTV was seen with the 38% SUVmax algorithm (49.0%), the lowest with 50% SUVmax (36.0%). Best agreement was obtained for oesophageal cancer patients with a conformity index of 56.4% and BTV within GTV ratio of 71.1%.

CONCLUSIONS

At present there is only low concordance between manually derived GTVs and automatically segmented FDG-PET/CT based BTVs indicating the need for further research in order to achieve higher volumetric conformity and therefore to get access to the full potential of FDG-PET/CT for optimization of radiotherapy planning.

Tumor size as measured at initial X-ray examination, not length of bile duct stricture, predicts survival in patients with unresectable pancreatic cancer

Background

The survival of unresectable pancreatic cancer patients is extremely poor. The aim of this study was to examine if tumor size could predict survival length in order to optimize patient care.

Methods

A retrospective observational study was performed on 185 consecutive patients with unresectable pancreatic cancer (ICD10: C250-2 and C258) who were diagnosed from 2003 to May 2010. The patients' initial radiographs at presentation of symptoms were reviewed by the same radiologist, and tumor extent was determined.

Results

The largest tumor diameter of the primary tumor was measured in 132 patients, 22 by an ultrasound and the other patients by a CT scan. In 53 patients, the tumor size could not be delimited and measured. Seventy-five patients (41%) had liver metastases at presentation of symptoms. Median survival for the entire patient group was only 119 days. The median diameter of the patient’s largest tumor was 4.35 cm, while the sample groups ranged from 1.2 to 14 cm. Patients were divided into two groups: those with a largest tumor diameter of ≤ 4.3 cm (66 patients) and those with a largest tumor diameter of > 4.3 cm (66 patients). Median survival for these groups was 149 and 94 days (p = 0.019), respectively. Cox regression showed a hazard ratio for tumor size of 1.48 (95% CI 1.02, 2.07) (p = 0.038), adjusted for the gemcitabine treatment which had been given to 49 patients and the presence of liver metastasis. In 88 patients, stricture length could be measured at ERCP. When comparing stricture lengths of ≤ 2 cm and > 2 cm, no difference in survival time was noted within a Kaplan-Meier analysis.

Conclusion

The size of the maximum tumor diameter of the primary tumor during the initial X-ray examination of patients with pancreatic cancer may predict survival time for those patients who had no surgical resection. Stricture length at ERCP gave no information on survival.