Predictive prognostic value of local and distant recurrence of F-fluorodeoxyglucose positron emission tomography for pancreatic neuroendocrine tumors with reference to World Health Organization classifications (2004, 2010). Case series study

Pancreatic neuroendocrine tumor: prediction of tumor grades by radiomics models based on ultrasound images

OBJECTIVE

We aimed to investigate whether the radiomics analysis based on B-mode ultrasound (BMUS) images could predict histopathological tumor grades in pancreatic neuroendocrine tumors (pNETs).

METHODS

A total of 64 patients with surgery and histopathologically confirmed pNETs were retrospectively included (34 male and 30 female, mean age 52.4 ± 12.2 years). Patients were divided into training cohort (n = 44) and validation cohort (n = 20). All pNETs were classified into Grade 1 (G1), Grade 2 (G2), and Grade 3 (G3) tumors based on the Ki-67 proliferation index and the mitotic activity according to WHO 2017 criteria. Maximum relevance minimum redundancy, least absolute shrinkage and selection operator were used for feature selection. Receiver operating characteristic curve analysis was used to evaluate the model performance.

RESULTS

Finally, 18 G1 pNETs, 35 G2 pNETs, and 11 G3 pNETs patients were included. The radiomic score derived from BMUS images to predict G2/G3 from G1 displayed a good performance with an area under the receiver operating characteristic curve of 0.844 in the training cohort, and 0.833 in the testing cohort. The radiomic score achieved an accuracy of 81.8% in the training cohort and 80.0% in the testing cohort, a sensitivity of 0.750 and 0.786, a specificity of 0.833 and 0.833 in the training/testing cohorts. Clinical benefit of the score also exhibited superior usefulness of the radiomic score, as shown by the decision curve analysis.

CONCLUSIONS

Radiomic data constructed from BMUS images have the potential for predicting histopathological tumor grades in patients with pNETs.

ADVANCES IN KNOWLEDGE

The radiomic model constructed from BMUS images has the potential for predicting histopathological tumor grades and Ki-67 proliferation indexes in patients with pNETs.

Prognostic Value of 18F-FDG PET in Neuroendocrine Neoplasm: A Systematic Review and Meta-analysis

OBJECTIVES

Accurate assessment of the prognosis is critical for the rational treatment of neuroendocrine neoplasms (NENs). We performed a systematic review and meta-analysis of the prognostic value of 18F-FDG PET for NENs.

PATIENTS AND METHODS

PubMed and Embase databases were searched up to September 2020 for studies that evaluated 18F-FDG PET as prognostic factors in patients with NENs with overall survival (OS) and event-free survival (EFS) as outcomes. Hazards ratios (HRs) comparing high and low FDG uptakes were pooled using the DerSimonian-Laird method. Publication bias was assessed and adjusted for using the trim-and-fill method. Metaregression and subgroup analyses were performed to explore the cause of heterogeneity.

RESULTS

Twenty-three studies (1799 patients) were included. The overall pooled HRs of high FDG uptake on EFS and OS were 2.84 (95% confidence interval [CI], 2.21-3.64) and 3.50 (95% CI, 2.42-4.12), respectively. Publication biases were present regarding both EFS and OS (P = 0.0342 and 0.0009, respectively). After adjustment, effect sizes remained significant for EFS and OS (adjusted HR, 2.26 [95% CI, 1.76-2.89]; 3.16 [95% CI, 2.42-4.12]). In metaregression analyses, the proportion of grade 3 tumors positively correlated with the HR of OS (adjusted P = 0.0422).

CONCLUSIONS

18F-FDG PET is a significant prognostic factor in patients with NENs. 18F-FDG PET might be a useful prognostic biomarker in conjunction with the histologic grade and can help select the optimal treatment.

Multiple endocrine neoplasia type 1 (MEN-1) and neuroendocrine neoplasms (NENs)

Neuroendocrine neoplasms (NENs) are relatively rare neoplasms with 6.4-times increasing age-adjusted annual incidence during the last four decades. NENs arise from neuroendocrine cells, which release hormones in response to neuronal stimuli and they are distributed into organs and tissues. The presentation and biological behaviour of the NENs are highly heterogeneous, depending on the organ. The increased incidence is mainly due to increased awareness and improved detection methods both in the majority of sporadic NENs (non-inherited), but also the inherited groups of neoplasms appearing in at least ten genetic syndromes. The most important one is multiple endocrine neoplasia type 1 (MEN-1), caused by mutations in the tumour suppressor gene MEN1. MEN-1 has been associated with different tumour manifestations of NENs e.g. pancreas, gastrointestinal tract, lungs, thymus and pituitary. Pancreatic NENs tend to be less aggressive when arising in the setting of MEN-1 compared to sporadic pancreatic NENs. There have been very important improvements over the past years in both genotyping, genetic counselling and family screening, introduction and validation of various relevant biomarkers, as well as newer imaging modalities. Alongside this development, both medical, surgical and radionuclide treatments have also advanced and improved morbidity, quality of life and mortality in many of these patients. Despite this progress, there is still space for improving insight into the genetic and epigenetic factors in relation to the biological mechanisms determining NENs as part of MEN-1. This review gives a comprehensive update of current evidence for co-occurrence, diagnosis and treatment of MEN-1 and neuroendocrine neoplasms and highlight the important progress now finding its way to international guidelines in order to improve the global management of these patients.

Usefulness of 18 F-FDG-PET/CT in the diagnosis and prediction of recurrence of pancreatic neuroendocrine neoplasms

BACKGROUND

Although ¹⁸ F-FDG-PET/CT is a widely used diagnostic tool for several malignancies, its efficacy in diagnosing pancreatic neuroendocrine tumors is reported to be controversial because of the short-term follow-up.

METHODS

We retrospectively compared demographics and pathological features between ¹⁸ F-FDG-positive and -negative diseases. Additionally, we evaluated whether the avidity of ¹⁸ F-FDG-PET/CT affected earlier recurrence after curative treatment of non-functioning tumors. The median duration of observation was 65.6 months.

RESULTS

Seventy-two patients were enrolled. ¹⁸ F-FDG-positive diseases were pathologically advanced and significantly associated with metastatic behavior. In a multivariate analysis, metastatic behavior and WHO tumor grade was independently associated with ¹⁸ F-FDG accumulation. Only 25% of functional tumors (4/16) and 8% of insulinomas (1/12) were ¹⁸ F-FDG-positive. In a Kaplan-Meier analysis in patients with non-functioning tumors (n = 56), ¹⁸ F-FDG-positivity was significantly correlated with poorer recurrence-free survival (RFS) but had no correlation with overall survival. In univariate analysis of factors associated with shorter RFS, male gender, prevalence of nodal metastasis, WHO tumor grade ≥G2, or ¹⁸ F-FDG-positive disease were significantly higher in patients with shorter RFS, whereas only ¹⁸ F-FDG-positivity was associated with shorter RFS in multivariate analyses.

CONCLUSIONS

The avidity of ¹⁸ F-FDG-PET/CT was associated with metastatic behavior of pancreatic neuroendocrine tumors and recurrence after treatment of non-functioning tumors.

Imaging of pancreatic neuroendocrine tumors: recent advances, current status, and controversies

Recently, there have been a number of advances in imaging pancreatic neuroendocrine tumors (panNETs), as well as other neuroendocrine tumors (NETs), which have had a profound effect on the management and treatment of these patients, but in some cases are also associated with controversies. Areas covered: These advances are the result of numerous studies attempting to better define the roles of both cross-sectional imaging, endoscopic ultrasound, with or without fine-needle aspiration, and molecular imaging in both sporadic and inherited panNET syndromes; the increased attempt to develop imaging parameters that correlate with tumor classification or have prognostic value; the rapidly increasing use of molecular imaging in these tumors and the attempt to develop imaging parameters that correlate with treatment/outcome results. Each of these areas and the associated controversies are reviewed. Expert commentary: There have been numerous advances in all aspects of the imaging of panNETs, as well as other NETs, in the last few years. The advances are leading to expanded roles of imaging in the management of these patients and the results being seen in panNETs/GI-NETs with these newer techniques are already being used in more common tumors.

Contrast-enhanced MDCT in patients with pancreatic neuroendocrine tumours: correlation with histological findings and diagnostic performance in differentiation between tumour grades

AIM

To identify the multidetector computed tomography (MDCT) features of pancreatic neuroendocrine tumours (pNETs), which correlate with tumour histology and enable preoperative grading.

MATERIALS AND METHODS

Thirty-nine patients with histologically confirmed pNET who underwent preoperative contrast-enhanced MDCT were included in this study. Nineteen tumours were classified as Grade 1 (G1) and 20 as Grade 2 (G2). Histopathology slides were reviewed to assess the intratumoural microvascular density (MVD) and the amount of tumour stroma. Computed tomography (CT) image analysis included tumour size, margin delineation, calcifications, homogeneity, contrast enhancement (CE) pattern, tumour absolute and relative enhancement, presence of cystic changes, pancreatic duct dilatation, regional and distant metastases. The diagnostic ability to predict tumour grade was measured for each MDCT finding and their combinations.

RESULTS

The mean arterial enhancement ratio had a mean±standard deviation of 1.53±0.45 in G1 and 1.01±0.33 in G2 pNETs (p=0.0003) and correlated with intratumoural microvascular density (MVD; r=0.55, p=0.0002). Tissue stroma percentage did not correlate with imaging findings. Late CE of the tumour (the peak attenuation observed in the venous phase) was significantly associated with G2. Tumour size >20 mm, arterial enhancement ratio <1.1, and late CE showed 74.4%, 79.5%, and 74.4% accuracy, respectively, in diagnosing G2 tumours, while the accuracy of at least two of these criteria used in combination was 82%. Based on these results, a diagnostic algorithm was proposed, which showed high interobserver agreement (k=0.82) in the prediction of tumour grade.

CONCLUSION

Contrast-enhanced MDCT features correlate with histological findings and enable the differentiation between G1 and G2 pNETs during preoperative examination.