Neuroendocrine tumors of the lung: hystological classification, diagnosis, traditional and new therapeutic approaches

The diagnostic and prognostic role of combined [18F]FDG and [68Ga]-DOTA-peptides PET/CT in primary pulmonary carcinoids: a multicentric experience

OBJECTIVES

In the present retrospective multicentric study, we combined [68Ga]-DOTA-peptides and [18F]FDG-PET/CT findings aiming to investigate their capability to differentiate typical (TC) and atypical pulmonary carcinoids (AC) and their prognostic role.

METHODS

From three centers, 61 patients were retrospectively included. Based on a dual tracer combination we classified PET scans as score 1, [18F]FDG- and [68Ga]-DOTA-peptides negative; score 2, [68Ga]-DOTA-peptides positive and [18F]FDG-negative; score 3, [68Ga]-DOTA-peptides negative and [18F]FDG-positive; score 4, both tracers positive. Moreover, for each patient, the ratios of SUVmax on [68Ga]-DOTA-PET to that on [18F]FDG-PET were calculated (SUVr).

RESULTS

Thirty-five patients had a final diagnosis of TC. Twenty-two TC (57%) had positive [68Ga]-DOTA-peptides PET; instead, 21/26 (81%) AC had positive [18F]FDG-PET/CT. On dual-tracer analysis, scores 1, 2, 3 and 4 were 13%, 20%, 43% and 24% for all populations; 17%, 26%, 20% and 37% for TC; 8%, 11%, 73% and 8% for AC. Median SUVr was significantly higher in TC than AC (6.4 vs. 0.4, p = 0.011). The best value of SUVr to predict the final diagnosis was 1.05 (AUC 0.889). Relapse or progression of disease happened in 17 patients (11 affected by AC) and death in 10 cases (7 AC). AC diagnosis, positive [18F]FDG-PET, negative DOTA-PET and dual tracer score were significantly correlated with PFS (p = 0.013, p = 0.033, p = 0.029 and p = 0.019), while only AC diagnosis with OS (p = 0.022).

CONCLUSION

PET/CT findings had also a prognostic role in predicting PFS. Dual-tracer PET behavior may be used to predict the nature of pulmonary carcinoids and select the most appropriate management.

KEY POINTS

• Combination of [18F]FDG and [68Ga]-DOTA-peptides PET/CT results may help to differentiate between atypical and typical lung carcinoids. • The SUVmax ratio between [18F]FDG and [68Ga]-DOTA-peptides PET may help to differentiate between atypical and typical lung carcinoids. • Histotype and PET/CT features have a prognostic impact on PFS.

Heterogeneity of Vascular Endothelial Cells, De Novo Arteriogenesis and Therapeutic Implications in Pancreatic Neuroendocrine Tumors

Arteriogenesis supplies oxygen and nutrients in the tumor microenvironment (TME), which may play an important role in tumor growth and metastasis. Pancreatic neuroendocrine tumors (pNETs) are the second most common pancreatic malignancy and are frequently metastatic on presentation. Nearly a third of pNETs secrete bioactive substances causing debilitating symptoms. Current treatment options for metastatic pNETs are limited. Importantly, these tumors are highly vascularized and heterogeneous neoplasms, in which the heterogeneity of vascular endothelial cells (ECs) and de novo arteriogenesis may be critical for their progression. Current anti-angiogenetic targeted treatments have not shown substantial clinical benefits, and they are poorly tolerated. This review article describes EC heterogeneity and heterogeneous tumor-associated ECs (TAECs) in the TME and emphasizes the concept of de novo arteriogenesis in the TME. The authors also emphasize the challenges of current antiangiogenic therapy in pNETs and discuss the potential of tumor arteriogenesis as a novel therapeutic target. Finally, the authors prospect the clinical potential of targeting the FoxO1-CD36-Notch pathway that is associated with both pNET progression and arteriogenesis and provide insights into the clinical implications of targeting plasticity of cancer stem cells (CSCs) and vascular niche, particularly the arteriolar niche within the TME in pNETs, which will also provide insights into other types of cancer, including breast cancer, lung cancer, and malignant melanoma.

A Case Analysis on CT Guided Percutaneous Lung Puncture Biopsy of Lymphocyte Mesenchymal Pneumonia

OBJECTIVE

To explore the application and diagnostic value of high-resolution CT in the process of lymphocytic interstitial pneumonia clinical diagnosis, and analyze one case of CT-guided percutaneous lung biopsy lymphocytic interstitial pneumonia.

METHODS

The medical record of a patient with lymphocyte interstitial pneumonia (LIP) who came to the clinic on 2014-04-22 were analyzed and summarized retrospectively.

RESULTS

The patient was a 55 years old female farmer. The CT-guided percutaneous lung biopsy was performed at her first visit; on 2014-07-09, the patient returned to our outpatient clinic with the main complaint of "1 week of coughing and blood in sputum and phlegm". Pathology consultation report from the PLA General Hospital on 2014-07-29 showed: (right lower lung) pneumonic pseudo-tumor; Zhejiang First Hospital's pathology consultation report on 2014-08-11 showed: lymphocyte interstitial pneumonia.

CONCLUSION

The diagnosis of lymphocyte interstitial pneumonia (LIP) with high-resolution CT may be used to increase its clinical diagnosis rate, reduce misdiagnosis and improve early detection.

Wnt/Beta-Catenin Signaling and Prostate Cancer Therapy Resistance

Metastatic or locally advanced prostate cancer (PCa) is typically treated with androgen deprivation therapy (ADT). Initially, PCa responds to the treatment and regresses. However, PCa almost always develops resistance to androgen deprivation and progresses to castrate-resistant prostate cancer (CRPCa), a currently incurable form of PCa. Wnt/β-Catenin signaling is frequently activated in late stage PCa and contributes to the development of therapy resistance. Although activating mutations in the Wnt/β-Catenin pathway are not common in primary PCa, this signaling cascade can be activated through other mechanisms in late stage PCa, including cross talk with other signaling pathways, growth factors and cytokines produced by the damaged tumor microenvironment, release of the co-activator β-Catenin from sequestration after inhibition of androgen receptor (AR) signaling, altered expression of Wnt ligands and factors that modulate the Wnt signaling, and therapy-induced cellular senescence. Research from genetically engineered mouse models indicates that activation of Wnt/β-Catenin signaling in the prostate is oncogenic, enables castrate-resistant PCa growth, induces an epithelial-to-mesenchymal transition (EMT), promotes neuroendocrine (NE) differentiation, and confers stem cell-like features to PCa cells. These important roles of Wnt/β-Catenin signaling in PCa progression underscore the need for the development of drugs targeting this pathway to treat therapy-resistant PCa.

Molecular challenges of neuroendocrine tumors

Neuroendocrine tumors (NETs) are a very heterogeneous group that are thought to originate from the cells of the endocrine and nervous systems. These tumors develop in a number of organs, predominantly in the gastrointestinal and pulmonary systems. Clinical detection and diagnosis are reliable at the late stages when metastatic spread has occurred. However, traditional conventional therapies such as radiation and chemotherapy are not effective. In the majority of cases even surgical resection at that stage is unlikely to produce promising reusults. NETs present a serious clinical challenge, as the survival rates remain low, and as these rare tumors are very difficult to study, novel approaches and therapies are required. This review will highlight the important points of accumulated knowledge covering the molecular aspects of the role of neuroendocrine cells, hormonal peptides, the reasons for ectopic hormone production in NET, neuropeptides and epigenetic regulation as well as the other challenging questions that require further understanding.

Expression of hsa-let-7b-5p, hsa-let-7f-5p, and hsa-miR-222-3p and their putative targets HMGA2 and CDKN1B in typical and atypical carcinoid tumors of the lung

Typical and atypical carcinoid tumors belong to the neuroendocrine lung tumors. They have low recurrence and proliferation rate, lymph node, and distant metastases. Nevertheless, these tumors have shown a more aggressive behavior. In the last years, microRNAs were screened as new tumor markers for their potential diagnostic and therapeutic relevance. The expression of hsa-let-7b-5p, hsa-let-7f-5p, hsa-miR-222-3p, and their targets HMGA2 (high-mobility group A2) and CDKN1B (cyclin-dependent kynase inhibitor 1B, p27^kip1) was evaluated in this rare small group of patients. We analyzed the clinical data of all typical and atypical carcinoid tumors of patients who underwent surgical operation at Marburg University Hospital (n = 18) from 2000. Quantitative reverse transcription polymerase chain reaction was performed in formalin-fixed paraffin-embedded tumor tissue versus four tumor-free lung tissue samples. HMGA2 was stable or downregulated; only one patient showed a significant overexpression. CDKN1B showed a significant overexpression or a stable level; it was downregulated in two samples only. Hsa-miR-222-3p resulted almost stable or overexpressed except for two samples (significantly downregulated). Hsa-let-7f-5p was stable or overexpressed in the majority of analyzed samples, whereas hsa-let-7b-5p was significantly downregulated. HMGA2 and CDKN1B are differently expressed between atypical and typical carcinoid tumors, thus representing valid biomarkers for the classification of the two tumor groups. Hsa-let-7f-5p and HMGA2 are inversely correlated. Hsa-miR-222-3p does not correlate with its predicted target CDKN1B.

Functional imaging evaluation in the detection, diagnosis, and histologic differentiation of pulmonary neuroendocrine tumors

Pulmonary neuroendocrine tumors (pNETs) have distinct pathologic characteristics. Typical carcinoids are indolent neoplasms with a good prognosis, whereas atypical carcinoids have a less indolent behavior. Both are optimally treated with complete surgical excision. More aggressive pNETs often present with local invasion, thoracic lymph nodal metastases, and distant spread. Patients may not be candidates for surgical resection and are treated with chemotherapy and/or radiation therapy. This article examines the potential role of functional imaging evaluation using (18)F FDG and somatostatin analogues labeled with (68)Ga DOTA-peptides in well-differentiated pNETs with particular attention to clinical and surgical implications.

PET/CT assessment of neuroendocrine tumors of the lung with special emphasis on bronchial carcinoids

Pulmonary neuroendocrine tumors (pNETs) arise from bronchial mucosal cells known as enterochromaffin cells which are part of the diffuse neuroendocrine system. The pathological spectrum of pNETs ranges from low-/intermediate-grade neoplasms such as bronchial carcinoids (BCs), also known as typical or atypical carcinoids, to high-grade neoplasms as large-cell neuroendocrine carcinoma and small-cell lung cancer. The tumor biology of pNETs still represents a matter of open debate. The distinct features among the different pNETs include not only their pathologic characteristics but also their clinical behavior, epidemiology, treatment, and prognosis. In this sense, a correct pathological identification in the preoperative setting is a key element for planning the best strategy of care in pNETs and especially in BCs. Controversial results have been reported on the diagnostic accuracy of fluorine-18-fluorodeoxyglucose positron emission tomography or positron emission tomography/computed tomography (F-18-FDG PET or PET/CT) in BCs. On the other hand, there is increasing evidence supporting the use of PET with somatostatin analogues (DOTA-TOC, DOTA-NOC, or DOTA-TATE) labeled with gallium-68 (Ga-68) in pNETs. Herein, we review the pertinent literature aiming to better define the current state of art of PET/CT in the detection and histological differentiation of pNETs with special emphasis on BCs.