Neuroendocrine Pulmonary Tumors of Low, Intermediate and High Grade: Anatomopathological Diagnosis—Prognostic and Predictive Factors

A Systematic Review on Combined [18F]FDG and 68Ga-SSA PET/CT in Pulmonary Carcinoid

Pulmonary carcinoids (PCs) are part of a spectrum of well-differentiated neuroendocrine neoplasms (NENs) and are classified as typical carcinoid (TC) and atypical carcinoid (AC). TC differ from AC not only for its histopathological features but also for its "functional imaging pattern" and prognosis. ACs are more undifferentiated and characterized by higher aggressiveness. Positron emission tomography/computed tomography (PET/CT) with somatostatin analogs (SSA) labeled with Gallium-68 (⁶⁸Ga-DOTA-TOC, ⁶⁸Ga-DOTA-NOC, ⁶⁸Ga-DOTA-TATE) has widely replaced conventional imaging with gamma camera using ¹¹¹In- or ^99mTc-labelled compounds and represents now the gold standard for diagnosis and management of NENs. In this setting, as already described for gastro-entero-pancreatic NENs, ¹⁸F-Fluorodeoxiglucose ([¹⁸F]FDG) in addition to ⁶⁸Ga-SSA can play an important role in clinical practice, particularly for ACs that show a more aggressive behavior compared to TCs. The aim of this systematic review is to analyze all original studies collected from the PubMed and Scopus databases regarding PCs in which both ⁶⁸Ga-SSA PET/CT and [¹⁸F]FDG PET/CT were performed in order to evaluate the clinical impact of each imaging modality. The following keywords were used for the research: "¹⁸F, ⁶⁸Ga and (bronchial carcinoid or carcinoid lung)". A total of 57 papers were found, of which 17 were duplicates, 8 were reviews, 10 were case reports, and 1 was an editorial. Of the remaining 21 papers, 12 were ineligible because they did not focus on PC or did not compare ⁶⁸Ga-SSA and [¹⁸F]FDG. We finally retrieved and analyzed nine papers (245 patients with TCs and 110 patients with ACs), and the results highlight the importance of the combined use of ⁶⁸Ga-SSA and [¹⁸F]FDG PET/CT for the correct management of these neoplasms.

SOX11 is a sensitive and specific marker for pulmonary high-grade neuroendocrine tumors

BACKGROUND

Synaptophysin (SYN), chromogranin A (CGA), CD56 and insulinoma-associated protein 1 (INSM1) are proposed neuroendocrine (NE) markers used for diagnosis of pulmonary NE tumors. These NE markers have been identified in subsets of non-NE tumors requiring differential diagnosis, thus we sought to explore new NE markers.

METHODS

We evaluated the immunohistochemical expression of SOX11, a transcription factor involved in neurogenesis, in pulmonary NE tumors and large cell carcinomas (LCCs).

RESULTS

We found that SOX11 showed a sensitivity similar to INSM1 and CGA, and less than SYN and CD56 in small cell lung carcinomas (SCLCs) and large cell neuroendocrine carcinomas (LCNECs). While SOX11 is more specific than the other four markers for diagnosis of high-grade neuroendocrine carcinomas (HG-NECs) because 1) None of LCCs (0/63), the most challenging non-NE tumor type for differential diagnosis due to overlapped morphology with LCNECs displayed SOX11 positivity. While expression of at least one of SYN, CGA, CD56 or INSM1 was identified in approximately 60% (18/30) of LCCs. 2) SOX11 was only expressed in 1 of 37 carcinoid tumors in contrast to diffuse expression of SYN, CGA, CD56 and INSM1. In HG-NECs, we noticed that SOX11 was a good complementary marker for SCLC diagnosis as it was positive in 7 of 18 SYN^-/CGA^-/CD56^- SCLCs and 3 of 8 SYN^-/CGA^-/CD56^-/INSM1^- SCLCs, and SOX11 positivity in 4 of 6 SYN^-/CGA^-/CD56^- cases previously diagnosed as LCCs with NE morphology provides additional evidence of NE differentiation for reclassification into LCNECs, which was further confirmed by electromicroscopical identification of neurosecretory granules. We also found SOX11 expression cannot predict the prognosis in patients with HG-NECs.

CONCLUSIONS

Therefore, SOX11 is a useful complementary transcriptional NE marker for diagnosis and differential diagnosis of SCLC and LCNEC.

99mTc-EDDA/HYNIC-TOC is a New Opportunity in Neuroendocrine Tumors of the Lung (and in other Malignant and Benign Pulmonary Diseases)

Neuroendocrine tumors (NETs) consist of a relatively rare spectrum of malignancies that can arise from neuroendocrine cells; lung NETs (L-NETs) represent about 25% of primary lung neoplasm and 10% of all carcinoid tumors. Diagnostic algorithm usually takes into consideration chest Xray, contrast-enhanced CT and MRI. Nuclear medicine plays a crucial role in the detection and correct assessment of neoplastic functional status as it provides in vivo metabolic data related to the overexpression of Somatostatin Receptors (SSTRs) and also predicting response to peptide receptor radionuclide therapy (PRRT). 111In-Pentreotide (Octreoscan®) is commercially available for imaging of neuroendocrine tumors, their metastases and the management of patients with NETs. More recently, 99mTc-EDDA/HYNIC-TOC(Tektrotyd®) was introduced into the market and its use has been approved for imaging of patients with L-NETs and other SSTR-positive tumors. 99mTc-EDDA/HYNIC-TOC could also represent a good alternative to 68Ga-DOTA-peptides (DOTA-TOC, DOTA-NOC, DOTATATE) in hospitals or centers where PET/CT or 68Ge/68Ga generators are not available. When compared to 111In-Pentetreotide, Tektrotyd® showed slightly higher sensitivity, in the presence of higher imaging quality and lower radiation exposure for patients. Interesting perspectives depending on the kinetic analysis allowed by Tektrotyd® may be obtained in differential diagnosis of non-small cells lung cancer (NSCLC) versus small cells lung cancer (SCLC) and NETs. An interesting perspective could be also associated with a surgery radio-guided by Tektrotyd® in operable lung tumors, including either NETs and NSCLC.

Characteristics of 252 patients with bronchopulmonary neuroendocrine tumours treated at the Copenhagen NET Centre of Excellence

BACKGROUND

Bronchopulmonary neuroendocrine tumours are divided into typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC), and small cell lung cancer (SCLC).

AIM

To thoroughly describe a cohort of 252 patients with TC, AC and LCNEC (SCLC excluded).

MATERIAL AND METHODS

Collection of data from 252 patients referred to and treated at Rigshospitalet 2008-2016. Data was collected from electronic patient files and our prospective NET database. Statistics were performed in SPSS.

RESULTS

162 (64%) had TC, 29 (12%) had AC and 61 (24%) had LCNEC. Median age at diagnosis was 69 years (range: 19-89) with no difference between genders. Thoraco-abdominal CT was performed in all patients at diagnosis. FDG-PET/CT was performed in 207 (82%) at diagnosis and was positive in 95% of the entire cohort, with no difference between tumour types. Synaptophysin was positive in 98%, chromogranin A in 92% and CD56 in 97%. Mean Ki67 index was 5% in TC, 16% in AC and 69% in LCNEC (p < 0.001). Metastatic disease was found in 4% of TC, 27% of AC and 58% of LCNEC at time of initial diagnosis (p < 0.001). In total 179 patients (71%) underwent surgical resection; TC: 87%, AC: 72% and LCNEC: 28% (p < 0.001). Of the resected patients, 11 (6%) had recurrence. Five-year survival rate was 88% for TC, 63% for AC and 20% for LCNEC.

CONCLUSION

In this comprehensive study of a cohort of 252 patients, one of the largest until date, with TC, AC and LCNEC, the gender distribution showed female predominance with 68%. FDG-PET/CT was positive in 95% of the patients independent of tumour type, which confirms that FDG-PET/CT should be a part of the preoperative work-up for TC, AC and LCNEC. Tumour type was the single most potent independent prognostic factor.

Somatostatin Analogue Treatment Primarily Induce miRNA Expression Changes and Up-Regulates Growth Inhibitory miR-7 and miR-148a in Neuroendocrine Cells

Somatostatin (SST) analogues are used to control the proliferation and symptoms of neuroendocrine tumors (NETs). MicroRNAs (miRNA) are small non-coding RNAs that modulate posttranscriptional gene expression. We wanted to characterize the miRNAs operating under the control of SST to elucidate to what extent they mediate STT actions. NCI-H727 carcinoid cell line was treated with either a chimeric SST/dopamine analogue; a SST or dopamine analogue for proliferation assays and for identifying differentially expressed miRNAs using miRNA microarray. The miRNAs induced by SST analogue treatment are investigated in carcinoid cell lines NCI-H727 and CNDT2 using in situ hybridization, qPCR and proliferation assays. SST analogues inhibited the growth of carcinoid cells more potently compared to the dopamine analogue. Principal Component Analysis (PCA) of the samples based on miRNA expression clearly separated the samples based on treatment. Two miRNAs which were highly induced by SST analogues, miR-7 and miR-148a, were shown to inhibit the proliferation of NCI-H727 and CNDT2 cells. SST analogues also produced a general up-regulation of the let-7 family members. SST analogues control and induce distinct miRNA expression patterns among which miR-7 and miR-148a both have growth inhibitory properties.