The surgical spectrum of pulmonary neuroendocrine neoplasms

Carcinoid tumors outside the abdomen

Neuroendocrine tumors (NETs) are epithelial malignancies that can arise from multiple tissues. Gastrointestinal (GI) NETs are the most common; in this review of extra-abdominal carcinoid tumors, we focus our discussion on bronchial and thymic carcinoid tumors. Bronchial carcinoid tumors comprise a quarter of all NETs and less than 2% of all lung cancers. Thymic carcinoid tumors are extremely rare, accounting for 5% of thymic tumors. Both bronchial and thymic carcinoid tumors are histologically classified as either typical or atypical based on their mitotic rate (less than 2 or 2-10 mitoses per 10 high-powered fields (HPF), respectively). Both bronchial and thymic carcinoids can present with symptoms of obstruction and potentially carcinoid syndrome. The gold standard of management of bronchial and thymic carcinoid tumors is surgical resection. For patients with advanced disease, first-line systemic therapy is generally somatostatin analog monotherapy with octreotide or lanreotide. In patients with refractory disease, therapy generally involves peptide receptor radioligand therapy, everolimus, or cytotoxic chemotherapy. There are ongoing, prospective trials comparing the mainstays of systemic therapy for these patients, as well as ongoing evaluations of immune checkpoint inhibitors and multi-kinase inhibitors. Prognosis for both bronchial and thymic carcinoid tumors depends on histologic grade, local versus invasive disease, and extent of metastases. Herein we provide a summary of the pathophysiologic and clinical background, the current state of the field in diagnosis and management, and note of key ongoing prospective trials for patients with bronchial and thymic carcinoid tumors.

Clinic and genetic similarity assessments of atypical carcinoid, neuroendocrine neoplasm with atypical carcinoid morphology and elevated mitotic count and large cell neuroendocrine carcinoma

Background

Pulmonary neuroendocrine neoplasms can be divided into typical carcinoid, atypical carcinoid, large cell neuroendocrine carcinoma, and small cell (lung) carcinoma. According to the World Health Organization, these four neoplasms have different characteristics and morphological traits, mitotic counts, and necrotic status. Importantly, “a grey-zone” neoplasm with an atypical carcinoid-like morphology, where the mitotic rate exceeds the criterion of 10 mitoses per 2 mm², have still not been well classified. In clinical practice, the most controversial area is the limit of 11 mitoses to distinguish between atypical carcinoids and large cell neuroendocrine carcinomas.

Methods

Basic and clinical information was obtained from patient medical records. A series of grey-zone patients (n = 8) were selected for exploring their clinicopathological features. In addition, patients with atypical carcinoids (n = 9) and classical large cell neuroendocrine carcinomas (n = 14) were also included to compare their similarity to these neoplasms with respect to tumour morphology and immunohistochemical staining.

Results

We found that these grey-zone tumour sizes varied and affected mainly middle-aged and older men who smoked. Furthermore, similar gene mutations were found in the grey-zone neoplasms and large cell neuroendocrine carcinomas, for the mutated genes of these two are mainly involved in PI3K-Akt signal pathways and Pathways in cancer, including a biallelic alteration of TP53/RB1 and KEAP1.

Conclusions

Our findings indicate that neuroendocrine neoplasm with atypical carcinoid morphology and elevated mitotic counts is more similar to large cell neuroendocrine carcinoma than atypical carcinoid. Furthermore, this study may help improve diagnosing these special cases in clinical practice to avoid misdiagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09391-w.

Clinical Behavior of Combined Versus Pure High-Grade Neuroendocrine Carcinoma

BACKGROUND

The aim of this study was to investigate and compare the clinical behaviors of combined and pure high-grade neuroendocrine carcinoma (large-cell neuroendocrine carcinoma [LCNEC] and small-cell lung carcinoma [SCLC]).

PATIENTS AND METHODS

Data of 132 patients who underwent complete resection for combined or pure high-grade neuroendocrine carcinoma (combined group, 67; pure group, 65) between January 2001 and December 2015 were retrospectively reviewed. The clinicopathological features were analyzed and compared, and the prognoses were assessed by performing the Kaplan-Meier method and Cox regression analysis.

RESULTS

The combined and pure groups had nearly equivalent clinicopathological characteristics, specifically, older males with smoking history, almost the same percentage of pleural/lymphatic/vascular invasion, and nearly the same recurrence rates and relapse patterns. The combined group had prognosis equivalent to that of the pure group (5-year overall survival [OS] rates: 61.8% vs. 52.2%, respectively; P = .82 and 5-year recurrence-free survival [RFS] rates: 42.4% vs. 43.9%, respectively; P = .96), and this trend was identified in sub-analyses only for patients with LCNEC, SCLC, and the same pathological stage. Multivariable Cox regression analysis in patients with high-grade neuroendocrine carcinoma revealed that vascular invasion and pathological stage were independent prognostic factors for OS; more importantly, combined and pure histologies were proven to have nearly equivalent associations with prognosis (hazard ratio, 0.96; 95% confidence interval, 0.22to 1.66; P = .96).

RESULTS

Combined high-grade neuroendocrine carcinoma had clinical behavior equivalent to those of pure high-grade neuroendocrine carcinoma, with similar clinicopathological characteristics.

Outcomes of Patients with Clinical Stage I-IIIA Large-Cell Neuroendocrine Lung Cancer Treated with Resection

Large-cell neuroendocrine carcinoma (LCNEC) is a rare malignancy with poor prognosis. The rationale of the study was to determine the survival of LCNEC patients in I–IIIA clinical stages who underwent resection. A total of 53 LCNEC (89%) and combined LCNEC (11%) patients in stages I–IIIA who underwent surgery with radical intent between 2002–2018 were included in the current study. Overall survival (OS) and time to recurrence (TTR) were estimated. Uni- and multivariable analyses were conducted using Cox-regression model. Patients were treated with surgery alone (51%), surgery with radiochemotherapy (4%), with radiotherapy (2%), with adjuvant chemotherapy (41%), or with neoadjuvant chemotherapy (2%). The median (95% Confidence Interval (CI)) OS and TTR was 52 months (20.1–102.1 months) and 20 months (7.0–75.6 months), respectively. Patients treated in clinical stage I showed better OS than patients in stages II–IIIA (p = 0.008). Patients with R0 resection margin (negative margin, no tumor at the margin) and without lymph node metastasis had significantly better TTR. In the multivariate analysis, age was an independent factor influencing OS. Recurrence within 1 year was noted in more than half cases of LCNEC. R0 resection margin and N0 status (no lymph node metastasis) were factors improving TTR. Age >64 years was observed as a main independent factor influencing OS.

Outcomes for Surgery in Large Cell Lung Neuroendocrine Cancer

INTRODUCTION

There are limited small, single-institution observational studies examining the role of surgery in large cell neuroendocrine cancer (LCNEC). We investigated the outcomes of surgery for stage I to IIIA LCNEC by using the National Cancer Database.

METHODS

Patients with stage I to IIIA LCNEC were identified in the National Cancer Database (2004-2015) and grouped by treatment: definitive chemoradiation versus surgery. Overall survival, by stage, was the primary outcome. Outcomes of surgical patients were also compared with those of patients with SCLC or other non-small cell histotypes.

RESULTS

A total of 6092 patients met the criteria: 96%, 94%, 75%, and 62% of patients received an operation for stage I, II, IIIA, and cN2 disease, respectively. Complete resection was achieved in at least 85% of patients. The 5-year survival rates for patients undergoing an operation for stage I and II LCNEC were 50% and 45%, respectively. Surgical patients with stage IIIA and N2 disease had 36% and 32% 5-year survival rates, respectively. When compared with stereotactic body radiation in stage I disease and chemoradiation in patients with stage II to IIIA disease, surgery was associated with a survival benefit. Patients with LCNEC who underwent an operation generally experienced worse survival by stage than did those with adenocarcinoma but experienced improved survival compared with patients with SCLC. Perioperative chemotherapy was associated with improved survival for pathologic stage II to IIIA disease.

CONCLUSIONS

Surgery is associated with reasonable outcomes for stage I to IIA LCNEC, although survival is generally worse than for adenocarcinoma. Surgery should be offered to medically fit patients with both early and locally advanced LCNEC, with guideline-concordant induction or adjuvant therapy.

Large-Cell Neuroendocrine Carcinoma of the Lung

BACKGROUND

Large-cell neuroendocrine carcinoma (LCNEC) of the lung displays morphologic and immunohistochemical characteristics common to neuroendocrine tumors and morphologic features of large-cell carcinomas. Because surgical resection of LCNEC in many series has been described with 5-year actuarial survival that is far worse than that reported for other histologic variants of non-small-cell lung cancer (NSCLC), considerable debate has emerged as to whether these tumors should be classified and treated as NSCLC or small-cell lung cancer.

METHODS

The initial evaluation and diagnosis, tumor classification, surgical treatment, results of therapy, and long-term prognosis of patients with LCNEC based on our experience are discussed, and a review of the literature is presented.

RESULTS

Patients with LCNEC are more likely to develop recurrent lung cancer and have shorter actuarial survival than patients with other histologic types of NSCLC, even in those with stage I disease.

CONCLUSIONS

Accurate differentiation of LCNEC from other types of NSCLC is important because it identifies those patients at highest risk for developing recurrent disease. Efforts to identify effective adjuvant therapies are needed to improve treatment outcomes with this aggressive type of lung cancer.

Adjuvant Chemotherapy Does Not Confer Superior Survival in Patients With Atypical Carcinoid Tumors

BACKGROUND

Although the use of adjuvant chemotherapy in patients with pathologically node-positive (pN+) atypical carcinoid tumor of the lung is an accepted practice, controversy exists about its use in pathologically node-negative (pN0) patients. Our aim was to determine whether a survival advantage exists in patients receiving chemotherapy postoperatively for pN0 or pN+ atypical carcinoid tumors of the lung.

METHODS

Adult patients treated with lobectomy or pneumonectomy for pulmonary atypical carcinoid tumor were identified using the National Cancer Data Base, 2006 to 2011. Propensity scoring (4:1 nearest neighbor algorithm) and survival analysis were used to examine the association between adjuvant chemotherapy and pN+ versus pN0 atypical carcinoid tumors.

RESULTS

Of the total 581 patients identified with a diagnosis of atypical carcinoid of the lung, 363 (62.5%) were found to be node negative at the time of operation and 218 (37.5%) had node-positive disease. Adjuvant chemotherapy was used in 15 patients (4.1%) with pN0 disease and 89 patients (40.8%) with pN+ disease. Unadjusted survival, at 12 and 60 months, was similar between pN+ patients who were treated with adjuvant chemotherapy versus patients who received operation alone (adjuvant chemotherapy: 98.9% at 12 months and 47.9% at 60 months versus operation alone: 98.4% and 12 months and 67.1% at 60 months, p = 0.46) and for propensity-matched pN0 (adjuvant chemotherapy: 86.7% at 12 months and 73.3% at 60 months versus operation alone: 87.9% at 12 months and 72.3% at 60 months, p = 0.54).

CONCLUSIONS

In a national-level analysis, the use of adjuvant chemotherapy postoperatively in patients with pN+ and pN0 disease conferred no survival advantage; further study is needed to determine proper chemotherapy use for these patients.

PI3K/AKT/mTOR pathway in pulmonary carcinoid tumours

The present study examined the expression of mammalian target of rapamycin (mTOR) and mutations in the phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway in 54 patients with typical carcinoid tumours (TC) or atypical carcinoid tumours (AC). In total, 54 bronchopulmonary neuroendocrine tumour (NET) surgical specimens, consisting of 17 TC, 8 AC, 17 large-cell neuroendocrine carcinoma (LCNEC), and 12 small-cell lung carcinoma (SCLC) samples, were tested for mTOR by immunohistochemistry, and 104 exon sites were tested in the PI3K/AKT/mTOR pathway by nested polymerase chain reaction. It was found that the positive rates for mTOR expression in TC/AC and LCNEC/SCLC were 60 (15/25) and 55.2% (16/29), respectively. In total, 4 missense mutations were found in 3 patients with TC/AC, including mutations in exon 48 of mTOR (c.6667C>T), exon 21 of tuberous sclerosis complex (TSC) 1 (c.2765G>A), and exons 12 (c.1265C>T) and 19 (c.2148C>T) of TSC2. To the best of our knowledge, mutations in exon 48 of mTOR and exon 21 of TSC1 have not been previously reported. Tissues from patients with single mutations exhibited strong positive mTOR immunohistochemical staining, and tissues from patients with double mutations were weakly positive. The same mutations were not observed in SCLC or LCNEC. In conclusion, gene mutations were observed and an association between the gene mutations and mTOR expression were indicated in the PI3K/AKT/mTOR pathway in TC/AC tumours. Those mutations may be driver genes and treatment targets.

The Antiproliferative Role of Lanreotide in Controlling Growth of Neuroendocrine Tumors: A Systematic Review

BACKGROUND

Neuroendocrine tumors (NETs) are a heterogeneous group of tumors, with >50% of cases involving the gastrointestinal system or pancreas. Somatostatin analogs (SSAs) are used for treating NET-related secretory syndromes and, more recently, for their antiproliferative effects. We conducted a systematic review of published literature on the antiproliferative efficacy and safety of the SSA lanreotide Autogel in the management of NETs to gain a fuller understanding of the evidence and identify future areas of research.

METHODS

Searches were conducted in PubMed up to March 16, 2016, and in the proceedings of four congresses from 2013 to 2016.

RESULTS

Screening of 1,132 publications identified in the searches found 40 relevant publications, including 27 full-length publications and 13 congress abstracts. Twenty-four of these publications reported antiproliferative efficacy data for lanreotide Autogel. The CLARINET study showed that 120 mg lanreotide Autogel every 4 weeks improves progression-free survival (PFS) in patients with gastroenteropancreatic (GEP)-NETs, with grade 1 or grade 2 (Ki-67 <10%) disease, providing class I evidence of its antiproliferative effects. The CLARINET open-label extension study reported a median PFS of 32.8 months with lanreotide Autogel. Other smaller studies generally support CLARINET.

CONCLUSION

Current clinical evidence shows that lanreotide Autogel has good antiproliferative activity with favorable safety and tolerability in patients with GEP-NETs, suggesting it should be considered as an early first-line treatment in this population. Further studies are needed to assess the potential benefits of higher doses and the use of lanreotide Autogel in combination therapy and as maintenance therapy in the absence of disease progression following other therapies. The Oncologist 2017;22:272-285 IMPLICATIONS FOR PRACTICE: This review presents the current clinical evidence for the antiproliferative activity of lanreotide Autogel in patients with midgut or pancreatic neuroendocrine tumors (NETs) and shows its effectiveness, safety, and tolerability in these patient populations. By systematically presenting all the clinical evidence, the review adds to existing publications by discussing results in a broad range of settings. The review also indicates future directions for investigation of the use of lanreotide Autogel in NETs originating in other locations, in combination therapy, or as maintenance therapy in progressive disease.

Patient characteristics, treatment and survival in pulmonary carcinoid tumours: an analysis from the UK National Lung Cancer Audit

OBJECTIVES

Pulmonary carcinoid (PC) is a rare tumour with good prognosis following surgical resection. However, little is known regarding patient characteristics and use of other treatments modalities. Our objective was to review patient characteristics, treatment and survival for patients with PC and contrast these results with other forms of non-small cell lung cancer (NSCLC).

SETTING

Audit data from UK National Lung Cancer Audit (NLCA) 2008-2013.

PARTICIPANTS

184 906 lung cancer cases were submitted to the NLCA.

OUTCOME MEASURES

Primary outcome-survival rates between PC and NSCLC. Secondary outcome-differences in performance status, lung function and treatment modality between PC and NSCLC.

RESULTS

PC histology was recorded in 1341 (0.73%) patients and non-carcinoid NSCLC histology in 162 959 (87.4%) cases. 91% of patients with PC had good performance status (Eastern Cooperative Oncology Group (ECOG) 0-1), compared with only 53% of NSCLC. 66% of PC had localised disease. Of all PC cases, 77% were treated with surgery, 6.2% received chemotherapy and 3.6% received radiotherapy, with the remainder treated with best supportive care. Overall 1-year and 3-year survival rates for PC were 92% and 84.7%, respectively. In contrast, 1-year and 3-year survival rates for NSCLC were 36.2% and 15.6%, However, 3-year survival for PC markedly decreased with worsening performance status and advanced disease to 23.8% for performance status ECOG 3-4 and 33.6% for stage IV disease.

CONCLUSIONS

In contrast to other forms of NSCLC, the majority of patients with PC present with good performance status, preserved lung function and early stage disease amenable to surgical resection. However, 1 in 5 patients with PC has metastatic disease which is associated with poor prognosis, as is poor performance status at presentation. We believe these data will help clinicians provide accurate prognostic predictions stratified according to patient characteristics at presentation, as well as guide future clinical trials.

Carcinoid tumours of the lung and the 'PEPPS' approach: evaluation of preoperative bronchoscopic tumour debulking as preparation for subsequent parenchyma-sparing surgery

BACKGROUND

Preoperative bronchoscopic tumour ablation has been suggested as a beneficial treatment for bronchopulmonary carcinoid tumours, although data regarding its effects and long-term outcome are lacking.

METHODS

In our case-matched cohort study with 208 patients with bronchopulmonary carcinoid tumours we investigated the role of preoperative bronchoscopic interventions before subsequent surgery and analysed the safety of this Procedure of Endobronchial Preparation for Parenchyma-sparing Surgery (PEPPS) based on metastasis and recurrence rates as well as survival data from 1991 to 2010. The subsequent surgery was classified into parenchyma-sparing procedures and classical lobectomies, bilobectomies and pneumonectomies. Data were obtained from the tumour registry and medical reports. Outcomes were the frequency of parenchyma-sparing surgery after bronchoscopic treatment as well as rates of metastasis, recurrence and survival.

RESULTS

132 of 208 carcinoids were located centrally. Among them, 77 patients could be recanalised preoperatively. After bronchoscopic preparation, the rate of subsequent parenchyma-sparing surgery methods was higher (p=0.021). The effect was measured by the number of segments removed. The 10-year survival rate was 89% (typical carcinoids) and 68% (atypical carcinoids), respectively. After applying PEPPS, long-term survival was slightly higher (p=0.23). Metastasis and recurrence rates showed no relevant differences between the bronchoscopically treated or non-treated groups, or between the two types of surgery classes or between the PEPPS and non-PEPPS groups.

CONCLUSIONS

After preoperative bronchoscopic treatment, parenchyma-sparing surgery techniques can be applied more frequently. Furthermore, we detected no negative effects after PEPPS based on metastasis, recurrence and survival rates.

Alterations in the expression of p53, KLF4, and p21 in neuroendocrine lung tumors

CONTEXT

Neuroendocrine lung neoplasms are a heterogeneous group of tumors with different clinical behavior and prognosis.

OBJECTIVES

To evaluate the expression of p53, KLF4, and p21 in neuroendocrine lung neoplasms and to analyze the influence that expression has on the prognosis of those tumors.

DESIGN

All neuroendocrine lung neoplasms (N = 109) resected in our institution were reviewed, with the collection of histologic slides and paraffin blocks of 47 typical carcinoids (43%), 9 atypical carcinoids (8%), 35 large cell neuroendocrine carcinomas (32%), and 18 small cell lung carcinomas (17%), as well as 10 tumorlets (100%). Four tissue microarrays were performed. Follow-up was assessed in all cases (119 of 119; 100%).

RESULTS

p53 protein immunostaining results were negative in both the tumorlets and typical carcinoids and were overexpressed in 11% (1 of 9) of the atypical carcinoids and in 68% (36 of 53) of the carcinomas. KLF4 results were positive in all tumorlets (10 of 10; 100%), 32% (15 of 47) of the typical carcinoids, 44% (4 of 9) of the atypical carcinoids, and 62% (33 of 53) of the carcinomas. p21 expression did not differ among the groups. The lack of KLF4 and p21 expression was associated with an accumulation of aggressive features in typical carcinoids (P = .04 and P = .004, respectively, Fisher exact test).

CONCLUSIONS

p53, KLF4, and p21 showed altered expression patterns in pulmonary neuroendocrine neoplasms. Lack of KLF4 and p21 expression was associated with accumulation of aggressive features in typical carcinoids.

Role of 68Ga-DOTATOC PET/CT in initial evaluation of patients with suspected bronchopulmonary carcinoid

PURPOSE

The objective of this study was to evaluate the role of (68)Ga-DOTATOC positron emission tomography (PET)/CT scan in patients with suspected pulmonary carcinoid tumour and to compare its results with (18)F-fluorodeoxyglucose (FDG) PET/CT scan.

METHODS

In this prospective study, 32 patients (age 34.22 ± 12.03 years; 53.1 % female) with clinical suspicion of bronchopulmonary carcinoid were evaluated with (68)Ga-DOTATOC PET/CT and (18)F-FDG PET/CT. The two imaging modalities were compared, considering the tissue diagnosis as the reference standard.

RESULTS

Based on the reference standard 26 cases were carcinoid tumours [21 typical carcinoids (TC) and 5 atypical carcinoids (AC)] and 6 cases were non-carcinoid tumours. The sensitivity, specificity and accuracy of (68)Ga-DOTATOC PET/CT in the diagnosis of pulmonary carcinoid tumour were 96.15, 100 and 96.87 % respectively, whereas those of (18)F-FDG PET/CT were 78.26, 11.1 and 59.37 % respectively. The maximum standardised uptake value (SUV max) of TC on (68)Ga-DOTATOC PET/CT scan ranged from 3.58 to 55, while that of AC ranged from 1.1 to 32.5. (18)F-FDG PET/CT was true-positive in all cases of AC and false-negative in eight cases of TC (sensitivity for TC 61.9 % and for AC 100 %).

CONCLUSION

(68)Ga-DOTATOC PET/CT is a useful imaging investigation for the evaluation of pulmonary carcinoids. (18)F-FDG PET/CT scan suffers from low sensitivity and specificity in differentiating the pulmonary carcinoids from other tumours.

Pure bronchoplastic resections of the bronchus without pulmonary resection for endobronchial carcinoid tumours

OBJECTIVES

Bronchopulmonary carcinoid tumours are relatively uncommon primary lung neoplasms. A small proportion of these lesions are predominantly endobronchial and do not extend beyond the bronchial wall. Endoscopic resection can be performed, but carries around a one in three risk of local recurrence and, therefore, mandates long-term surveillance. An alternative is complete surgical resection via bronchoplastic resection. We present our experience of surgical resection in patients with endobronchial carcinoids.

METHODS

From 2000 to 2010, 13 patients (age 45±16 years, 10 males) underwent pure bronchoplastic resection, including systematic nodal dissection, for endobronchial carcinoid tumours, without the resection of lung parenchyma.

RESULTS

There was no significant operative morbidity or mortality. This is a retrospective review of a consecutive case series. The last follow-up for all patients was obtained in 2011. The mean maximum tumour size was 18±8 mm. No lymph node invasion was observed. The median follow-up was 6.3±3.3 years, with no regional recurrence. In 1 case, a tumourlet was identified at 5 years in the contralateral airway and viewed as a metachronous new lesion.

CONCLUSIONS

Bronchial sleeve resection is a safe procedure for suitably located endobronchial carcinoid tumours. Endoscopic resection should be reserved for patients who decline, or are unfit, for surgery.

Lung parenchymal invasion in pulmonary carcinoid tumor: an important histologic feature suggesting the diagnosis of atypical carcinoid and poor prognosis

The majority of previous studies on pulmonary carcinoid tumor have usually focused on clinical behavior or outcome, seldom considering histopathologic features. We retrospectively collected 63 cases of resected pulmonary carcinoid tumors from 1995 to 2011 at Samsung Medical Center, Seoul, Korea. The clinical and pathological features were correlated and survival analyses were performed. Forty cases (63.5%) were classified as typical carcinoid (TC) and 23 cases (36.5%) were classified as atypical carcinoid (AC) according to WHO classification criteria. AC patients showed a higher frequency of current smoking status and a higher stage of the tumor by the American Joint Committee on Cancer than TC patients. The disease was associated with death and recurrence in five and seven patients, respectively, with almost all of the associations found in AC patients. The five-year survival rate of TC and AC were 100% and 83.5%, respectively, with AC showing poorer prognosis than TC in overall survival (OS) and disease free survival (DFS) (p=0.005 and p=0.002). Lung parenchymal invasion was observed more commonly in AC than in TC (39.1% vs 12.5%, p=0.01) and was a poor prognostic factor in OS and DFS. Rosette-like arrangements were found only in six cases of AC, while abundant basophilic cytoplasm mimicking paraganglioma and ossification were found only in TC. Through the comprehensive study of pulmonary carcinoid tumor in Korea, we suggest that lung parenchymal invasion could be a useful histologic feature to suspect the diagnosis of AC in daily practice as well as to predict the prognosis of carcinoid tumor.

Phosphatidylinositol-3-kinase α catalytic subunit gene somatic mutations in bronchopulmonary neuroendocrine tumours

Bronchopulmonary neuroendocrine tumours (BP-NETs) comprise a large spectrum of tumours including typical carcinoids (TCs), atypical carcinoids (ACs), large-cell neuroendocrine carcinomas (LCNECs) and small-cell lung carcinomas (SCLCs) that exhibit considerably different biological aggressiveness and clinical behaviours. The phosphatidylinositol-3-kinase α catalytic subunit (PIK3CA) gene is known to be involved in the pathogenesis of several types of human cancers through gene amplification, deletions or somatic missense mutations within the helical and catalytic domains. However, the PIK3CA gene status in BP-NETs has yet to be explored. This study aimed to investigate the PIK3CA gene status in a large series of BP-NETs by direct gene sequencing and to analyse its correlation with the main clinicopathological parameters. To the best of our knowledge, we demonstrated for the first time a high frequency of somatic missense mutations (23.2%) in the PIK3CA gene in a series of 190 BP-NETs, including 75 TCs, 23 ACs, 17 LCNECs and 75 SCLCs. The frequency of the PIK3CA gene mutation in the kinase domain was higher (17.9%) than that in the helical domain (5.3%). When the mutational status of the PIK3CA gene was compared with the main clinical and pathological characteristics of the BP-NET patients, we found a significant association between PIK3CA gene mutations and BP-NET histology (p=0.011). Interestingly, the frequency of PIK3CA gene mutations increased with the biological aggressiveness of all BP-NETs, except LCNECs. In conclusion, our results suggest that PIK3CA gene mutations may play a key role in tumourigenesis and aggressiveness of BP-NETs. The PIK3CA gene may represent a favourable candidate for an effective therapeutic strategy in the treatment of patients with BP-NETs.

Utility of ¹¹¹indium-pentetreotide scintigraphy in patients with neuroendocrine tumors

BACKGROUND

Neuroendocrine (NE) tumors pose a diagnostic challenge with the need to utilize a combination of biochemical analysis, standard cross-sectional imaging, and more recently, nuclear medicine scans such as (111)indium-pentetreotide scintigraphy (somatostatin receptor scintigraphy, SRS; OctreoScan, Covidien Imaging Solutions, Hazelwood, MO). In this study we sought to evaluate the clinical utility of scintigraphy in the diagnosis and management of patients with NE tumors at a major university hospital.

METHODS

A retrospective chart review was performed on all patients who underwent both (111)indium-pentetreotide scintigraphy and computed tomography/magnetic resonance imaging (CT/MRI) at a single institution between February 2001 and July 2008. Charts were reviewed for patient demographics, symptoms of NE disease, and results of biochemical testing, imaging studies, histopathologic diagnosis, and medical and/or surgical management.

RESULTS

One hundred forty-five patients received (111)indium-pentetreotide scintigraphy (SRS) and concurrent cross-sectional imaging (CT/MRI) over the 7-year period studied. In the evaluation of primary disease, 60 % of tumors were localized by anatomic imaging, significantly greater than the 15 % detection rate achieved by SRS. In the evaluation of recurrent disease, 61 % of NE tumors were localized by cross-sectional imaging, significantly greater than the 31 % detection rate of SRS. Scintigraphy identified disease foci not seen on CT/MRI in just 8 of 74 of the cohort with evidence of disease and only altered the surgical management in 3 of 74 cases.

CONCLUSIONS

Cross-sectional CT/MRI imaging is sufficient for the localization of NE tumors. (111)Indium-pentetreotide scintigraphy does not significantly alter the surgical management of patients with NE tumors, and we suggest that it be selectively reserved for patients with disease that is occult to cross-sectional imaging.

Diagnostic and prognostic significance of the alternatively spliced ACTN4 variant in high-grade neuroendocrine pulmonary tumours

BACKGROUND

High-grade neuroendocrine tumours (HGNTs) of the lung manifest a wide spectrum of clinical behaviour, but no method for predicting their outcome has been established.

MATERIALS AND METHODS

We newly established a monoclonal antibody specifically recognizing the product of the alternatively spliced ACTN4 transcript (namely, variant actinin-4), and used it to examine the expression of variant actinin-4 immunohistochemically in a total of 609 surgical specimens of various histological subtypes of lung cancer.

RESULTS

Variant actinin-4 was expressed in 55% (96/176) of HGNTs, but in only 0.8% (3/378) of non-neuroendocrine (NE) lung cancers. The expression of variant actinin-4 was significantly associated with poorer overall survival in HGNT patients (P=0.00021, log-rank test). Multivariate analysis using the Cox proportional hazards model showed that the expression of variant actinin-4 was the most significant independent negative predictor of survival in HGNT patients (hazard ratio (HR), 2.15; P=0.00113) after the presence of lymph node metastasis (HR, 2.25; P=0.00023).

CONCLUSIONS

The expression of variant actinin-4 is an independent prognostic factor for patients with HGNTs. This protein has a high affinity for filamentous actin polymers and likely promotes aggressive behaviour of cancer cells. The present clinical findings clearly support this notion.

Treatment of pulmonary neuroendocrine tumours: state of the art and future developments

The current classification of pulmonary neuroendocrine tumours includes four subtypes: low-grade typical carcinoid tumour (TC), intermediate-grade atypical carcinoid tumour (AC), and two high-grade malignancies: large cell neuroendocrine carcinoma and small cell lung cancer (SCLC). Unfortunately, with the exclusion of SCLC, no large phase II and III trials for pulmonary neuroendocrine tumours have been published. Thus, several treatment approaches are available for their treatment but none of them has been validated in appropriately designed and adequately sized clinical trials. The main problem of the published studies is that they include neuroendocrine tumours from various sites of origin with different clinical behaviour. It is important that future studies consider these tumours separately. In this regard, increased awareness and referral of these patients to tertiary centres, in which a multidisciplinary management is available, may be of value. The aim of this review is to evaluate the state of the art and discuss future developments in the management of pulmonary neuroendocrine tumours excluding SCLC which we consider should be addressed in a different issue.

Immunohistochemical studies of pulmonary large cell neuroendocrine carcinoma: a possible association between staining patterns with neuroendocrine markers and tumor response to chemotherapy

OBJECTIVE

Pulmonary large cell neuroendocrine carcinoma is a rare high-grade malignant tumor. Because large cell neuroendocrine carcinoma is rare, the optimal treatment, including perioperative chemotherapy, has not been defined. We retrospectively analyzed the correlation among the effectiveness of perioperative chemotherapy in treating large cell neuroendocrine carcinoma, pathologic stage, and immunoreactivity to neuroendocrine markers.

METHODS

A total of 63 patients with pulmonary large cell neuroendocrine carcinoma undergoing surgical resection from 2001 to 2009 were included. The resected tumors were immunohistochemically stained with the 3 neuroendocrine markers synaptophysin, chromogranin A, and neural cell adhesion molecule. We categorized patients who were positive for all 3 markers as the triple-positive group and those who were negative for 1 or 2 markers as the non-triple-positive group.

RESULTS

Perioperative chemotherapy resulted in better overall survival than surgery alone (P = .042). Multivariate analysis of survival revealed that perioperative chemotherapy was a significant independent prognostic factor (hazard ratio, 0.323; 95% confidence interval, 0.112-0.934; P = .0371). Among the patients who received perioperative chemotherapy, the non-triple-positive group had a significantly greater 5-year survival rate than the triple-positive group (P = .0216). Moreover, among the non-triple-positive group, a significantly greater 5-year survival rate was observed for the patients who underwent surgery with chemotherapy than for those who underwent surgery without chemotherapy (P = .0081). In contrast, no difference was found in 5-year survival between patients with chemotherapy and those without chemotherapy when the tumors were triple positive.

CONCLUSIONS

Our results suggest that perioperative chemotherapy might benefit the survival of patients with pulmonary large cell neuroendocrine carcinoma, in particular when the tumors are not immunoreactive to all 3 neuroendocrine markers.

Fast-growing large cell neuroendocrine carcinoma of mediastinum

Neuroendocrine carcinomas combine a heterogeneous group of tumors occurring in lungs on a rare occasion, and in some cases, they appear to have extraordinary quick growth and extrapulmonary localization. In this case we present a 42-year-old patient who underwent a right upper lobectomy for emphysema, and 6 months later, the tumor developed again into a giant neuroendocrine carcinoma of the mediastinum.

Expression of p-AKT and p-mTOR in a large series of bronchopulmonary neuroendocrine tumors

Bronchopulmonary neuroendocrine tumors (BP-NETs) are separated into four subgroups: typical carcinoid tumor (TC), atypical carcinoid tumor (AC), large-cell neuroendocrine carcinoma (LCNEC) and small-cell lung carcinoma (SCLC). The signaling pathway involving AKT/mammalian target of rapamycin (mTOR) is crucial to the regulation of cell growth, proliferation and survival, and is frequently activated in human cancers. Consequently, mTOR is considered an attractive target for anticancer agents. The present study aimed to evaluate the expression of phosphorylated AKT and mTOR in a series of BP-NETs, and to analyze the correlations with clinicopathological parameters. p-AKT and p-mTOR levels were determined by immunohistochemistry in a series of 210 BP-NETs, including 85 SCLCs, 17 LCNECs, 26 ACs, 75 TCs and 7 tumorlets. Higher p-AKT and p-mTOR expression levels were identified in the majority of tumorlets and carcinoids in comparison to the LCNECs (P=0.0001) and SCLCs (P=0.0002). Furthermore, a significant association was observed between p-mTOR expression and tumor size (T) in SCLCs (P=0.04) and LCNECs (P=0.03): T3-T4 tumors exhibited significantly lower p-mTOR expression compared to T1-T2 tumors. In conclusion, most of the BP-NETs examined in this study expressed p-AKT and p-mTOR, suggesting that the AKT/mTOR pathway plays an important role in these tumors. Additionally, our results confirm that low- to intermediate-grade tumors are more closely associated to each other than to high-grade tumors, despite sharing common classification and a common origin from neuroendocrine cells. These findings improve our knowledge of the biological characterization of these tumors and indicate new therapeutic opportunities for the treatment of BP-NETs.

Neuroendocrine carcinoma of unknown primary: a systematic review of the literature and a comparative study with other neuroendocrine tumors

INTRODUCTION

Neuroendocrine carcinomas of unknown primary (NCUP) represent a specific subset with relatively favorable prognosis. Data on biology, management and outcome of NCUP patients have not been systematically reviewed neither compared to those of neuroendocrine tumors of known primary.

PATIENTS AND METHODS

We systematically reviewed all publications studying neuroendocrine CUP patients and presented a single center retrospective patient series. In addition, we analyzed and specified the similarities and/or differences between NCUP and other neuroendocrine malignancies.

RESULTS

Five hundred patients with NCUP constituted a heterogeneous cohort in terms of histology, grade, anatomic site and tumor biology in published series and were managed mostly with platinum-based regimens. Among 294 patients with available outcome data, a median survival of 15.5 months (range 11.6-40) was observed. Comparative analysis with neuroendocrine solid tumors (NET) revealed that poorly-differentiated NCUP share an aggressive natural history and a dismal prognosis similar to high grade pulmonary and extrapulmonary neuroendocrine carcinomas (Large Cell Neuroendocrine bronchial Carcinomas, LCNEC and poorly differentiated gastroenteropancreatic tumors, GEP-NET). Well differentiated NCUP reveal a more indolent course with a survival range resembling that of typical and atypical pulmonary carcinoids, well differentiated gastrointestinal NETs and limited small cell lung carcinomas.

CONCLUSION

No evidence for distinct biology or outcome of NCUP patients emerged when histological grade was matched for known primary NETs. The high heterogeneity of the NCUP subgroup limits the potential for identification of reliable prognosticators and hinders development of novel targeted therapies.

Symptoms and diagnostics of lung neuroendocrine tumors

Pulmonary neuroendocrine tumors comprise 20% of all lung cancers. They are separated into 4 subgroups: typical carcinoid tumor, atypical carcinoid tumor, large-cell neuroendocrine carcinoma, and small-cell lung carcinoma. The major symptoms present in 60% of patients are cough, hemoptysis, and obstructive pneumonia. They may also exhibit hormonally related symptoms e.g. carcinoid syndrome. Small cell lung cancer is the most common subgroup, with rapid progression, aggressive metastatic potential and the worst prognosis. Large cell neuroendocrine carcinoma is rare but also has a poor prognosis. Typical carcinoid may be accompanied with hormone related symptoms and has the best prognosis; atypical one on the contrary may cause lymph node and distant metastases in half of the cases. Elevated plasma levels of chromogranin-A are present in majority of pulmonary neuroendocrine tumors and act as tumor marker. The mainstay of treatment is radical surgery if possible. In locally advanced or metastatic disease combination chemotherapy and somatostatin-analogues may have beneficial effect. This review focuses on the general features, and current diagnostic options of pulmonary neuroendocrine tumors. Orv. Hetil., 2011, 152, 366–370.

Histologic features of low- and intermediate-grade neuroendocrine carcinoma (typical and atypical carcinoid tumors) of the lung

BACKGROUND

Determining the differential diagnosis between typical (TCs) and atypical carcinoid tumors (ACs) is imperative, as the distinction between TCs and ACs is currently based on histologic criteria that are not always correlated with the unfavorable clinical outcomes.

PATIENTS AND METHODS

We conducted a retrospective study of patients who were diagnosed with carcinoid tumors between 1990 and 2005 at M. D. Anderson Cancer Center. We reviewed the slides for the following pathologic features: infiltrative growth; pleural, blood, or lymphatic vessel invasion; tumor stroma; presence of active fibroblastic proliferation; chromatin pattern; presence of nucleolus; and nuclear pleomorphism. We also evaluated the necrotic patterns. Finally, we evaluated three methods for calculating the number of mitoses: randomly selected, the most mitotically active in 10 high-power fields (HPFs), or overall mean mitotic count.

RESULTS

Our cohort consisted of 80 patients (68 with TCs and 12 with ACs). Older age (P=0.002), pathologic stage III or IV disease (P=0.04), active fibroblastic proliferation (P=0.041), and comedo-like necrosis (P=0.001) were significantly associated with tumor recurrence or patient's death. Among the three mitotic counting methods, the overall mean number of mitoses was significantly correlated with recurrence-free survival (P<0.0001). Our criteria for distinguishing AC from TC included the presence of comedo-like necrosis and/or an overall mean number of mitoses ≥0.2/HPF.

CONCLUSIONS

Using an overall mean number in counting mitoses and detecting comedo-like necrosis is important for classifying lung carcinoid tumors.

Partitioning of bronchopulmonary carcinoids in two different prognostic categories by ki-67 score

INTRODUCTION

Histological distinction between typical and atypical bronchopulmonary carcinoids is based on mitotic activity and necrosis. Regardless of these two parameters, outcome after surgery is often unpredictable. In this study the prognostic value of different clinico-pathological factors was retrospectively analyzed in a large series of patients with bronchopulmonary carcinoid.

MATERIALS AND METHODS

The long-term post-surgical outcome of 106 radically treated patients affected by bronchopulmonary carcinoid from two Italian centers was correlated with tumor characteristics assessed by combining conventional histology with a panel of immunohistochemical markers of neuroendocrine differentiation (chromogranin-A, NSE) and proliferation activity (Ki-67 score).

RESULTS

Carcinoids were assessed as typical (TC = 75; 70.8%) and atypical (AC = 31; 29.2%). Mean follow-up was 8.3 years (range: 0-20; median: 8.0). All cases expressed neuroendocrine markers. At univariate analysis, tumor recurrence [14/75 TC (18.7%), 15/31 AC (48.4%)] correlated with carcinoid histotype (P = 0.003), tumor size (P = 0.012), mitotic index (P = 0.044), Ki-67 score (P < 0.0001), and synchronous node metastasis (P = 0.037). Of these, Cox multivariate analysis confirmed only Ki-67 score as independent predictor of disease recurrence (P = 0.009). The best cut-off for Ki-67 score (calculated by ROC curves) discriminating recurrent vs non-recurrent disease was 4% (sensitivity 79.3%; specificity 83.8%; area under the curve 0.85). By stratifying patients according to this cut-off, a significantly different disease-free survival was found (log-rank test P < 0.0001).

CONCLUSION

Ki-67 score accurately separates bronchopulmonary carcinoids in two well-distinct histo-prognostic categories. Ki-67 score predicts the patients outcome better than mitotic count, histotype, and tumor stage and it is therefore helpful in establishing the appropriate follow-up.

Klotho is a novel biomarker for good survival in resected large cell neuroendocrine carcinoma of the lung

BACKGROUND

In terms of prognosis, large cell neuroendocrine carcinoma (LCNEC) differs distinctively from other non-small cell lung cancers, with the prognosis of LCNEC being poor, even for early-stage disease. Improvements in survival require a biomarker capable of defining a subset of patients destined to do poorly so that these patients can be targeted for additional therapies, including chemotherapy. In this study, we focused on the Klotho gene, which is an anti-aging gene known to be a potential tumor suppressor. We investigated whether the immunohistochemical expression of Klotho can predict survival patients with resected LCNEC.

METHODS

The histological characteristics of patients receiving an initial diagnosis of LCNEC (n=30) at Tokyo Medical University Hospital were retrospectively reviewed, and multiple variables including stage, lymphangioinvasion, lymph node status and the expression of Klotho as identified using an immunohistochemical analysis, were assessed.

RESULTS

Immunostaining for Klotho was mostly cytoplasmic, and Klotho expression was seen in 10 patients (33.3%) but not in 20 patients (66.7%). The expression of Klotho was significantly associated with a good outcome of resected patients with LCNEC and Klotho(-) was associated with increased LCNEC risk by multivariate analysis (hazard ratio 4.92, 95% confidence interval 1.04-23.24, p=0.044). Neither lymph node status nor lymphangioinvasion were significantly associated with a poor survival. However, among patients without lymph node metastasis or angioinvasion, the survival benefit of Klotho expression in the primary tumor was significantly higher, compared with that of patients without Klotho expression.

CONCLUSION

Klotho staining provides a new biomarker for a good outcome in patients with LCNEC, especially among patients without lymph node metastasis or lymphangioinvasion.

Multimodal management of neuroendocrine liver metastases

BACKGROUND

The incidence of neuroendocrine tumours (NET) has increased over the past three decades. Hepatic metastases which occur in up to 75% of NET patients significantly worsen their prognosis. New imaging techniques with increasing sensitivity enabling tumour detection at an early stage have been developed. The treatment encompasses a panel of surgical and non-surgical modalities.

METHODS

This article reviews the published literature related to management of hepatic neuroendocrine metastases.

RESULTS

Abdominal computer tomography, magnetic resonance tomography and somatostatin receptor scintigraphy are widely accepted imaging modalities. Hepatic resection is the only potentially curative treatment. Liver transplantation is justified in highly selected patients. Liver-directed interventional techniques and locally ablative measures offer effective palliation. Promising novel therapeutic options offering targeted approaches are under evaluation.

CONCLUSIONS

The treatment of neuroendocrine liver metastases still needs to be standardized. Management in centres of expertise should be strongly encouraged in order to enable a multidisciplinary approach and personalized treatment. Development of molecular prognostic factors to select treatment according to patient risk should be attempted.

ERCC1 and Ki67 in small cell lung carcinoma and other neuroendocrine tumors of the lung: distribution and impact on survival

BACKGROUND

Excision repair cross-complementation group 1 (ERCC1) is a key component of the platinum-DNA repair mechanism. Ki67 is associated with the clinical course of several malignancies. The associations of ERCC1 and Ki67, clinical features and survival in small cell lung carcinoma (SCLC), typical carcinoid (TC), atypical carcinoid (AC), and large cell neuroendocrine carcinoma (LCNEC) were determined.

MATERIALS AND METHODS

We included a consecutive series of 186 patients with SCLC treated with platinum-based chemotherapy and surgically treated patients with TC (n = 48), AC (n = 15) and LCNEC (n = 27). ERCC1 and Ki 67 were measured by immunohistochemistry and scored using published criteria.

RESULTS

The expression of ERCC1 was different among the different tumor types (p < 0.001). For patient with limited disease as well as extensive disease SCLC, no association of ERCC1 expression with survival was observed (p = 0.59). However, only 10% of SCLC tumors expressed ERCC1. For TC and AC, ERCC1 positive patients had better survival than ERCC1 negative patients. ERCC1 had no prognostic impact for LCNEC. A difference of the percentage of Ki67 LI was observed for the different tumor types (p < 0.001). The difference between TC and AC was significant (p = 0.02), as was the difference between low grade (TC+AC) and high grade NE (LCNEC + SCLC) (p < 0.001). For all included patients, a correlation between Ki67 and ERCC1 was observed (RSquare = 0.19, p < 0.001).

CONCLUSION

ERCC1 expression in SCLC treated with platinum-based chemotherapy has no impact on survival. High expression of ERCC1 in TC might represent a clue to the failure of platinum-based therapy in these patients. ERCC1 expression has prognostic impact in lung carcinoids. Ki 67 might be considered as a supplementary test to the histopatologic classification of NE tumors.

High-grade neuroendocrine carcinoma of the lung shows increased thymidylate synthase expression compared to other histotypes

BACKGROUND

Thymidylate synthase (TS) expression has been reported in various tumors, including non-small-cell lung carcinoma (NSCLC), but not in high-grade neuroendocrine (HGNE) carcinoma of the lung.

METHODS

We measured TS expression in surgically resected pulmonary tumors, comparing HGNE carcinomas of the lung (13 large-cell neuroendocrine carcinomas, 8 small-cell lung carcinomas) with squamous cell carcinoma and adenocarcinoma of the lung using laser-capture microdissection for tissue isolation, real-time polymerase chain reaction (PCR), and immunohistochemistry. We also measured TS mRNA expression in small-cell lung carcinoma (SCLC) and NSCLC cell lines using real-time PCR.

RESULTS

At both mRNA and protein levels, TS expression was significantly higher in squamous cell carcinoma compared to adenocarcinoma. Moreover, TS expression was significantly higher in HGNE carcinomas of the lung compared to squamous cell carcinoma. A significant correlation was found between mRNA and protein expression. TS mRNA expression in SCLC cell lines was significantly higher than in NSCLC cell lines.

CONCLUSIONS

TS expression was higher in HGNE carcinomas of the lung than in squamous cell carcinoma, which was higher than in adenocarcinoma. This information may be useful in predicting the effects of TS-inhibiting agents in patients with NSCLC and HGNE carcinomas of the lung.

Pulmonary neuroendocrine/carcinoid tumors: a review article

Neuroendocrine tumors are a unique malignant neoplasm that can arise from the respiratory tree. Although well-differentiated bronchial neuroendocrine tumors (also called carcinoid tumors) are reported to account for approximately 25% of all neuroendocrine tumors, they represent only 1% to 2% of all lung cancers. The epidemiology, clinical behavior, and treatment of neuroendocrine carcinoid tumors differ significantly from other lung malignancies. In this article, the recent data regarding these tumors were reviewed with attention to the treatment modalities used. Although conventional cytotoxic therapy has not been reported to demonstrate much promise in this entity over the past 4 decades, newer molecular targeted agents including those that targeted angiogenesis and the mammalian target of rapamycin (mTOR) pathway have shown encouraging results in early phase trials for advanced carcinoid tumors.

Multiple pulmonary atypical carcinoids presenting with long-standing Cushing syndrome masked by pulmonary tuberculosis

Pulmonary neuroendocrine tumors, especially small cell carcinoma and typical carcinoids, are the most common cause of ectopic Cushing syndrome (CS). Sometimes these adrenocorticotropic hormone (ACTH)-producing tumors are too small to localize, and it may take a long time to identify them. This report describes the case of a 27-year-old-man with CS. This CS was due to the ectopic ACTH produced by the pulmonary atypical carcinoids, which were recognized at the disseminated stage 5 years after the initial presentation of CS. Microscopically, multiple whitish nodules (up to 1.0 cm in diameter) of the wedge-resected lung were composed of small round cells appearing to be typical neuroendocrine but were diagnosed as atypical carcinoid, based on the findings of focal necrosis, high mitotic rates and multiple endolymphatic tumor emboli. Immunohistochemically, tumor cells robustly stained for ACTH. The delay of diagnosis is, in part, attributable to the pulmonary tuberculosis (one of the complications of hypercortisolism), because the pulmonary tuberculosis presented in the form of multiple nodules throughout the lung. In addition, this patient had a Crooke's cell hyperplasia of the pituitary gland, which represents the reactive change of corticotrophs exposed to the excess cortisol rather than neoplastic change leading to CS.

Neuroendocrine carcinomas of the lung: a critical analysis

Neuroendocrine carcinomas represent an important group of primary neoplasms in the lung. During the last decades, the nomenclature of these tumors has evolved and the current use of immunohistochemical and molecular biology studies have, to some extent, expanded the conventional view of these tumors. However, the primary diagnosis of most of these lesions is performed on limited biopsy specimens, which may not translate well when one is confronted with a nomenclature that is based on resected material. In addition, for some of these specific entities, some confusion and controversy apparently remain, allowing for the proliferations of different terms that, although they may be dismissed as "semantics," may have a role in interpretation, further subclassification, and, possibly, treatment. Herein we review current concepts regarding the classification of these neoplasms and the role of this classification in our daily practice and discuss how it may impact treatment.

Bronchopulmonary neuroendocrine tumors

Bronchopulmonary neuroendocrine tumors (BP-NETs) comprise approximately 20% of all lung cancers and represent a spectrum of tumors arising from neuroendocrine cells of the BP-epithelium. Although they share structural, morphological, immunohistochemical, and ultrastructural features, they are separated into 4 subgroups: typical carcinoid tumor (TC), atypical carcinoid tumor (AC), large-cell neuroendocrine carcinoma (LCNEC), and small-cell lung carcinoma (SCLC), which exhibit considerably different biological characteristics. The clinical presentation includes cough, hemoptysis, and obstructive pneumonia but varies depending on site, size, and growth pattern. Less than 5% of BP-NETs exhibit hormonally related symptoms such as carcinoid syndrome, Cushing, acromegaly, and SIADH. SCLC is the most common BP-NET, while LCNEC is rare, approximately 10% and < or =1%, respectively, of all lung cancers. Both SCLC and LCNEC progress rapidly, are aggressively metastatic, and exhibit a poor prognosis. The incidence of BP-carcinoids (TC and AC) in the US was 1.57 of 100,000 in 2003 (an unexplained and substantial increase over the last 30 years, approximately 6% per year). No curative treatment except for radical surgery (almost never feasible) exists. The slow-growing TC exhibit a fairly good prognosis ( approximately 88%, 5-year survival), whereas AC demonstrate a 5-year survival of approximately 50%, and the highly malignant LCNEC and SCLC5-year survival of 15% to 57% and <5%, respectively. This review provides a broad overview on BP-NETs and focuses on the evolution of the disease, general features, and current diagnostic and therapeutic options.

Expression of L-type amino acid transporter 1 (LAT1) in neuroendocrine tumors of the lung

Amino acid transport systems play an important role in cellular proliferation. L-type amino acid transporter 1 (LAT1) has been associated with tumor growth, and is highly expressed in the established tumor cell lines and primary human neoplasms. In this study, we investigated the expression of LAT1 to evaluate the malignant potential and prognostic significance in neuroendocrine (NE) tumors of the lung. Twenty-one surgically resected, large cell neuroendocrine carcinomas (LCNEC), 13 small cell lung cancers (SCLC), five atypical carcinoids (AC), and 10 typical carcinoids (TC) were enrolled in the study. LAT1 expression and Ki-67 labeling index of the NE tumors were analyzed by immunohistochemical staining. LAT1 was overexpressed in 52.4% of the LCNEC, in 46.2% of the SCLC, and in 25% of the AC. LAT1 expression in LCNEC was significantly associated with lymph node metastasis and poor outcome. Moreover, a significant correlation was found between LAT1 expression and Ki-67 in both LCNEC and SCLC. Expression of LAT1 tended to increase from low-grade to high-grade NE tumors. The present results suggest that LAT1 may play a significant role in cellular proliferation, lymph node metastasis, and poor outcome in patients with NE tumors of the lung.

Neuroendocrine tumors of the diffuse neuroendocrine system

PURPOSE OF REVIEW

Neuroendocrine tumors (previously referred to as carcinoids) are ill-understood, enigmatic malignancies that, although slow-growing compared with adenocarcinomas, can behave aggressively. In 2004, they comprised 1.25% of all malignancies; their incidence is increasing by approximately 6% per year. The present review provides an overview on neuroendocrine tumors and focuses on general features and current diagnostic and therapeutic options.

RECENT FINDINGS

Neuroendocrine tumors may present a considerable diagnostic and therapeutic challenge as their clinical presentation is nonspecific and usually late, when metastases are already evident. Topographic localization is by computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, whole-body positron emission tomography or endoscopy/ultrasound. Bronchoscopy is useful to verify the diagnosis when lesions are located centrally in the bronchi. No curative treatment except for radical surgery (almost never feasible) exists. Palliative and symptomatic treatment is based on surgical debulking, tumor embolization, and biotherapy with somatostatin analogues. Chemotherapy and radiotherapy are usually ineffective, but novel drugs such as tyrosine kinase receptor inhibitors show promising results in phase II clinical studies.

SUMMARY

Tumors of the diffuse neuroendocrine system represent a significant and increasing clinical problem, and there is a need to develop both early diagnostic tests as well as to establish targeted therapeutic strategies.

Pediatric pulmonary tumors: primary and metastatic

Pediatric pulmonary tumors are rare. There is often a significant delay in diagnosis of pulmonary tumors secondary to their rarity and nonspecific presenting physiologic and radiographic findings. A high index of suspicion in pediatric patients with recurrent or persistent pulmonary symptoms is of paramount importance in diagnosing pulmonary tumors at an early stage. Malignant pulmonary tumors are more frequently diagnosed than benign lesions, with metastatic cancers being the most common. Complete surgical resection remains the basis of therapy for primary lesions, and its role in secondary cancers is becoming more established. Adjuvant therapies are frequently employed depending on the precise tumor involved. Mortality rates vary greatly depending on tumor location, stage, and type.