Correlation of chromogranin A levels and somatostatin receptor scintigraphy findings in the evaluation of metastases in carcinoid tumors. Ann Nucl Med. 2008;22:237-243. [PMID: 18535873 DOI: 10.1007/s12149-007-0123-y]

Gastroenteropancreatic neuroendocrine neoplasms: current development, challenges, and clinical perspectives

Neuroendocrine neoplasms (NENs) are highly heterogeneous and potentially malignant tumors arising from secretory cells of the neuroendocrine system. Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are the most common subtype of NENs. Historically, GEP-NENs have been regarded as infrequent and slow-growing malignancies; however, recent data have demonstrated that the worldwide prevalence and incidence of GEP-NENs have increased exponentially over the last three decades. In addition, an increasing number of studies have proven that GEP-NENs result in a limited life expectancy. These findings suggested that the natural biology of GEP-NENs is more aggressive than commonly assumed. Therefore, there is an urgent need for advanced researches focusing on the diagnosis and management of patients with GEP-NENs. In this review, we have summarized the limitations and recent advancements in our comprehension of the epidemiology, clinical presentations, pathology, molecular biology, diagnosis, and treatment of GEP-NETs to identify factors contributing to delays in diagnosis and timely treatment of these patients.

Primary Renal Well-Differentiated Neuroendocrine Tumors: Analyis of Six Cases from a Tertiary Care Center in North India with Review of Literature

Well-differentiated renal neuroendocrine tumors are rare tumors. As their biologic behavior is not fully known, there is a need to know more about these cases. We performed a retrospective chart review of all the cases diagnosed with renal neuroendocrine tumors from January 2016 to December 2020 (five years) in order to understand their clinical features, morphological characteristics and outcome. We included six cases with mean age of 46.2 years (4 males) in our study. All patients underwent radical nephrectomy. Histologically all showed tumor disposed in nests and trabeculae and majority of the tumors belonged to well-differentiated neuroendocrine tumor Grade 1 (WHO criteria of gastoroenteropancreatic neuroendocrine neoplasms). Lymph node metastasis was seen in two cases at the time of clinical presentation. All the tumors were diffusely positive for neuroendocrine tumor markers (synaptophysin, chromogranin, NSE, CD56). Follow-up data was available in all cases with an average follow-up of two years and neither has shown evidence of metastasis or relapse till last follow-up. Role of morphological patterns and immunohistochemical markers is highlighted with the importance of including Ki-67 index in grading them to better understand their outcome.

Chromogranin A: A Valuable Serum Diagnostic Marker for Non-Insulinoma Neuroendocrine Tumors of the Pancreas in a Chinese Population

Background

Pancreatic neuroendocrine tumors (P-NETs) are uncommon neoplasms, with few studies to date assessing serum biomarkers for the diagnosis of P-NETs. This study assessed the ability of serum chromogranin A (CgA) concentrations to distinguish P-NETs from other pancreatic lesions in a Chinese population and to determine the histological grades of P-NETs.

Material/Methods

This prospective study enrolled 165 patients, including 73 with proven P-NETs, 60 with malignant tumors of the pancreas, and 32 with benign lesions of the pancreas. Serum CgA concentrations were measured by ELISA.

Results

Serum CgA concentrations were significantly higher in patients with P-NET than in patients with other pancreatic malignancies and benign lesions (P<0.001), but did not differ significantly in the latter 2 groups (P=0.827). Serum CgA concentrations were significantly higher in patients with non-insulinoma P-NETs than in the other groups (P<0.001), but did not differ significantly in patients with insulinoma and patients with non-P-NETs (P=0.668). Receiver operating characteristic (ROC) curves revealed that a serum CgA concentration of 77.8 ng/ml could distinguish patients with non-insulinoma P-NETs from patients with non-P-NETs, with a sensitivity of 96.7%, a specificity of 76.1%, and an area under the ROC curve of 0.897. In patients with P-NETs, multifactor analysis showed that the non-insulinoma subtype and the presence of liver metastases were associated with elevated serum CgA (both p<0.001).

Conclusions

Serum CgA concentration may be a valuable diagnostic biomarker for non-insulinoma P-NETs. Elevated serum CgA is likely associated with liver metastases.

Somatostatin receptor scintigraphy in the follow up of neuroendocrine neoplasms of appendix

BACKGROUND

Neuroendocrine tumors of appendix (ANETs) known as carcinoids, are rare endocrine neoplasms originated from enterochromaffin cells of gastrointestinal tract. ANETs are the third most frequent (16.7%) gastrointestinal neuroendocrine tumors, with the incidence of 0.08-0.2 cases/100000 during one year. Incidental ANETs occur in 0.2%-0.7% of emergency surgical resections because of suspected appendicitis which is usually the first manifestation of ANET. Although there are a lot of papers about application of somatostatin receptor scintigraphy in gastrointestinal neuroendocrine tumors, there are very rare sporadic cases described about ANETs particularly.

AIM

To establish the role of somatostatin receptor scintigraphy (SRS) in the management of patients with neuroendocrine tumors of appendix (ANET).

METHODS

The total of 35 patients was investigated, 23 females and 12 males, average age (43.7 ± 17.3 years). All patients had histological diagnosis of ANET (34 carcinoids of appendix and one tubular carcinoid). Majority of tumors have been found incidentally during surgery of: Acute appendicitis (n = 15), perforated appendicitis (n = 2), ileus (n = 3), hysterectomy (n = 3), ruptured ovarian cyst (n = 2), caecal volvulus (n = 1), while 9 patients had diagnosis of appendiceal tumor before the surgery. Seventeen patients had tumor grade (G) G1, 12 G2 and 6 G3. The right hemicolectomy was performed in 13, while the rest of the patients had appendectomy only. SRS was done early (2 h) and late (24 h) after i.v. application of 740 MBq technetium-99m ethylenediamine-N, N'-diacetic acid Hydrazinonicotinyl-Tyr3-Octreotide (technetium-99m-Tektrotyd, Polatom, Poland). SRS was performed for restaging in all the patients after surgery.

RESULTS

There were 12 true positive (TP), 19 true negative, 3 false positive and 1 false negative SRS result. Sensitivity of the method was 92.31%, specificity was 86.36%, positive predictive value was 80.00%, negative predictive value was 95.00% and accuracy 88.57%. Receiver operating characteristics analysis showed that SRS scintigraphy is a good test for detection TP cases [area under the curve of 0.850, 95% confidence interval (CI): 0.710-0.990, P < 001]. Single photon emission computed tomography contributed diagnosis in 7 TP findings. In 10 patients Krenning score was 4 and in 2 was 3. In 8 patients SRS significantly changed the management of the patients (in two surgery was repeated, in 4 somatostatin analogues and in two peptide receptor radionuclide therapy). Median progression-free survival in SRS positive patients was 52 months (95%CI: 39.7-117.3 mo) while in SRS negative patients it was 60 months (95%CI: 42.8-77.1 mo), without statistically significant difference between the two groups (P = 0.434).

CONCLUSION

In conclusion, our results confirmed the value of SRS in the follow-up of the patients with ANET after surgery, if recurrences or metastases are suspected.

Neuroendocrine neoplasms: current and potential diagnostic, predictive and prognostic markers

Some biomarkers for functioning and non-functioning neuroendocrine neoplasms (NENs) are currently available. Despite their application in clinical practice, results should be interpreted cautiously. Considering the variable sensitivity and specificity of these parameters, there is an unmet need for novel biomarkers to improve diagnosis and predict patient outcome. Nowadays, several new biomarkers are being evaluated and may become future tools for the management of NENs. These biomarkers include (1) peptides and growth factors; (2) DNA and RNA markers based on genomics analysis, for example, the so-called NET test, which has been developed for analyzing gene transcripts in circulating blood; (3) circulating tumor/endothelial/progenitor cells or cell-free tumor DNA, which represent minimally invasive methods that would provide additional information for monitoring treatment response and (4) improved imaging techniques with novel radiolabeled somatostatin analogs or peptides. Below we summarize some future directions in the development of novel diagnostic and predictive/prognostic biomarkers in NENs. This review is focused on circulating and selected tissue markers.

Role of biomarker tests for diagnosis of neuroendocrine tumours

Neuroendocrine tumours (NETs) are neoplasms that arise from neuroendocrine cells. Neuroendocrine cells and their tumours can secrete a wide range of amines and polypeptide hormones into the systemic circulation. This feature has triggered widespread investigation into circulating biomarkers for the diagnosis of NETs as well as for the prediction of the biological behaviour of tumour cells. Classic examples of circulating biomarkers for gastroenteropancreatic NETs include chromogranin A, neuron-specific enolase and pancreatic polypeptide as well as hormones that elicit clinical syndromes, such as serotonin and its metabolites, insulin, glucagon and gastrin. Biomarker metrics of general markers for diagnosing all gastroenteropancreatic NET subtypes are limited, but specific hormonal measurements can be of diagnostic value in select cases. In the past decade, methods for detecting circulating transcripts and tumour cells have been developed to improve the diagnosis of patients with NETs. Concurrently, modern scanning techniques and superior radiotracers for functional imaging have markedly expanded the options for clinicians dealing with NETs. Here, we review the latest research on biomarkers in the NET field to provide clinicians with a comprehensive overview of relevant diagnostic biomarkers that can be implemented in dedicated situations.

Baseline chromogranin A and its dynamics are prognostic markers in gastroenteropancreatic neuroendocrine tumors

Aim: This study assessed whether absolute chromogranin A (CgA) values at various stages of treatment have prognostic value in patients with pancreatic and midgut neuroendocrine tumors, subjected to peptide receptor radionuclide therapy with 90Y-[DOTA0, D-Phe1, Tyr3]-octreotate. Patients & methods: CgA was determined before peptide receptor radionuclide therapy, 6 weeks, 6, 12, 18 and 24 months after the last dose of 90Y-[DOTA0, D-Phe1, Tyr3]-octreotate. The primary end point was overall survival. Results: Elevated baseline CgA concentrations and their relative increase within the first year of observation were unfavorable predictors of overall survival, but not progression. Conclusion: Even a single baseline measurement of CgA can be useful in establishing prognosis in this group, if this parameter exceeds its upper normal limit more than tenfold.

Clinical Translation of a Click-Labeled 18F-Octreotate Radioligand for Imaging Neuroendocrine Tumors

We conducted the first-in-human study of (18)F-fluoroethyl triazole [Tyr(3)] octreotate ((18)F-FET-βAG-TOCA) in patients with neuroendocrine tumors (NETs) to evaluate biodistribution, dosimetry, and safety. Despite advances in clinical imaging, detection and quantification of NET activity remains a challenge, with no universally accepted imaging standard.

METHODS

Nine patients were enrolled. Eight patients had sporadic NETs, and 1 had multiple endocrine neoplasia type 1 syndrome. Patients received 137-163 MBq (mean ± SD, 155.7 ± 8 MBq) of (18)F-FET-βAG-TOCA. Safety data were obtained during and 24 h after radioligand administration. Patients underwent detailed whole-body PET/CT multibed scanning over 4 h with sampling of venous bloods for radioactivity and radioactive metabolite quantification. Regions of interest were defined to derive individual and mean organ residence times; effective dose was calculated with OLINDA 1.1.

RESULTS

All patients tolerated (18)F-FET-βAG-TOCA with no adverse events. Over 60% parent radioligand was present in plasma at 60 min. High tumor (primary and metastases)-to-background contrast images were observed. Physiologic distribution was seen in the pituitary, salivary glands, thyroid, and spleen, with low background distribution in the liver, an organ in which metastases commonly occur. The organs receiving highest absorbed dose were the gallbladder, spleen, stomach, liver, kidneys, and bladder. The calculated effective dose over all subjects (mean ± SD) was 0.029 ± 0.004 mSv/MBq.

CONCLUSION

The favorable safety, imaging, and dosimetric profile makes (18)F-FET-βAG-TOCA a promising candidate radioligand for staging and management of NETs. Clinical studies in an expanded cohort are ongoing to clinically qualify this agent.

Primary renal carcinoid tumour with lung metastasis misdiagnosed as renal cell carcinoma

A 58-year-old man with a history of metastatic renal cell carcinoma (RCC) diagnosed 10 years prior, status post right nephrectomy, presented for evaluation of pulmonary nodules. A year after the nephrectomy, he had undergone cutaneous metastasectomy in the right flank area, and a further 2 years later he had had his second cutaneous metastasectomy in the right chest wall. Both cutaneous pathologies had, at the time, shown metastatic neoplasm with histological features compatible with those of the previous renal tumour. He was treated with sorafenib. 3 years later he developed asymptomatic pulmonary nodules, which gradually doubled in size over the next 2.5 years. He underwent bronchoscopy and left lower lobe biopsy. Pathology revealed a metastatic renal carcinoid/neuroendocrine tumour. Second review of the previous renal neoplasm and the cutaneous metastatic pathology showed trabecular architecture, consistent with carcinoid, but mimicking the long parallel arrays that have been described in some cases of papillary RCC.

Chromogranin A - unspecific neuroendocrine marker. Clinical utility and potential diagnostic pitfalls

Chromogranin A, despite a number of limitations, is still the most valuable marker of neuroendocrine tumors (NETs). Granins belong to the family of acidic proteins that constitute a major component of secretory granules of various endocrine and neuroendocrine cells, which are components of both the classical endocrine glands and the diffuse neuroendocrine system. These cells are a potential source of transformation into neuroendocrine tumors. The awareness of potential causes influencing the false results of its concentrations simplifies diagnosis and treatment. One of the disadvantages of this marker is its non-specificity and the existence of a number of pathological processes leading to an increase in its concentration, which often results in confusion and diagnostic difficulties. The molecular structure is characterized by a number of sites susceptible to the proteolytic activity of enzymes, resulting in the formation of a number of biologically active peptides. Presumably they act as precursors of active proteins. Chromogranin expression correlates with the amount of secretory vesicles in neuroendocrine cells. The peptide chain during biochemical changes becomes a precursor of biologically active proteins with a wide range of activities. There are a number of commercially available kits for the determination of chromogranin A, which differ in methodology. We present the evaluation of chromogranin A as a marker of neuroendocrine tumors in clinical practice and the possible factors that may affect the outcome of its concentration.

The Role of Plasma Chromogranin A as Assessment of Treatment Response in Non-functioning Gastroenteropancreatic Neuroendocrine Tumors

PURPOSE

Chromogranin A (CgA) has been considered to be valuable not only in the diagnosis but also in monitoring the disease response to treatment. However, only a few studies have been published on this issue. We purposed to evaluate whether biochemical response using plasma CgA level is reliable in concordance with the clinical response of grade 1-3 nonfunctiong gastroenteropancreatic neuroendocrine tumors (GEP-NETs).

MATERIALS AND METHODS

Between March 2011 and September 2013, a total of 27 cases in 18 patients were analysed, clinically and radiologically while serial CgA tests were also conducted during treatment. Tumor responses were defined by both Response Evaluation Criteria in Solid Tumors (RECIST) criteria ver. 1.1 and biochemical criteria based on the CgA level.

RESULTS

Among the 27 cases analysed, no difference in the basal CgA level was observed with regard to gender, primary tumor site, tumor grade (World Health Organization classification), liver metastasis, number of metastatic site, and line of chemotherapy. The overall response rate (RR) by RECIST criteria ver. 1.1 was six out of the 27 cases (22.2%) and eight out of the 27 cases (29.6%) for biochemical RR. The overall concordance rates of the response based on RECIST and biochemical criteria were 74%. In grades 1 and 2 GEP-NETs (n=17), the concordance rate of the disease control was 94.1%. There was a significant difference for progression-free survival (PFS) between responders and non-responder in accordance to biochemical criteria (35.73 months vs. 5.93 months, p=0.05).

CONCLUSION

This study revealed that changes of the plasma CgA levels were associated with tumour response. Additionally, biochemical response based on serial CgA may be a predictive marker for PFS in GEP-NETs.

Primary carcinoid tumour of the kidney: a review of the literature

Context. Primary renal carcinoid tumours are rare. Their pathogenesis is unknown and the clinical presentation is similar to other renal tumours thus posing diagnostic dilemmas for clinicians. Objectives. To review the literature for case reports of primary renal carcinoids. Methods. Literature was extensively searched for case reports for primary renal carcinoids. Reports of metastatic carcinoids to the kidneys were excluded. Results. Approximately less than 90 cases of primary carcinoid tumours of the kidney have been reported in the literature. A total of 29 cases of primary renal carcinoids were reviewed. The mean age of presentation was 48 years (range 29–75) with both right kidney (48.3%) and left kidney (44.8%) being equally affected. 28.6% of the cases reviewed were diagnosed as an incidental finding. The mean followup time was 20 months with 73.1% of patients without evidence of disease after surgical treatment (radical or partial nephrectomy). Primary carcinoid tumours of the kidney are often well differentiated tumours. They are often misdiagnosed because of their rarity and similar presentation with other renal tumours. Conclusions. Primary carcinoid tumours of the kidney are rare tumours with an indolent course with frequent metastasis. Metastatic work up and followup is required in their management.

The identification of gut neuroendocrine tumor disease by multiple synchronous transcript analysis in blood

Gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs) are increasing in both incidence and prevalence. A delay in correct diagnosis is common for these lesions. This reflects the absence of specific blood biomarkers to detect NENs. Measurement of the neuroendocrine secretory peptide Chromogranin A (CgA) is used, but is a single value, is non-specific and assay data are highly variable. To facilitate tumor detection, we developed a multi-transcript molecular signature for PCR-based blood analysis. NEN transcripts were identified by computational analysis of 3 microarray datasets: NEN tissue (n = 15), NEN peripheral blood (n = 7), and adenocarcinoma (n = 363 tumors). The candidate gene signature was examined in 130 blood samples (NENs: n = 63) and validated in two independent sets (Set 1 [n = 115, NENs: n = 72]; Set 2 [n = 120, NENs: n = 58]). Comparison with CgA (ELISA) was undertaken in 176 samples (NENs: n = 81). 51 significantly elevated transcript markers were identified. Gene-based classifiers detected NENs in independent sets with high sensitivity (85–98%), specificity (93–97%), PPV (95–96%) and NPV (87–98%). The AUC for the NEN gene-based classifiers was 0.95–0.98 compared to 0.64 for CgA (Z-statistic 6.97–11.42, p<0.0001). Overall, the gene-based classifier was significantly (χ² = 12.3, p<0.0005) more accurate than CgA. In a sub-analysis, pancreatic NENs and gastrointestinal NENs could be identified with similar efficacy (79–88% sensitivity, 94% specificity), as could metastases (85%). In patients with low CgA, 91% exhibited elevated transcript markers. A panel of 51 marker genes differentiates NENs from controls with a high PPV and NPV (>90%), identifies pancreatic and gastrointestinal NENs with similar efficacy, and confirms GEP-NENs when CgA levels are low. The panel is significantly more accurate than the CgA assay. This reflects its utility to identify multiple diverse biological components of NENs. Application of this sensitive and specific PCR-based blood test to NENs will allow accurate detection of disease, and potentially define disease progress enabling monitoring of treatment efficacy.

Frequency and characterization of gastro-entero-pancreatic neuroendocrine tumor patients with high-grade of uptake at somatostatin receptor scintigraphy

Recent studies suggest that the somatostatin receptor scintigraphy (SRS) grade of uptake is a predictor of response to peptide receptor radionuclide therapy (PRRT). To identify and characterize patients with well-differentiated (WD) neuroendocrine neoplasm (NEN) displaying a high-grade uptake at SRS. Patients with WD-NEN, whose SRS films were available for review, were retrospectively included. SRS was reviewed by three independent readers and classified into four subgroups based on a modified Krenning's scale (mKS): no uptake (group-0), homogeneous grade 1-2 uptake (group-1), homogeneous grade 3-4 (group-2), and heterogeneous grade 1-4 (group-3). A simplified scale (sS) of SRS was also used to look for characteristics of patients with high-grade uptake. One hundred and six WD-NEN patients were enrolled. Group-0, group-1, group-2, and group-3 were found in 17, 8, 33, and 42% of cases respectively. High-grade uptake at sS (75% of cases) was correlated with older age, functioning NEN, high chromogranin-A level, and grade 1 (G1) NEN based on mitotic count. Based on the mKS or sS scales, no difference on survival was found. Thirty-three to seventy-five percent of metastatic NEN patients can be considered candidates for PRRT based on homogeneous or heterogeneous high-grade uptake. Functioning G1 NEN patients could be the best candidates for PRRT. Randomized trials are expected to confirm this result.

[Chromogranin A and neuroendocrine tumors]

Chromogranin A (CgA) is the most abundant granin in gastroenteropancreatic neuroendocrine tumors (GEP-NETs). As a tumor marker is moderately sensitive and nonspecific. Despite the limitations of testing methods, which require careful interpretation, especially in the case of gastrinomas, patients treated with somatostatin analogues, and poorly differentiated tumors, it is the best tumor marker in GEP-NETs and may be of value in other tumors with neuroendocrine differentiation. CgA may be used as a marker in blood or tissue samples through immunohistochemical techniques. CgA levels correlate with tumor burden and extension and may be used for diagnosis and monitoring of GEP-NETs, especially midgut carcinoids and endocrine pancreatic tumors. It is also useful as a prognostic marker for detection of recurrence and monitoring of response to different treatments.

Chromogranin A: a sensitive biomarker for the detection and post-treatment monitoring of gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are a heterogeneous group of neoplasms that arise from neuroendocrine cells of the GI tract and pancreas. Due to the lack of symptoms in the early stage of the disease and the frequency of nonspecific gastrointestinal symptoms, GEP-NET are difficult to diagnose. This delay in diagnosis often results in patients presenting with advanced disease and thus a poor prognosis. There is an unmet medical need for earlier, more definitive GEP-NET diagnosis. Identification of effective biomarkers to improve GEP-NET diagnosis, as well as to assess treatment efficacy, relapse and prognosis, is important for improving outcomes in GEP-NET. Chromogranin A is currently the most useful general biomarker for the assessment of GEP-NET. This review summarizes the biochemical characteristics of chromogranin A, its specificity and sensitivity for GEP-NET diagnosis, and its use in monitoring treatment effectiveness, disease progression and prognosis.

Chromogranin A is a reliable biomarker for gastroenteropancreatic neuroendocrine tumors in an Asian population of patients

PURPOSE

To evaluate the significance of plasma chromogranin A (CgA) levels in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NET) in terms of disease status and treatment responses.

MATERIALS AND METHODS

Forty-four GEP-NET patients comprising 15 disease-free patients and 29 patients with active disease, as well as 26 healthy participants were enrolled in this study between April 2010 and April 2011. Clinicopathological factors were collected and serial plasma CgA levels were measured.

RESULTS

Plasma CgA levels were significantly higher in GEP-NET patients with active disease than in disease-free patients (p = 0.011) or healthy participants (p = 0.001). No difference in CgA levels was observed in terms of primary tumor location, tumor grade, and functional status in patients with active disease. CgA values at 94 U/l distinguished healthy individuals or disease-free patients from patients with active disease. Sensitivity and specificity rates were 86 and 88%, respectively. CgA levels at 110 U/l differentiated patients without recurrence from those with recurrence, with a sensitivity rate of 100% and a specificity rate of 80%. Patients (5/5, 100%) with stable disease and who showed partial response after treatment had a more than 20% decrease in CgA levels compared with the baseline values. Patients (6/6, 100%) with progressive disease showed a less than 20% decrease or increase in CgA levels.

CONCLUSION

The plasma CgA level is a reliable biomarker for GEP-NET. We conclude that changes in CgA levels are associated with disease status and treatment responses.

[Current diagnostic procedure on neuroendocrine differentiation of prostate cancer]

Chromogranin A (CgA) is considered as a major specific neuroendocrine tumor marker. It belongs to the secretogranin family, which is present in the gastrointestinal tract, respiratory system, endocrine glands and in a group of endocrine cells such us pancreas and thyroid. Serum levels of CgA could reflect the neuroendocrine activity and could be used when evaluating advance prostate carcinoma. Moreover, there are also several factors that may increase the serum level of CgA: treatment with proton-pump inhibitors or H2-receptor blockers, chronic atrophic gastritis, rheumatoid arthritis, liver and renal failure. Another method to evaluate NE differentiation is scintigraphy with the 111In-labeled somatostatin analogue (DTPA-D-Phe)-octrotide, (Octreoscan). This method takes advantage of the overexpression of type II somatostatin receptors on the cell surface of NE tumors. With this technique the presence of NE differentiation can be detected both at the primary (prostate) and the metastatic sites. A more specific system to detect NE cell activity is obtained by analyzing CgA gene expression in prostate tissue by a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR).

The clinical relevance of chromogranin A as a biomarker for gastroenteropancreatic neuroendocrine tumors

Chromogranin A, although it exhibits limitations, is currently the most useful general tumor biomarker available for use in the diagnosis and management of gastroenteropancreatic neuroendocrine tumors (NETs). The value of the chromogranin A lies in its universal cosecretion by the majority of neuroendocrine cells that persists after malignant transformation. Clinicians aware of the physiologic role of chromogranin A and its secretion in a variety of non-NET-related pathologic conditions can use this protein as a moderately effective tumor biomarker in the management of GEP-NETs.

Plasma chromogranin A response to octreotide test: prognostic value for clinical outcome in endocrine digestive tumors

OBJECTIVES

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) expressing somatostatin receptors may be treated with somatostatin analogs (SSAs). Selection criteria are a positive Octreoscan or a >50% hormone level decrease after octreotide subcutaneous (s.c.) injection (octreotide test) (OT). Plasma chromogranin A (CgA) is the best general GEP-NET marker, but data on CgA response to OT are scanty. Thus, we evaluated whether plasma CgA response to OT could predict the clinical response to SSAs.

METHODS

At diagnosis, 38 GEP-NET patients received octreotide 200 microg s.c., with plasma CgA determination at 0, 3, and 6 h. Long-term SSA treatment was then given by monitoring symptomatic, biochemical, and objective responses, and survival.

RESULTS

Basal plasma CgA levels were significantly higher in patients with functioning than non-functioning tumors (median (range): 220 (18-2,230) vs. 46 (25-8,610) U/l, P=0.03) and in those with than without metastases (171 (18-8,610) vs. 43 (28-220) U/l, P=0.04). CgA levels significantly correlated with WHO classification, clinical TNM staging, and Ki-67 proliferative index. After OT, CgA levels decreased from 146 (18-8,610) to 61 (10-8,535) U/l (basal and nadir values), P<0.001. In patients responsive to OT, a successful objective response occurred in 21/31 patients (68%). Successful symptomatic response occurred in 13/18 patients (72%), biochemical response in 25/31 (81%), and objective response in 21/31 (68%). In the remaining seven unresponsive cases, with CgA decrement <30%, disease progressed to death in six (86%). Median survival from enrollment was 48 months (6-138) in responsive and 6 (6-30) in unresponsive patients (P=0.0005).

CONCLUSIONS

In GEP-NETs, plasma CgA is a reliable marker, and a >30% decrease after OT has a relevant prognostic meaning allowing the identification of the subgroup of patients most likely to be responsive to chronic SSAs.

Chromogranin A--biological function and clinical utility in neuro endocrine tumor disease

BACKGROUND

Neuroendocrine tumors (NETs) are a form of cancer that differ from other neoplasia in that they synthesize, store, and secrete peptides, e.g., chromogranin A (CgA) and amines. A critical issue is late diagnosis due to failure to identify symptoms or to establish the biochemical diagnosis. We review here the utility of CgA measurement in NETs and describe its biological role and the clinical value of its measurement.

METHODS

Literature review and analysis of the utility of plasma/serum CgA measurements in NETs and other diseases.

RESULTS

CgA is a member of the chromogranin family; its transcription and peptide processing are well characterized, but its precise function remains unknown. Levels are detectable in the circulation but vary substantially (approximately 25%) depending on which assay is used. Serum and plasma measurements are concordant. CgA is elevated in approximately 90% of gut NETs and correlates with tumor burden and recurrence. Highest values are noted in ileal NETs and gastrointestinal NETs associated with multiple endocrine neoplasia type 1. Both functioning and nonfunctioning pancreatic NETs have elevated values. CgA is more frequently elevated in well-differentiated tumors compared to poorly differentiated NETs. Effective treatment is often associated with decrease in CgA levels. Proton pump inhibitors falsely increase CgA, but levels normalize with therapy cessation.

CONCLUSIONS

CgA is currently the best available biomarker for the diagnosis of NETs. It is critical to establish diagnosis and has some utility in predicting disease recurrence, outcome, and efficacy of therapy. Measurement of plasma CgA is mandatory for the effective diagnosis and management of NET disease.

Visualization of somatostatin receptors in prostate cancer and its bone metastases with Ga-68-DOTATOC PET/CT

PURPOSE

To assess DOTATOC-affine somatostatin receptor expression in advanced prostate cancer and its bone metastases with regard to DOTATOC-mediated receptor therapies, using a Ga-68-DOTATOC PET/CT.

PROCEDURES

Twenty consecutive patients with advanced prostate cancer underwent bone scintigraphy, followed by Ga-68-DOTATOC PET/CT within 3 weeks. Through side-by-side comparison with bone scintigraphy, the number of visible bone metastases on PET was determined. In addition, in cases of visible metastases, the maximum standard uptake value (SUV(max)) of Ga-68-DOTATOC was measured in the metastases and in normal bone. In patients who did not undergo a prostatectomy (n = 12), the SUV(max) was additionally measured in the prostate and in adjacent tissue. For focal lesions, the difference in SUV(max) (Delta SUV(max)) between the metastases and normal bone was calculated. For patients still having their prostate, a Delta SUV(max) between the prostate and its adjacent tissue was calculated.

RESULTS

Sixty four of 216 metastases (30%) were visible in 13 patients with focal metastases. Of six patients with diffuse metastases (superscan), one showed diffuse metastases, three showed a total of ten focal metastases, and two showed no correlate on PET. One patient with a neuroendocrine prostate cancer showed no correlate on PET. The maximum Delta SUV(max) between metastases and normal bone was 4.9 (mean = 1.6 +/- 0.9) and between the prostate and adjacent tissue 5.9 (mean = 2.8 +/- 1.6).

CONCLUSIONS

In prostate cancer and its bone metastases, DOTATOC-affine somatostatin receptors (subtype 2 and 5) can be visualized with Ga-68-DOTATOC PET/CT. But their expression is so weak that other conjugates should be tested for receptor-mediated therapies which are better at addressing the prostate cancer-specific somatostatin receptor subtypes 1 and 4-or even other receptors.