Therapy-related myeloid neoplasm after peptide receptor radionuclide therapy (PRRT) in 1631 patients from our 20 years of experiences: prognostic parameters and overall survival

PURPOSE

To determine prognostic factors and overall survival (OS) in therapy-related myeloid neoplasm (t-MN) of patients after receiving peptide receptor radionuclide therapy (PRRT).

METHODS

All patients treated from February 1999 until September 2019 at our center who had bone marrow biopsy-proven t-MN after PRRT were included. Patient characteristics, laboratory results, and all tumor-directed therapies before t-MN diagnosis were collected. Cox regression analysis was performed to identify parameters associated with OS. Receiver operating characteristic (ROC) curve analysis was used to define cutoff values as well as sensitivity and specificity of the parameters.

RESULTS

Out of 1631 patients treated with PRRT, 30 patients developed t-MN comprising myelodysplastic syndrome (MDS) in 23 patients (77%) and acute myeloid leukemia (AML) in 7 patients (23%). The median OS of t-MN patients was 13 months (range 9.1-16.9 months): 6 months for AML and 15 months for the MDS subgroup, respectively. Higher platelet level was a significant prognostic parameter for longer OS (hazard ratio (HR): 0.99, P < 0.05). Using ROC analysis, the best cutoff value for thrombocyte count was 183.5 Gpt/L, resulting in a sensitivity of 92.3% and a specificity of 50%. Other factors, such as hemoglobin level, did not show a significant correlation with OS.

CONCLUSION

Even rarely occurred, the OS is gravely compromised in t-MN patients after PRRT, and even less in the AML subgroup (6 months). Higher platelet value was a significant prognostic parameter for longer OS in t-MN patients.

177Lu-PSMA radioligand therapy of predominant lymph node metastatic prostate cancer

¹⁷⁷Lu-PSMA radioligand therapy (LuPRLT) is mainly used for patients with metastatic castration-resistant prostate cancer who are resistant to established drugs. This study describes LuPRLT, either LuPSMA I&T or LuPSMA RLT-617, for 45 patients with predominant lymph node metastatic prostate cancer (LNM PC). Thirty-five patients had LNM and ten patients had LNM and one or two bone metastases. Before LuPRLT, the patients had prostate specific antigen (PSA) of median 18 µg/l (interquartile range (IQR): 3.3–39). LuPRLT was given with a cumulative injected ¹⁷⁷Lu activity of median 14.5 GBq (IQR: 12.2–20.4). Maximum percentage decline of PSA was median 92% (IQR: 70–99). Thirty-five patients with only LNM had a better overall survival (OS) than ten patients with LNM and one or two bone metastases. Thirty-three docetaxel-naïve patients had a longer PSMA PET/CT progression-free survival than twelve patients who were resistant to docetaxel. Twenty-two patients who received LuPRLT with a cumulative injected ¹⁷⁷Lu activity ≥ 14.8 GBq had a better PSMA PET/CT progression-free survival than 23 patients who received LuPRLT with a lower cumulative injected ¹⁷⁷Lu activity. Seventeen patients with relapse after LuPRLT who received rechallenge LuPRLT or ActPRLT had a better OS than five patients who received other forms for relapse treatment. LuPRLT gave mild and transitory adverse effects. The findings of the present study suggest that LuPRLT of patients with LNM may be effective and safe. The promising results motivate randomized phase II trials to further quantify the impact of LuPRLT as treatment of patients with LNM.

How to Overcome the Disturbing Effects of Human Anti-Mouse Antibodies (Hama) on in Vitro Assays

The development of human anti-mouse antibodies (HAMA) is a common immune response in patients with ovarian carcinoma after repeated injections of murine anti-CA 125 monoclonal antibodies for immunoscintigraphy. As a tumor marker with significant diagnostic value CA 125 is routinely measured in the follow-up of tumor patients by immunoradiometric assays (IRMA) based on murine anti-CA 125 monoclonal antibodies. HAMA may cause false-positive findings in a CA 125-IRMA. In this report our group demonstrates a simple way of eliminating HAMA by protein A/G affinity chromatography allowing the reliable detection of the tumor marker CA 125 in the serum of patients with ovarian carcinoma.

Radioimmunoscintigraphy Using Monoclonal Antibodies to CEA, CA 19-9 and CA 125

131I labelled F (ab’)2 fragments of monoclonal antibodies against CA 19-9 and CEA (“radioimmunococktail” IMACIS 1) were used in a prospective study (n = 60 patients) and in a retrospective study (n = 32 patients) for the detection of colorectal carcinomas (n = 67) and other gastrointestinal CEA/CA 19-9-producing tumors (n = 32). Sensitivity was 82% and specificity 90%. Immunoscintigraphy proved useful and complementary to CT scan and sonography, especially in the diagnosis of pelvic recurrences and intra-abdominal metastases.

In addition, monoclonal antibody OC 125 (IMACIS 2) was used for the detection of ovarian carcinomas (n = 10) and other CA 125 producing tumors. Immunoscintigraphy was positive in all patients (n = 18) suggesting that this radioimmunological approach could be of use in the staging, therapeutic control and earlier diagnosis of recurrent epithelial ovarian carcinoma.

A Preliminary Study on the Functional Analysis of Peripheral Blood Lymphocytes from Ovarian Cancer Patients Developing Hama after Immunoscintigraphy

In the follow-up of ovarian cancer patients, rising levels of the tumor-associated antigen CA 125 are an indication for immunoscintigraphy. Human anti-mouse antibodies (HAMA) are frequently found after immunoscintigraphy with murine MAb directed against CA 125. Since we observed that patients developing high HAMA-levels in serum remained free of tumor or had stable disease, we examined the cytotoxic activity of peripheral blood lymphocytes (PBL) by a fluorescence-based assay. Our results demonstrate that PBLs of patients with high anti-idiotypic antibodies show an increased cytotoxic activity (by a factor of 4) compared to those of patients with low HAMA levels. The clinical course of the patients after the first injection of murine monoclonal antibody was observed over a period of 1 to 3 years. Improvement or deterioration of patients ‘ clinical condition corresponded with the results obtained by functional analysis. Further investigations concerning the course of cytotoxic activity in HAMA-positive patients will have to clarify HAMA's role in the immune response.

Tumor Markers, Liver Function Tests and Symptoms in 115 Patients with Isolated Colorectal Liver Metastases

Development of the hybridoma technique has made the identification of several new tumor antigens possible. Although it was hoped that they would be more tumor-specific, none of these markers are found exclusively in tumor or in serum of tumor patients. Compared with carcinoembryionic antigen (CEA) and liver function tests, the roles of these markers (CA 19-9, CA 125, CA 15-3) were prospectively evaluated in 115 patients with colorectal liver metastases. Patients were classified according to tumor volume (T1 <25%, T2 25-75%, T3 >75%), and the extension of infiltration (solitary/multiple/diffuse; unilateral, bilateral). Patients with benign liver or biliary disease served as a control group (n=63). Overall sensitivity was 87% for *1 , 50% for *2 and 38% for *3 , with a significant correlation with tumor size. CEA serum levels were elevated in 88% of all patients. CA 19-9 was less sensitive: positive in 59%. Because of some complementary elevations, the combined use of CEA, CA 19-9 and CA 125 raised sensitivity to 94%. CA 19-9 and LDH could be useful for confirmation because of their higher specificity; however, the specificity of CEA rose to 93% on using a cut-off of 10 ng/ml instead of 3 ng/ml. The results indicate that CEA and CA 19-9 as well as liver function tests are helpful for preoperative staging in conjunction with imaging procedures before liver resection or regional chemotherapy.

32nd International Austrian Winter Symposium : Zell am See, the Netherlands. 20-23 January 2016

A1 68Ga-PSMA PET/CT in staging and restaging of Prostate Cancer Patients: comparative study with 18F-Choline PET/CT

W Langsteger, A Rezaee, W Loidl, HS Geinitz, F Fitz, M Steinmair, G Broinger, L Pallwien-Prettner, M Beheshti

A2 F18 Choline PET – CT: an accurate diagnostic tool for the detection of parathyroid adenoma?

L Imamovic, M Beheshti, G Rendl, D Hackl, O Tsybrovsky, M Steinmair, K Emmanuel, F Moinfar, C Pirich, W Langsteger

A3 [18F]Fluoro-DOPA-PET/CT in the primary diagnosis of medullary thyroid carcinoma

A Bytyqi, G Karanikas, M Mayerhöfer, O Koperek, B Niederle, M Hartenbach

A4 Variations of clinical PET/MR operations: An international survey on the clinical utilization of PET/MRI

T Beyer, K Herrmann, J Czernin

A5 Standard Dixon-based attenuation correction in combined PET/MRI: Reproducibility and the possibility of Lean body mass estimation

I Rausch, P Rust, MD DiFranco, M Lassen, A Stadlbauer, ME Mayerhöfer, M Hartenbach, M Hacker, T Beyer

A6 High resolution digital FDG PET/MRI imaging for assessment of ACL graft viability

K Binzel, R Magnussen, W Wei, MU Knopp, DC Flanigan, C Kaeding, MV Knopp

A7 Using pre-existing hematotoxicity as predictor for severe side effects and number of treatment cycles of Xofigo therapy

A Leisser, M Nejabat, M Hartenbach, G Kramer, M Krainer, M Hacker, A Haug

A8 QDOSE – comprehensive software solution for internal dose assessment

Wencke Lehnert, Karl Schmidt, Sharok Kimiaei, Marcus Bronzel, Andreas Kluge

A9 Clinical impact of Time-of-Flight on next-generation digital PET imaging of Yttrium-90 radioactivity following liver radioembolization

CL Wright, K Binzel, J Zhang, Evan Wuthrick, Piotr Maniawski, MV Knopp

A10 Snakes in patients! Lessons learned from programming active contours for automated organ segmentation

M Blaickner, E Rados, A Huber, M Dulovits, H Kulkarni, S Wiessalla, C Schuchardt, RP Baum, B Knäusl, D Georg

A11 Influence of a genetic polymorphism on brain uptake of the dual ABCB1/ABCG2 substrate [11C]tariquidar

M Bauer, B Wulkersdorfer, W Wadsak, C Philippe, H Haslacher, M Zeitlinger, O Langer

A12 Outcome prediction of temporal lobe epilepsy surgery from P-glycoprotein activity. Pooled analysis of (R)-[11C]-verapamil PET data from two European centres

M Bauer, M Feldmann, R Karch, W Wadsak, M Zeitlinger, MJ Koepp, M-C Asselin, E Pataraia, O Langer

A13 In-vitro and in-vivo characterization of [18F]FE@SNAP and derivatives for the visualization of the melanin concentrating hormone receptor 1

M Zeilinger, C Philippe, M Dumanic, F Pichler, J Pilz, M Hacker, W Wadsak, M Mitterhauser

A14 Reducing time in quality control leads to higher specific radioactivity of short-lived radiotracers

L Nics, B Steiner, M Hacker, M Mitterhauser, W Wadsak

A15 In vitro 11C-erlotinib binding experiments in cancer cell lines with epidermal growth factor receptor mutations

A Traxl, Thomas Wanek, Kushtrim Kryeziu, Severin Mairinger, Johann Stanek, Walter Berger, Claudia Kuntner, Oliver Langer

A16 7-[11C]methyl-6-bromopurine, a PET tracer to measure brain Mrp1 function: radiosynthesis and first PET evaluation in mice

S Mairinger, T Wanek, A Traxl, M Krohn, J Stanek, T Filip, M Sauberer, C Kuntner, J Pahnke, O Langer

A17 18F labeled azidoglucose derivatives as “click” agents for pretargeted PET imaging

D Svatunek, C Denk, M Wilkovitsch, T Wanek, T Filip, C Kuntner-Hannes, J Fröhlich, H Mikula

A18 Bioorthogonal tools for PET imaging: development of radiolabeled 1,2,4,5-Tetrazines

C Denk, D Svatunek, T Wanek, S Mairinger, J Stanek, T Filip, J Fröhlich, H Mikula, C Kuntner-Hannes

A19 Preclinical evaluation of [18F]FE@SUPPY- a new PET-tracer for oncology

T Balber, J Singer, J Fazekas, C Rami-Mark, N Berroterán-Infante, E Jensen-Jarolim, W Wadsak, M Hacker, H Viernstein, M Mitterhauser

A20 Investigation of Small [18F]-Fluoroalkylazides for Rapid Radiolabeling and In Vivo Click Chemistry

C Denk, D Svatunek, B Sohr, H Mikula, J Fröhlich, T Wanek, C Kuntner-Hannes, T Filip

A21 Microfluidic 68Ga-radiolabeling of PSMA-HBED-CC using a flow-through reactor

S Pfaff, C Philippe, M Mitterhauser, M Hartenbach, M Hacker, W Wadsak

A22 Influence of 24-nor-ursodeoxycholic acid on hepatic disposition of [18F]ciprofloxacin measured with positron emission tomography

T Wanek, E Halilbasic, M Visentin, S Mairinger, B Stieger, C Kuntner, M Trauner, O Langer

A23 Automated 18F-flumazenil production using chemically resistant disposable cassettes

P Lam, M Aistleitner, R Eichinger, C Artner

A24 Similarities and differences in the synthesis and quality control of 177Lu-DOTA-TATE, 177Lu -HA-DOTA-TATE and 177Lu-DOTA-PSMA (PSMA-617)

H Eidherr, C Vraka, A Haug, M Mitterhauser, L Nics, M Hartenbach, M Hacker, W Wadsak

A25 68Ga- and 177Lu-labelling of PSMA-617

H Kvaternik, R Müller, D Hausberger, C Zink, RM Aigner

A26 Radiolabelling of liposomes with 67Ga and biodistribution studies after administration by an aerosol inhalation system

U Cossío, M Asensio, A Montes, S Akhtar, Y te Welscher, R van Nostrum, V Gómez-Vallejo, J Llop

A27 Fully automated quantification of DaTscan SPECT: Integration of age and gender differences

F VandeVyver, T Barclay, N Lippens, M Troch

A28 Lesion-to-background ratio in co-registered 18F-FET PET/MR imaging – is it a valuable tool to differentiate between low grade and high grade brain tumor?

L Hehenwarter, B Egger, J Holzmannhofer, M Rodrigues-Radischat, C Pirich

A29 [11C]-methionine PET in gliomas - a retrospective data analysis of 166 patients

N Pötsch, I Rausch, D Wilhelm, M Weber, J Furtner, G Karanikas, A Wöhrer, M Mitterhauser, M Hacker, T Traub-Weidinger

A30 18F-Fluorocholine versus 18F-Fluorodeoxyglucose for PET/CT imaging in patients with relapsed or progressive multiple myeloma: a pilot study

T Cassou-Mounat, S Balogova, V Nataf, M Calzada, V Huchet, K Kerrou, J-Y Devaux, M Mohty, L Garderet, J-N Talbot

A31 Prognostic benefit of additional SPECT/CT in sentinel lymph node mapping of breast cancer patients

S Stanzel, G Pregartner, T Schwarz, V Bjelic-Radisic, B Liegl-Atzwanger, R Aigner

A32 Evaluation of diagnostic value of TOF-18F-FDG PET/CT in patients with suspected pancreatic cancer

S Stanzel, F Quehenberger, RM Aigner

A33 New quantification method for diagnosis of primary hyperpatahyroidism lesions and differential diagnosis vs thyropid nodular disease in dynamic scintigraphy

A Koljević Marković, Milica Janković, V Miler Jerković, M Paskaš, G Pupić, R Džodić, D Popović

A34 A rare case of diffuse pancreatic involvement in patient with merkel cell carcinoma detected by 18F-FDG

MC Fornito, D Familiari

A35 TSH-stimulated 18F-FDG PET/CT in the diagnosis of recurrent/metastatic radioiodine-negative differentiated thyroid carcinomas in patients with various thyroglobuline levels

P Koranda, H Polzerová, I Metelková, L Henzlová, R Formánek, E Buriánková, M Kamínek

A36 Breast Dose from lactation following I131 treatment

WH Thomson, C Lewis

A37 A new concept for performing SeHCAT studies with the gamma camera

WH Thomson, J O’Brien, G James, A Notghi

A38 Whole body F-18-FDG-PET and tuberculosis: sensitivity compared to x-ray-CT

H Huber, I Stelzmüller, R Wunn, M Mandl, F Fellner, B Lamprecht, M Gabriel

A39 Emerging role 18F-FDG PET-CT in the diagnosis and follow-up of the infection in heartware ventricular assist system (HVAD)

MC Fornito, G Leonardi

A40 Validation of Poisson resampling software

WH Thomson, J O’Brien, G James

A41 Protection of PET nuclear medicine personnel: problems in satisfying dose limit requirements

J Hudzietzová, J Sabol, M Fülöp

Effectiveness and side-effects of peptide receptor radionuclide therapy for neuroendocrine neoplasms in Germany: A multi-institutional registry study with prospective follow-up

BACKGROUND

Monocentric and retrospective studies indicate effectiveness of peptide receptor radionuclide therapy targeting somatostatin receptors of neuroendocrine neoplasms. We assessed overall and progression-free survival and adverse events of peptide receptor radionuclide therapy by a multi-institutional, board certified registry with prospective follow-up in five centres in Germany.

METHODS

A total of 450 patients were included and followed for a mean of 24.4 months. Most patients had progressive low- or intermediate grade neuroendocrine neoplasms and 73% were pretreated with at least one therapy. Primary neuroendocrine neoplasms were mainly derived of pancreas (38%), small bowel (30%), unknown primary (19%) or bronchial system (4%). Patients were treated with Lutetium-177 in 54%, with Yttrium-90 in 17% and with both radionuclides in 29%. Overall and progression-free survival was determined with Kaplan-Meier curves and uni-variate log rank test Cox models.

FINDINGS

Median overall survival of all patients was 59 (95% confidence interval [CI] 49-68.9) months. Overall survival was significantly inferior in the patients treated with Yttrium-90 solely (hazard ratio, 3.22; 95% CI, 1.83-5.64) compared to any peptide receptor radionuclide therapy with Lutetium-177. Grade II (hazard ratio, 2.06; 95% CI, 0.79-5.32) and grade III (hazard ratio, 4.22; 95% CI, 1.41-12.06) neuroendocrine neoplasms had significantly worse overall survival than grade I neuroendocrine neoplasms. Patients with small neuroendocrine neoplasms of small bowel had significantly increased survival (hazard ratio, 0.39; 95% CI, 0.18-0.87) compared to neuroendocrine neoplasms of other locations. Median progression-free survival was 41 (35.9-46.1) months and significantly inferior in patients treated with Yttrium solely (hazard ratio, 2.7; 95% CI, 1.71-4.55). Complete remission was observed in 5.6% of patients, 22.4% had a partial remission, 47.3% were stable and 4% were progressive as best response. Adverse events of bone marrow and kidney function higher than grade III occurred in 0.2-1.5% of patients.

INTERPRETATION

These results indicate that peptide receptor radionuclide therapy is a highly effective therapy for patients with low to intermediate grade neuroendocrine neoplasms with minor adverse events.

The Role of Positron Emission Tomography With (68)Gallium (Ga)-Labeled Prostate-specific Membrane Antigen (PSMA) in the Management of Patients With Organ-confined and Locally Advanced Prostate Cancer Prior to Radical Treatment and After Radical Prostatectomy

The role of positron emission tomography (PET) with (68)Gallium (Ga)-labeled prostate-specific membrane antigen (PSMA) imaging for prostate cancer is gaining prominence. Current imaging strategies, despite having progressed significantly, have limitations, in particular their ability to diagnose metastatic lymph node involvement. Preliminary results of PET with (68)Ga-labeled PSMA have shown encouraging results, particularly in the recurrent prostate cancer setting. Furthermore, the ability of PET with (68)Ga-labeled PSMA of playing a dual diagnostic and therapeutic setting (theranostics) is currently being investigated as well. PET with (68)Ga-labeled PSMA certainly has a role to play in bridging some of the voids in contemporary prostate cancer imaging tools.

[Peptide receptor radionuclide therapy for patients with somatostatin receptor expressing tumours. German Guideline (S1)]

This document describes the guideline for peptide receptor radionuclide therapy (PRRT) published by the German Society of Nuclear Medicine (DGN) and accepted by the Association of the Scientific Medical Societies in Germany (AWMF) to be included in the official AWMF Guideline Registry. These recommendations are a prerequisite for the quality management in the treatment of patients with somatostatin receptor expressing tumours using PRRT. They are aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRT and to deliver the treatment in a safe and effective manner. The recommendations are based on an interdisciplinary consensus. The document contains background information and definitions and covers the rationale, indications and contraindications for PRRT. Essential topics are the requirements for institutions performing the therapy, e. g. presence of an expert for medical physics, intense cooperation with all colleagues involved in the treatment of a patient, and a certificate of instruction in radiochemical labelling and quality control are required. Furthermore, it is specified which patient data have to be available prior to performance of therapy and how treatment has to be carried out technically. Here, quality control and documentation of labelling are of great importance. After treatment, clinical quality control is mandatory (work-up of therapy data and follow-up of patients). Essential elements of follow-up are specified in detail. The complete treatment inclusive after-care has to be realised in close cooperation with the involved medical disciplines. Generally, the decision for PRRT should be undertaken within the framework of a multi-disciplinary tumour board.

The search for the primary tumor in metastasized gastroenteropancreatic neuroendocrine neoplasm

Gastroenteropancreatic neuroendocrine tumors (NETs) often present as liver metastasis from a carcinoma of unknown primary. We recently showed that primary NETs from the pancreas, small intestine and stomach as well as their respective liver metastases differ from each other by the expression profile of the three genes CD302, PPWD1 and ABHB14B. The gene and protein expression of CD302, PPWD1, and ABHB14B was studied in abdominal NET metastases to identify the site of the respective primary tumors. Cryopreserved tissue from NET metastases collected in different institutions (group A: 29, group B: 50, group C: 132 specimens) were examined by comparative genomic hybridization (Agilent 105 K), gene expression analysis (Agilent 44 K) (groups A and B) and immunohistochemistry (group C). The data were blindly evaluated, i.e. without knowing the site of the primary. Gene expression analysis correctly revealed the primary in the ileum in 94 % of the cases of group A and in 58 % of group B. A pancreatic primary was predicted in 83 % (group A) and 20 % (group B), respectively. The combined sensitivity of group A and B was 75 % for ileal NETs and 38 % for pancreatic NETs. Immunohistochemical analysis of group C revealed an overall sensitivity of 80 %. Gene and protein expression analysis of CD302 and PPWD1 in NET metastases correctly identifies the primary in the pancreas or the ileum in 80 % of the cases, provided that the tissue is well preserved. Immunohistochemical profiling revealed CD302 as the best marker for ileal and PPWD1 for pancreatic detection.

[Pulmonary neuroendocrine neoplasms]

The pulmonary neuroendocrine neoplasms originate from the enterochromaffin cells which are diffusely distributed in the body. The incidence of these tumors has increased significantly in recent decades due to the available diagnostics. They make up about 1-2% of all lung tumors and 20-30% of all neuroendocrine neoplasms. The current WHO classification from 2004 divides them into typical carcinoids (TC), atypical carcinoids (AC), large cell neuroendocrine carcinomas (LCNEC) and small cell carcinomas (SCLC). The major neuroendocrine biomarkers are chromogranin A, synaptophysin and CD56. TC have a low mitotic rate of <2 mitoses/2mm(2) (10 HPF), whereas the mitotic rate of the AC is 2-10 mitoses/2 mm(2) (10 HPF). The Ki-67 staining is helpful to distinguish typical and atypical carcinoids from the highly malignant LCNEC and SCLC. Clinically, the patient presents usually with cough, hemoptysis or bronchial obstruction. The occurrence of a carcinoid or Cushing's syndrome and a tumor-associated acromegaly are rare. Surgical resection with radical lymph node dissection is the treatment of choice for achieving long-term survival. Endoscopic resection of the endobronchial tumor growth is a good alternative for inoperable endobronchially localized tumors. Peptide receptor radionuclide therapy (PRRT) is a promising treatment option for patients with metastatic or unresectable pulmonary neuroendocrine tumors. New targeted therapies using angiogenesis inhibitors, mTOR inhibitors, and tyrosine kinase inhibitors are being tested for their effectiveness in many previous studies. Typical carcinoid tumors metastasize less frequently than AC, the 5-year survival rate of patients with TC being over 90%. Patients with AC have a 5-year survival rate between 35% and 87%. The highly malignant LCNEC and SCLC, on the other hand, have a 5-year survival rate between 15% and 57%, and <5% respectively. The increasing number of therapeutic options and diagnostic procedures requires a multidisciplinary approach and decision-making in multidisciplinary tumor conferences to ensure a personalized treatment approach. Therefore patients with a neuroendocrine neoplasm of the lung should be treated in specialized centers.

[The relevance of PET/CT for the surgical management of neuroendocrine neoplasms]

Neuroendocrine neoplasms (NEN) are rare malignancies with a wide spectrum of metastatic potential which originate from the endocrine cells of the body and express somatostatin receptors. The (68)gallium somatostatin receptor positron emission tomography-computed tomography (PET/CT) technique is the most sensitive method of assessment of well-differentiated NENs and for the detection of cancer of unknown primary (CUP syndrome) NENs. Imaging with 18F-fluorodeoxyglucose (18F-FDG PET/CT) is indicated in poorly differentiated neuroendocrine carcinomas. The receptor-dependent imaging of NENs has a decisive impact on further management.

[Hereditary syndromes of neuroendocrine tumours]

Diffuse localised neuroendocrinal cells represent the largest population of endocrinally active cells and can degenerate to malignant neuroendocrine tumours (NET). In this review the most important hereditary syndromes that predispose for endocrine and neuroendocrine tumours are presented and discussed. NET occur mainly as sporadic tumours. Current investigations on the pathogenesis of sporadic neuroendocrine tumours have revealed a close relationship between hereditary and sporadic neuroendocrine tumours. In the course of hereditary syndromes, such as multiple endocrine neoplasia, endocrine and neuroendocrine tumours as well as non-endocrine neoplasias can occur. In order to recognise these syndromes in good time a knowledge of the predisposing syndromes and their cardinal symptoms is essential. In this way not only individualised diagnosis and therapy can be planned but also an appropriate early management of first degree relatives can be initiated.

The joint IAEA, EANM, and SNMMI practical guidance on peptide receptor radionuclide therapy (PRRNT) in neuroendocrine tumours

Peptide receptor radionuclide therapy (PRRNT) is a molecularly targeted radiation therapy involving the systemic administration of a radiolabelled peptide designed to target with high affinity and specificity receptors overexpressed on tumours. PRRNT employing the radiotagged somatostatin receptor agonists (90)Y-DOTATOC ([(90)Y-DOTA(0),Tyr(3)]-octreotide) or (177)Lu-DOTATATE ([(177)Lu-DOTA(0),Tyr(3),Thr(8)]-octreotide or [(177)Lu-DOTA(0),Tyr(3)]-octreotate) have been successfully used for the past 15 years to target metastatic or inoperable neuroendocrine tumours expressing the somatostatin receptor subtype 2. Accumulated evidence from clinical experience indicates that these tumours can be subjected to a high absorbed dose which leads to partial or complete objective responses in up to 30 % of treated patients. Survival analyses indicate that patients presenting with high tumour receptor expression at study entry and receiving (177)Lu-DOTATATE or (90)Y-DOTATOC treatment show significantly higher objective responses, leading to longer survival and improved quality of life. Side effects of PRRNT are typically seen in the kidneys and bone marrow. These, however, are usually mild provided adequate protective measures are undertaken. Despite the large body of evidence regarding efficacy and clinical safety, PRRNT is still considered an investigational treatment and its implementation must comply with national legislation, and ethical guidelines concerning human therapeutic investigations. This guidance was formulated based on recent literature and leading experts' opinions. It covers the rationale, indications and contraindications for PRRNT, assessment of treatment response and patient follow-up. This document is aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRNT and to deliver the treatment in a safe and effective manner. This document is largely based on the book published through a joint international effort under the auspices of the Nuclear Medicine Section of the International Atomic Energy Agency.

Vandetanib therapy in medullary thyroid cancer

The U.S. Food and Drug Administration (FDA) approved vandetanib in April 2011 for the treatment of unresectable, locally advanced or metastatic medullary thyroid cancer (MTC). In Europe it was approved in March 2012, but only for the treatment of aggressive and symptomatic MTC. This small molecule is a tyrosine kinase inhibitor of several growth factors involved in cellular proliferation and angiogenesis, including the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor receptors 2 and 3 (VEGFR-2, VEGFR-3). In addition, vandetanib is an inhibitor of the RET (rearranged during transfection) gene, a proto-oncogene often mutated in familial MTC. Since MTC is a rare disease, for which no previous medical therapies are approved, vandetanib is the first drug shown to be effective in a large phase III trial treating patients with metastatic or locally advanced MTC. Common adverse events are diarrhea, nausea, hypertension, headache and QT prolongation that are manageable and are commonly outweighed by the benefits of vandetanib in terms of delaying disease progression and inducing tumor response.

Comparing of IRS and Her2 as immunohistochemical scoring schemes in gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors (NET) are known for an overexpression of somatostatin receptors (SSTR). In light of very few and partially contradictory publications, the present study aims to achieve a definite immunohistochemical (IHC) quantification and assessment of the distribution of all five SSTR-subtypes on NET and to evaluate an implementable scoring system, comparing the immunoreactive score of Remmele and Stegner (IRS) to the Her2-score. In 21 patients 40 different tumor tissues were IHC analysed using polyclonal antibodies for SSTR1 and 3-5 and the monoclonal antibody UMB-1 for SSTR2A. SSTR expression was quantitatively evaluated according to HER2-score and IRS, correlated among each other and to the maximum standardized uptake value (SUVmax) in tumor lesions as measured by PET/CT using 68Ga-DOTA-NOC.

RESULTS

According to the IRS, the expression of SSTR2A and 3 predominated equally with 84%, followed by SSTR4 (44%) and SSTR1 and 5 (32%). With the Her2-scoring system the most frequent subtype was found to be SSTR2A (68%), followed by SSTR3 (64%), SSTR1 (44%), SSTR5 (40%), and SSTR4 (36%). The IRS-classification and the Her2-score were found to be statistically comparable, and their correlation is highly significant for each SSTR assessment (p<0.01).

CONCLUSION

The results of the analyses revealed heterogeneous expression patterns. SSTR2A and 3 were highly expressed, demonstrating the importance of SSTR for diagnostics and therapy. Relatively high frequency of SSTR3 and 4 on NET give reasons to try pansomatostatin analogues for therapy rather than concentrating only on the SSTR2A. Statistically, none of the immunohistochemical scores was superior. However, due the heterogeneity of the cytoplasmic staining justice we propose the IRS as a uniform scoring scheme for IHC NET diagnostic.

Nested stromal epithelial tumor of the liver--liver transplantation and follow-up

BACKGROUND

The nested stromal epithelial tumor (NSET) of the liver is a rare tumor entity which is being reported in young girls.

CASE REPORT

In our 16-year-old female patient, we have performed a liver transplantation (LTX) for a non-metastasizing non-resectable liver tumor. The patient was tumor free in the follow-up. At 28 months postoperatively, we detected lung metastases in the F18-FDG-PET/CT. The patient died 37 months after LTX from progressive pulmonary metastases.

CONCLUSION

LTX should not have been generally recommended for NSET. Further statements about the value of LTX for NSET will be possible only after evaluation of the course of the disease in a larger number of transplanted patients.

Concomitant lung and gastroenteropancreatic neuroendocrine tumors and the value of gallium-68 PET/CT

Well-differentiated neuroendocrine tumors (NETs) of the lung occur as typical and atypical carcinoids. Little is known about the biology of these tumors in respect of their ability to metastasize or the probability of development of concomitant neuroendocrine tumors. Here we report a patient diagnosed with a second neuroendocrine tumor of the ileum 4 years after curative resection of a typical carcinoid of the left lung. The intestinal neuroendocrine tumor was successfully detected by gallium-68 based somatostatin receptor positron emission tomography (PET)/computed tomography (CT) and surgically removed using gamma probe detection based on the same labeling. This case report underlines the utility of somatostatin receptor PET/CT based detection and follow-up of NETs.

Molecular imaging with ⁶⁸Ga-SSTR PET/CT and correlation to immunohistochemistry of somatostatin receptors in neuroendocrine tumours

PURPOSE

Somatostatin receptors (SSTR) are known for an overexpression in gastroenteropancreatic neuroendocrine tumours (GEP-NET). The aim of the present study was to find out if the receptor density predicted by the semi-quantitative parameters generated from the static positron emission tomography (PET/CT) correlated with the in vitro immunohistochemistry using a novel rabbit monoclonal anti-SSTR2A antibody (clone UMB-1) for specific SSTR2A immunohistochemistry and polyclonal antibodies for SSTR1 and 3-5.

METHODS

Overall 14 surgical specimens generated from 34 histologically documented GEP-NET patients were correlated with the preoperative (68)Ga-DOTA-NOC PET/CT. Quantitative assessment of the receptor density was done using the immunoreactive score (IRS) of Remmele and Stegner; the additional 4-point IRS classification for immunohistochemistry and standardized uptake values (SUV(max) and SUV(mean)) were used for PET/CT.

RESULTS

The IRS for SSTR2A and SSTR5 correlated highly significant with the SUV(max) on the PET/CT (p < 0.001; p < 0.05) and the IRS for SSTR2A with the SUV(mean) (p < 0.013). The level of SSTR2A score correlated significantly with chromogranin A staining and indirectly to the tumour grading.

CONCLUSION

The highly significant correlation between SSTR2A and SSTR5 and the SUV(max) on the (68)Ga-DOTA-NOC PET/CT scans is concordant with the affinity profile of (68)Ga-DOTA-NOC to the SSTR subtypes and demonstrates the excellent qualification of somatostatin analogues in the diagnostics of NET. This study correlating somatostatin receptor imaging using (68)Ga-DOTA-NOC PET/CT with immunohistochemically analysed SSTR also underlines the approval of therapy using somatostatin analogues, follow-up imaging as well as radionuclide therapy.

Therapeutic nuclear medicine in pediatric malignancy

The following review aims to provide contemporary information on therapeutic nuclear medicine procedures in paediatric malignancies. Neuroblastoma is the most common paediatric extra cranial solid cancer characterized by meta-iodobenzylguanidine (mIBG) avidity in >/=90% of patients. There exists approximately a 30-year experience with I-131-mIBG treatment. Ongoing efforts include a more standardized approach including dosimetric data for patient selection and treatment guidance of I-131-mIBG therapy. Neuroendocrine tumours (NETs) are very rare neoplasms in the paediatric population accounting for <1% of all paediatric malignancies. These neoplasms are characterized by the presence of neuroamine uptake mechanisms and/or peptide receptors at the cell membrane. These features constitute the basis of the clinical use of peptide receptor radionuclide therapy (PRRNT) using radiolabeled somatostatin analogues. Osteosarcoma is the most common primary bone tumour in children usually treated with chemotherapy and surgery. In palliative situations bone seeking radionuclide therapies (strontium-89 [Sr-89], rhenium-186 hydroxyethylene diphosphonate [Rh-186 HEDP] and Samarium-153-ethylene diamine tetramethylene phosphonic acid [Sm-153-EDTMP]) may be offered to patients with painful metastatic osteosarcoma or in case of recurrent bone sites inaccessible to local therapies (surgery, external irradiation). Thyroid cancer is a rare childhood malignancy with an approximate incidence of 0.54 per 100000 per year but is the most frequent tumour of endocrine glands in children and adolescents. Management includes radioiodine therapy but there are some distinct differences in comparison to adult thyroid cancer management.

Biodistribution of the Ga-68 labeled somatostatin analogue DOTA-NOC in patients with neuroendocrine tumors: characterization of uptake in normal organs and tumor lesions

AIM

The aim of the study was 1) to determine the normal biodistribution of radiolabeled somatostatin analogue (68)Ga DOTA-NOC; 2) to establish the range of its uptake in liver, bone and lymph node metastases in patients with NET, 3) to establish the cut-off value for differentiating between physiological uptake and tumor related sstr expression in the processus uncinatus of pancreas.

METHODS

Maximum standardized uptake values (SUV(max)) of (68)Ga DOTA-NOC were determined in normal organs of 89 NET patients undergoing receptor PET/CT. In addition, SUV(max) of primary pancreatic neuroendocrine tumors (pNET), liver, bone and lymph node metastases were evaluated.

RESULTS

SUV(max) (mean + or - standard deviation) were determined in: pituitary gland 2.6 + or - 1.3, thyroid: 3.4 + or - 1.4, lung: 0.9 + or - 0.8, normal liver: 6.9 + or - 2 , spleen: 22.0 + or - 10.0, adrenal 6.0 + or - 2.5, kidney: 12.9 + or - 3.8, gastrointestinal tract 2.3 + or - 1.0, gluteal muscle:1.0 + or - 0.3, femur 0.8 + or - 0.3, blood pool 2.6 + or - 1.2 and processus uncinatus of pancreas 5.8 + or - 2.0. SUV(max) of (68)Ga DOTA-NOC was 19.6 + or - 13.4 (N.=200) in liver metastases, 12.5 + or - 10 (N.=67) in lymph nodes metastasis, 9.5 + or - 6.0 (N.=78) in bone lesions, and 20.8 + or - 10.8 (N.=26) in pancreatic neuroendocrine primary tumors. Target to non target (T/NT) ratios were 3.4 + or - 2.3 for liver metastases (with normal

CONCLUSIONS

There is a broad range of sstr expression in metastastic lesions and in pNET. The splenic uptake of (68)Ga DOTA-NOC is highly variable. (68)Ga DOTA-NOC is an excellent tracer for imaging somatostatin receptor positive tumors, which, due to the high target to non-target ratios, allows the detection of very small lesions, especially of lymph node and bone metastases.

Are radiogallium-labelled DOTA-conjugated somatostatin analogues superior to those labelled with other radiometals?

PURPOSE

Gallium-68 is a metallic positron emitter with a half-life of 68 min that is ideal for the in vivo use of small molecules, such as [68Ga-DOTA,Tyr3]octreotide, in the diagnostic imaging of somatostatin receptor-positive tumours. In preclinical studies it has shown a striking superiority over its 111In-labelled congener. The purpose of this study was to evaluate whether third-generation somatostatin-based, radiogallium-labelled peptides show the same superiority.

METHODS

Peptides were synthesised on solid phase. The receptor affinity was determined by in vitro receptor autoradiography. The internalisation rate was studied in AR4-2J and hsst-HEK-transfected cell lines. The pharmacokinetics was studied in a rat xenograft tumour model, AR4-2J.

RESULTS

All peptides showed high affinities on hsst2, with the highest affinity for the Ga(III)-complexed peptides. On hsst3 the situation was reversed, with a trend towards lower affinity of the Ga(III) peptides. A significantly increased internalisation rate was found in sst2-expressing cells for all 67Ga-labelled peptides. Internalisation into HEK-sst3 was usually faster for the 111In-labelled peptides. No internalisation was found into sst5. Biodistribution studies employing [67Ga-DOTA,1-Nal3]octreotide in comparison to [111In-DOTA,1-Nal3]octreotide and [67Ga-DOTA,Tyr3]octreotide showed a significantly higher and receptor-mediated uptake of the two 67Ga-labelled peptides in the tumour and somatostatin receptor-positive tissues. A patient study illustrated the potential advantage of a broad receptor subtype profile radiopeptide over a high-affinity sst2-selective radiopeptide.

CONCLUSION

This study demonstrates that 67/68Ga-DOTA-octapeptides show distinctly better preclinical, pharmacological performances than the 111In-labelled peptides, especially on sst2-expressing cells and the corresponding animal models. They may be excellent candidates for further development for clinical studies.

Korrelation histologischer und nuklearmedizinischer Befunde der Tumorregression in behandelten bösartigen Lungentumoren

CT cannot provide useful information in a timely manner after neoadjuvant treatment. To evaluate the role of (18)F FDG PET after neoadjuvant chemoradiation for early therapy response and its effect on survival as compared to histopathologic tumor response, findings in 32 patients were analyzed prospectively in an ongoing multicenter trial (LUCAS-MD).

INCLUSION CRITERIA

histologically confirmed NSCLC stage IIIA/IIIB. Neoadjuvant treatment: 2-3 cycles with paclitaxel/carboplatin and a block of chemoradiation followed by surgery. Pretherapeutic staging: PET scan in addition to a spiral CT and/or MRI. Second PET scan after completion of neoadjuvant therapy prior to surgery. Documentation of lymph node involvement. Assessment of SUV and the metabolic tumor index for primary tumor and metastatic lymph nodes. Image fusion of PET with CT data followed by molecular radiation treatment planning. Evaluation of histologic regression grade and correlation with PET for primary tumor and each lymph node location. All patients (10/32) with complete response in lymph node metastases detected by PET prior to surgery, had no vital tumor cells (i.e. histologic regression grade/RG III, sensitivity 100%). In primary tumors showing complete response, the RG was IIb or III, in one patient IIa (false negative in PET). False positive findings in PET are due to inflammation (5 patients, histologically confirmed). Univariate analyses: actuarial tumor-specific survival for complete metabolic remission vs. incomplete remission after 24 months: 76 vs. 20% (p=0,0079); for RG III/IIb vs. RG IIa/I after 24 months: 63 vs. 36% (p=0,0123).(18)F FDG PET precedes CT in measuring the tumor response and may predict (long term) therapeutic outcome in stage III NSCLC. Histologic regression grade correlates well with metabolic remission as detected by PET.

Position of nuclear medicine modalities in the diagnostic workup of cancer patients: lung cancer

This review summarizes the current literature and tries to define the status of nuclear medicine in the clinical workup of lung cancer patients. Nuclear medicine procedures and positron emission tomography (PET) with the EMEA-approved radiopharmaceutical fluorodeo-xyglucose (FDG) are indicated for the characterization of lung lesions; the nodal staging of non-small cell lung cancer (NSCLC); the detection of distant metastases; and for the diagnosis of recurrent disease. Recent studies have shown the clinical efficacy of nuclear medicine and especially of FDG-PET in the workup of lung cancer patients and its significant impact on patients' management. Conventional nuclear medicine procedures are established for the pre-therapeutic assessment of pulmonary perfusion and function (lung perfusion and ventilation scintigraphy) and for the detection of bone metastases (skeletal scintigraphy). In studies in thousands of patients, FDG-PET has been proved to be the most accurate non-invasive diagnostic test for the characterization of lung nodules and masses. It can be recommended at least for patients with increased risk at surgery. FDG-PET should be applied in candidates for surgery of lung cancer, as mediastinoscopy may be omitted if PET shows no metastases in the mediastinum, and because FDG-PET avoids futile surgery by a more accurate selection of patients, especially by the detection of unexpected distant metastases. In candidates for thoracic radiotherapy, FDG-PET can help to exclude extrathoracic disease which needs systemic treatment and to better define the target volume for radiation therapy. The time has come for FDG-PET to find its place in new guidelines for the workup of lung cancer patients.

Radioinmunolocalización de tumores de cabeza y cuello con un nuevo anticuerpo monoclonal contra el receptor del EGF. Resultados preliminares

OBJECTIVE

To show the results of Radioimmunodetection (RID) using Cuban monoclonal antibody (MoA) anti-egf-ior-egf-r3 labeled with 99mTc for the detection of primary tumors and/or metastases of head and neck epithelial malignant tumors.

MATERIAL AND METHODS

Thirteen patients aged from 16-62 years (mean: 54.8 years) with primary tumors and metastases in the regional cervical lymph nodes were retrospectively evaluated. The labelling dose was 1480-2220 MBq (40-60 mCi). Planar images were performed after 10 minutes and together with SPECT images after 18-24 hours following MoA administration. The matrix was 128 x 128. SPECT images were reconstructed using the Butterworth 4/16 filter. A positive result was defined when the lesions were visualized.

RESULTS

RID localized 11 of the known primary tumors in the 13 patients studied. In the two other patients, in whom the primary tumor site was unknown, cervical lymph node metastases were found. The results of 3 of the RID were false negative but in the other 10, RID was able to localize the primary tumor and cervical lymph node metastases. Sensitivity was 77 % and the predictive positive value was 100 %.

CONCLUSIONS

The results of this study show that the Cuban MoA ior-egf-r3 can be employed for RID of primary head and neck tumors and their metastases. The radiation dose is adequate for RID.

Evaluation of therapy response in breast and ovarian cancer patients by positron emission tomography (PET)

Positron emission tomography (PET) has the potential to contribute significantly to treatment planning and to the evaluation of response to therapy in patients with cancer. For disease recurrence PET imaging provides information non-invasively. The final goal is to biologically characterize an individual patient's tumor and to predict the response to treatment at the earliest possible time. Since the development of neoadjuvant chemotherapy, PET has been proved to be the most sensitive and accurate imaging technique for early therapy response evaluation of breast tumors. Quantitative and/or semi-quantitative PET studies yield valuable information in breast cancer regarding prognosis and response to chemohormontherapy in a timely fashion. In ovarian cancer, up to now only few studies have been performed applying PET techniques for the evaluation of treatment response. These preliminary studies indicate that serial assessment of tumor metabolism by FDG-PET early during effective chemotherapy may predict subsequent response to such therapy. PET studies can be repeated without any side-effects and with low radiation exposure and results can be directly correlated with clinical laboratory data and histology. The role of PET in the context of patient management and the cost-effectiveness of this approach needs further evaluation. Therapy monitoring by PET could help to optimize neoadjuvant therapy protocols and to avoid ineffective preoperative therapy in non-responders, but this has to be proven in a larger number of patients and in different neoadjuvant settings such as chemotherapy, radiation therapy, hormone therapy or a combination of these.

Induction of CA125-specific B and T cell responses in patients injected with MAb-B43.13--evidence for antibody-mediated antigen-processing and presentation of CA125 in vivo

The murine monoclonal anti-CA125 antibody MAb-B43.13 has previously been administered as an immunoscintigraphic agent in order to monitor recurrence of ovarian cancer in patients, and a long-term follow-up demonstrated a survival benefit for these patients. The clinical benefit was initially attributed to the activation of the idiotypic network. The objective of this study was to investigate the role of CA125-MAb-B43.13 immune complex formation on the induction of CA125-specific immune responses. Analysis of patient serum samples from pharmacokinetic studies demonstrated that the antibody forms immune complexes with CA125 in circulation within 30 minutes of injection. Induction of humoral and cellular anti-CA125 responses correlated with the amount of circulating CA125 antigen present at time of antibody injection. Subsequent to the injection of MAb-B43.13, the patients generated anti-CA125 antibodies that were directed against various epitopes on the antigen and were not restricted to the specific epitope recognized by MAb-B43.13. The generation of CA125-specific B and T cell responses after MAb-B43.13 injection correlated with improved survival. The influence of circulating CA125 for the induction of CA125-specific immune responses and the multi-epitopic nature of the human anti-CA125 antibodies suggest that the majority of these antibodies were not induced via the idiotypic network but by the autologous antigen itself. Since antibody and T cell responses to CA125 were not present before injection of MAb-B43.13, it is hypothesized that complex formation of MAb-B43.13 with circulating antigen triggers the induction of CA125-specific immune responses.

[Pilot study with the monoclonal antibody IOR-C5 as a potential agent of radioimmunoscintigraphy in colorectal cancer]

IOR C-5 is a G1 immunoglobulin type intact murine monoclonal antibody (MAb) that was developed in the Center of Molecular Immunology in Havana City, Cuba. In immunohistochemical studies, this demonstrated a significant affinity for the epithelial tissues so that it was used in a pilot clinical study to perform a radioimmunoscintigraphy of the colorectal primary tumors and their locoregional recurrences. It was labeled with 99mTc using the Schwarz method, with a > 95% performance. Planar images of the chest, abdomen and pelvis were performed at 10 minutes, 4-6 hours and 18-24 hours post-injection in the anterior and posterior projections and the SPECT was performed 4-6 hours and 18-24 hours post-injection of 1.85 GBq 99mTC. This study has aimed to verify in vivo the capacity of ior-C5 MAb to accumulate in the malignant colorectal lesions. ior-C5 accumulated in 5 out of the 7 patients who were studied and who were suffering from colorectal cancer or in whom there was suspicion of recurrence. There was a negative case of primary tumors, which was an adenocarcinoma in situ in a tubular-papillary adenoma. The second case with a negative radioimmunoscintigraphy was a true negative case.

CONCLUSIONS

It can be concluded that even though the number of patients is quite low, ior-C5 fulfilled the expectations of recognizing the epitope expressed in colorectal tumors in an in vivo human environment.

Staging of the neck in patients with oral cavity squamous cell carcinomas: a prospective comparison of PET, ultrasound, CT and MRI

BACKGROUND

The choice of treatment in patients with oral malignancies depends on accurate pretreatment staging and particularly the detection of lymph node involvement. Therefore staging of the neck should be as accurate as possible.

PATIENTS

One hundred and six patients with histologically proven squamous cell carcinoma of the oral cavity.

STUDY DESIGN

In a prospective study, PET using fluoro-desoxy-glucose (18F-FDG), ultrasound, CT and MRI of head and neck were compared with the postoperative histologic tissue evaluation. Two thousand one hundred and ninety-six neck lymph nodes of 106 patients were investigated. In all patients the tumour was resected and a lymph node dissection was performed.

RESULTS

The diagnostic procedures showed the following results when compared with the histological findings: PET: sensitivity 70%, specificity 82%, accuracy 75%; Ultrasound: 84%, 68%, 76%; CT: 66%, 74%, 70%; MRI: 64%, 69% 66%. Thus PET showed the highest specificity while ultrasound had the highest sensitivity compared with the other staging procedures. A nonsignificant correlation was found between the size of a lymph node metastasis and the ability to detect it. In 10 patients, second primary tumours or distant metastases were detected by PET only.

CONCLUSION

Due to the high number of small lymph node metastases from oral cavity carcinoma, the non-invasive neck staging methods are limited to a maximum accuracy of 76%. Elective neck treatment should be mandatory for all patients with squamous cell carcinoma of the oral cavity.

Intraoperative use of gamma-detecting probes to localize neuroendocrine tumors

Neuroendocrine tumors are characterized by the expression of different peptides and biogenic amines. These rare tumors tend to grow slowly and are notoriously difficult to localize, at least in the early stages. Surgical removal is the only definitive therapeutic option for neuroendocrine tumors and relief from hyperfunctional status. The effectiveness of surgical treatment is invariably dependent upon the complete surgical excision of all tumor tissue, because microscopic and occult disease not readily seen by the surgeon may remain in situ, leading to shortened survival. Therefore, pre- and intraoperative localization of the primary as well as of metastatic tumors is of utmost importance. Radioguided surgery (RGS) is an intraoperative technique that enables the surgeon to localize radiolabelled tissue based on the characteristics of the various tissues. Concerning gastroenteropancreatic tumors (GEP), intraoperative gamma probe examination is able to reveal small tumor sites accumulating (111In-DTPA-D-Phe1)-pentetreotide more efficiently (> 90%) than somatostatin receptor scintigraphy (68%-77%), because lesions with a size smaller than 5 mm in greatest dimension could be identified. Furthermore, RGS identified 57% more lesions when compared to the "palpating finger" of the surgeon. In medullary thyroid cancer (MTC), surgical removal of the tumor is the first and most efficient treatment of the disease. Persistent or increasing serum calcitonin and carcinoembryonic antigen (CEA) levels imply tumor recurrence after thyroid ablation. For imaging recurrent MTC many radiopharmaceuticals have been used to visualize tumor sites, but none of them has shown excellent sensitivity. Preoperative somatostatin receptor scintigraphy and intraoperative RGS in patients with recurrent MTC demonstrate only part of the tumor sites and cannot visualize small tumor sites (less than 10 mm). In comparison, RGS using 99mTc(V)-DMSA detects metastases with a size of 5 mm in diameter, whereas the "palpating finger" of the surgeon localized metastases with a size of more than 1 cm in diameter. In patients with recurrent MTC, intraoperative gamma probe examination is able to localize over 30% more tumor lesions when compared with conventional preoperative imaging modalities and surgical findings. MIBG scintigraphy is the most sensitive technique for the detection and staging of neuroblastoma (sensitivity 92%; specificity nearly 100%). Intraoperative RGS with iodine labelled MIBG has been developed to improve the definition of tumor limits or to localize small, nonpalpable tumors. Comparison of 123I- and 125I-labelled MIBG revealed a sensitivity of 91% and 92%, respectively; the specificity of 125I (85%) was significantly higher than that of 123I (55%). In addition to scintigraphy of the adrenal glands by precusors of adrenal hormones, imaging with a radiolabelled somatostatin analogue is possible; however, (111In-DTPA-D-Phe1)-pentetreotide is not specific for any adrenal disease or function and the relatively high radioligand accumulation in the kidneys limited the use for detection of tumors in the area of the adrenal glands.