Does positron emission tomography using 18-fluoro-2-deoxyglucose improve clinical staging of testicular cancer?--Results of a study in 50 patients

The evolution of PET imaging in renal, bladder, upper urinary tract urothelial, testicular and penile carcinoma - Today's impact, tomorrow's potential

INTRODUCTION

The advancement of hybrid PET/CT or PET/MRI imaging for non-prostate genitourinary cancers has not experienced the rapid progress of prostate cancer. Nevertheless, these neoplasms are aggressive and reliable imaging plays a pivotal role in enhancing patients' quality of life and prognosis.

AREAS COVERED

the main evidence regarding [18F]FDG and non-[18F]FDG PET/CT or PET/MRI in non-prostate uro-oncological malignancies are summarized and discussed. Moreover, potential future directions concerning PET imaging in these neoplasms are debated, with the aim to stimulate future research projects covering these fields.

EXPERT OPINION

In Renal Cell Carcinoma (RCC), [18F]FDG PET/CT demonstrates varying efficacy in staging, restaging, and prognostic stratification, but PSMA PET/CT is emerging as a potential game-changer, particularly in advanced, high-grade aggressive clear cell RCC. [18F]FDG PET/CT may see an increased use in N and M-staging of bladder cancer, as well as for detecting recurrence and response to neoadjuvant chemotherapy. Preliminary data regarding [68Ga]-FAPI also looks promising in this context. [18F]FDG PET/MRI could be useful for the T-staging of bladder cancer, while upper tract urothelial carcinoma still lacks of molecular imaging literature reports. In testicular and penile cancer [18F]FDG PET/CT has demonstrated its usefulness in several clinical settings, although experiences with non-[18F]FDG radiotracers are lacking.

The utility of cfDNA in TGCT patient management: a systematic review

Background:

Testicular germ cell tumors (TGCTs) are the most common young male malignancy with a steadily rising incidence. Standard clinical practice is radical orchidectomy of suspicious lumps followed by histopathological diagnosis and tumor subtyping. This practice can lead to complications and quality of life issues for the patients. Liquid biopsies, especially cell-free DNA (cfDNA), promised to be true surrogates for tissue biopsies, which are considered dangerous to perform in cases of testicular tumors. In this study, we have performed a systematic review on the potential of cfDNA in TGCT patient management, its potential challenges in translation to clinical application and possible approaches in further research.

Materials & Methods:

The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines on EuropePMC and PUBMED electronic databases, with the last update being on October 21, 2021. Due to the high heterogeneity in identified research articles, we have performed an overview of their efficacy.

Results:

Eight original articles have been identified on cfDNA in TGCT patients published from 2004 to 2021, of which six had more than one TGCT patient enrolled and were included in the final analysis. Three studies investigated cfDNA methylation, one has investigated mutations in cfDNA, two have investigated cfDNA amount, and one has investigated cfDNA integrity in TGCT. The sensitivity of cfDNA for TGCT was found to be higher than in serum tumor markers and lower than miR-371a-3p, with comparable specificity. cfDNA methylation analysis has managed to accurately detect teratoma in TGCT patients.

Conclusion:

Potential challenges in cfDNA application to TGCT patient management were identified. The challenges relating to the biology of TGCT with its low mutational burden and low cfDNA amounts in blood plasma make next-generation sequencing (NGS) methods especially challenging. We have also proposed possible approaches to help find clinical application, including a focus on cfDNA methylation analysis, and potentially solving the challenge of teratoma detection.

ACR Appropriateness Criteria® Staging and Surveillance of Testicular Cancer: 2021 Update

The staging and surveillance of testicular cancer is a complex topic, which integrates clinical, biochemical, and imaging components. The use of imaging for staging and surveillance of testicular cancer is individually tailored to each patient by considering tumor histology and prognosis. This document discusses the rationale for use of imaging by imaging modality during the initial staging of testicular seminoma and nonseminoma tumors and during the planned surveillance of stage IA and IB testicular cancer by histological subtype integrating clinical suspicion for disease recurrence in surveillance protocols. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

PET/CT limitations and pitfalls in urogenital cancers

Hybrid FDG PET/CT plays a vital role in oncologic imaging and has been widely adopted for the staging and restaging of a variety of malignancies. Its diagnostic value in urogenital malignancies is less well-known, not at least because of the variable FDG avidity of these tumor entities, the sites of these tumors, and technical challenges associated with sequential imaging of CT and PET. PET/CT interpretation thus can be especially challenging and is associated with many pitfalls, which can lead to both false-positive and false-negative diagnoses as well as incorrect assessment of metabolic change following therapy. Currently, FDG PET/CT is not the standard of care for the initial diagnosis or staging of early-stage or low-risk urogenital cancers; however, it can help evaluate distant metastatic disease, response to therapy, and disease recurrence in high-risk patients. Knowledge of imaging features of tumor metabolic avidity and pitfalls is essential for accurate interpretation.

PET imaging in urology: a rapidly growing successful collaboration

PURPOSE OF REVIEW

To discuss and highlight the recent findings in urological oncology focusing on nuclear medicine advances on imaging and therapy.

RECENT FINDINGS

Testicular tumors: F-FDG as the standard positron emission tomography (PET) tracer with proven good accuracy in detecting metastatic testicular cancer; urothelial cancer: good accuracy of F-FDG PET in detecting distant metastases but poor results in detecting local disease; prostate cancer: prostate-specific membrane antigen (PSMA) is a promising target for imaging prostate cancer with unprecedented accuracy in both staging and restaging and prospective studies were recently published. In castration-resistant prostate cancer, PSMA-targeting radionuclide therapy is showing potential as a curative possibility (e.g. using Lu-PSMA); renal cell cancer (RCC): besides FDG other PET radiotracers are under clinical evaluation (e.g. antibody-based molecular imaging, metabolic radiotracers and PSMA-based tracers). PSMA-based imaging may have applications in staging clear-cell RCC and in the selection and in the antiangiogenic treatment's response assessment. Possible role of PSMA-targeting radionuclide therapy?

SUMMARY

In urological oncology, the use of F-FDG has been limited by a generally low tumor uptake and physiological F-FDG excretion by the urinary system. Other radiotracers are increasing the urologist's portfolio allowing imaging of several biochemical pathways. Theragnostic possibilities are also under investigation thanks to PSMA-based tracers.

The metabolic landscape of urological cancers: New therapeutic perspectives

Deregulation of cell metabolism is an established cancer hallmark that contributes to tumor initiation and progression, as well as tumor heterogeneity. In solid tumors, alterations in different metabolic pathways, including glycolysis, pentose phosphate pathway, glutaminolysis and fatty acid metabolism, support the high proliferative rates and macromolecule biosynthesis of cancer cells. Despite advances in therapy, urothelial tumors still exhibit high recurrence and mortality rates, especially in advanced stages of disease. These tumors harbor gene mutations and expression patterns which play an important role in metabolic reprogramming. Taking into account the unique metabolic features underlying carcinogenesis in these cancers, new and promising therapeutic targets based on metabolic alterations must be considered. Furthermore, the combination of metabolic inhibitors with conventional targeted therapies may improve effectiveness of treatments. This review will summarize the metabolic alterations present in urological tumors and the results with metabolic inhibitors currently available.

Management of Stage II Germ Cell Tumors

There are several treatment approaches for stage II germ cell tumors (GCTs), and a thorough understanding of the staging classification and histologic differences in tumor biology and therapeutic responsiveness is critical to determine an effective, multimodal management strategy that involves urologists, medical oncologists, and radiation oncologists. This article discusses contemporary management strategies for stage II GCTs, including chemotherapy, radiotherapy, retroperitoneal lymph node dissection (RPLND), and surveillance. Patient selection, histology, and extent of lymphadenopathy drive management, and, as both treatment and detection strategies continue to emerge and be refined, the management of patients with stage II GCT continues to evolve.

The Warburg Effect Is Associated With Tumor Aggressiveness in Testicular Germ Cell Tumors

Testicular Germ Cell Tumors (TGCTs) are a rare group of neoplasms and the most common solid malignancy arising in young male adults. Despite the good response of these tumors to platinum-based chemotherapy, some patients are refractory to treatment and present poor clinical outcomes. During carcinogenesis and tumor development, cancer cells reprogram energy metabolism toward a hyper-glycolytic phenotype, an emerging hallmark of cancer. This phenomenon, known as the Warburg effect or aerobic glycolysis, involves overexpression of metabolism-related proteins, like glucose and monocarboxylate transporters, pH regulators and intracellular glycolytic enzymes. The metabolic profile of TGCTs is very little explored and, recently, this metabolic rewiring of cancer cells has been associated with aggressive clinicopathological characteristics of these tumors. The overexpression of monocarboxylate transporter 4 (MCT4) in TGCTs has been pointed out as a poor prognostic factor, as well as a promising therapeutic target. As a result, the main aim of the present study was to evaluate the prognostic value of key metabolism-related proteins in TGCTs. The immunohistochemical expressions of CD44 (as a monocarboxylate transporter chaperone), glucose transporter 1 (GLUT1), carbonic anhydrase IX (CAIX), hexokinase II (HKII) and lactate dehydrogenase V (LDHV) were evaluated in a series of 148 adult male patients with TGCTs and associated with clinicopathological parameters. In addition, paired normal tissues were also evaluated. The sample included 75 seminoma and 73 non-seminoma tumors. GLUT1 and CD44 expression was significantly increased in malignant samples when compared to paired normal samples. Conversely, HKII and LDHV expressions were significantly decreased in malignant samples. Concerning the clinicopathological values, CAIX expression was significantly associated with disease recurrence, while HKII expression was significantly associated with aggressive characteristics of TGCTs, including higher staging and non-seminoma histology. In conclusion, this study brings new insights on the metabolic characteristics of TGCTs, showing alterations in the expression of proteins related with the Warburg effect, as well as associations of the hyper-glycolytic and acid-resistant phenotype with aggressive clinicopathological parameters.

The clinicopathological significance of monocarboxylate transporters in testicular germ cell tumors

Background

Metabolic reprogramming is one of the hallmarks of cancer. The hyperglycolytic phenotype is often associated with the overexpression of metabolism-associated proteins, such as monocarboxylate transporters (MCTs). MCTs are little explored in germ cell tumors (GCTs), thus, the opportunity to understand the relevance of these metabolic markers and their chaperone CD147 in this type of tumor arises. The main aim of this study was to evaluate the expression of MCT1, MCT2, MCT4 and CD147 in testicular GCT samples and the clinicopathological significance of these metabolism related proteins.

Results

MCT1, MCT4 and CD147 were associated with higher stages, higher M and N stages and histological type, while MCT4 was also associated with higher risk stratification, presence of vascular invasion, and lower overall and event free survival. MCT4 silencing in JEG-3 had no significant effect in cell viability, proliferation and death, as well as extracellular levels of glucose and lactate. However, MCT4-silenced cells showed an increase in migration and invasion.

Conclusion

The proteins herein studied, with the exception of MCT2, were associated with characteristics of worse prognosis, lower global and event free survival of patients with GCTs. Also, in vitro MCT4 silencing stimulated cell migration and invasion.

Materials and Methods

Immunohistochemical expression was evaluated on samples from 149 adult patients with testicular GCT, arranged in Tissue Microarrays (TMAs), and associated with the clinicopathological data. Also, MCT4 silencing studies using siRNA were performed in JEG-3 cells.

The role of 18F-FDG PET/CT in the management of testicular cancers

OBJECTIVES

The aim of this study was to determine the utility of fluorine-18 fluorodeoxyglucose PET/computed tomography ((18)F-FDG PET/CT) in managing testicular cancer.

PATIENTS AND METHODS

Sixty-two patients (29 seminoma, 28 nonseminoma and five mixed) underwent 75 (18)F-FDG PET/CT scans (16 scans for primary staging, 44 for residual masses and 15 for rising tumour markers). Follow-up histology, clinical scans and tumour marker results were included for retrospective analysis.

RESULTS

(i) Primary staging: eight of 11 patients with equivocal CT scans had true-negative (18)F-FDG PET/CT scans. Five high-risk patients with normal stage 1 CT scans had negative (18)F-FDG PET/CT scans, but two subsequently relapsed. (ii) Residual masses: of the 20 scans interpreted as showing viable disease, five were false positive. Nineteen scans were negative (18 true negative and one false negative). (iii) Rising tumour markers: of the 15 scans, two were false negative and 13 were true positive.

CONCLUSION

(18)F-FDG PET/CT is helpful when primary staging CT scans are equivocal but insufficiently sensitive to predict relapse in high-risk patients with normal CT scans. With residual masses, a negative scan is rarely associated with relapse. (18)F-FDG PET/CT is helpful in defining recurrent disease in the majority of patients with rising tumour markers and negative CT scans.

PET/Computed Tomography in Renal, Bladder, and Testicular Cancer

Imaging plays an important role in the clinical management of cancer patients. Hybrid imaging with PET/computed tomography (CT) is having a broad impact in oncology, and in recent years PET/CT is beginning to have an impact in urooncology. In both bladder and renal cancers, there is a need to study the efficacy of other tracers than F-18 fluorodeoxyglucose (FDG), particularly tracers with limited renal excretion. Thus, new tracers are being introduced. This review focuses on the clinical role of FDG and other PET agents in renal, bladder, and testicular cancers.

Nuclear medicine in urological cancers: what is new?

ABSTRACT 

The diffusion of PET/computed tomography has opened up a new role for nuclear imaging in urological oncology. Prostate cancer is evaluated with choline (11C or 18F) PET due to a lack of sensitivity of 18F-fluorodeoxyglucose (FDG). However, many new tracers, such as 18F-fluorocyclobutane-1-carboxylic acid and 68Ga-prostate-specific membrane antigen, are under investigation, offering promising results in the particular setting of radically treated patients with biochemical relapse. The performance of 18F-FDG depends on the histological type; indeed, renal cell cancer may present variable metabolic uptake. In this field, mainly antibodies labeled with positron emitters are under clinical evaluation. Finally, 18F-FDG PET/computed tomography has been proven to show good accuracy in detecting metastatic testicular and bladder cancers, despite not having valid results in detecting local disease. The urological cancer diagnostic process is currently under continuous development.

Isolated femoral muscle and bone metastases rarely encountered in testicular seminoma

Isolated muscle and bone metastases are rarely encountered in patients with testicular seminomas. In the present study, a patient who was admitted with pain, loss of motion, and swelling in the right leg 20 months following surgery for stage I seminoma was presented. Hypermetabolic lesion was detected in the right femoral muscle and bone via positron emission tomography. After the presence of metastasis from seminoma was confirmed by biopsy, bleomycin, cisplatin, and etoposide, combination chemotherapy was administered to the patient.

PET/CT in Patients with Sarcoidosis or IgG4 Disease

Sarcoidosis as a distinct disease entity was diagnosed more than 100 years ago. The signs and symptoms of the disease are nonspecific, posing a challenge for early and accurate diagnosis. IgG4 disease or syndrome has various clinical manifestations, such as sclerosing pancreatitis, sclerosing cholangitis, prostatitis, tubulointerstitial nephritis, interstitial pneumonia, and enlargement of salivary glands. This article discusses the role of the different diagnostic imaging modalities in sarcoidosis and IgG4 disease, including radiographs, computed tomography, magnetic resonance imaging, and conventional nuclear medicine, with a special emphasis on positron emission tomography as a superior modality for assessing these inflammatory diseases.

2-¹⁸fluoro-deoxy-D-glucose positron emission tomography (FDG-PET) for postchemotherapy seminoma residual lesions: a retrospective validation of the SEMPET trial

BACKGROUND

2-¹⁸fluoro-deoxy-D-glucose positron emission tomography (FDG-PET) has been recommended in international guidelines in the evaluation of postchemotherapy seminoma residuals. Our trial was designed to validate these recommendations in a larger group of patients.

PATIENTS AND METHODS

FDG-PET studies in patients with metastatic seminoma and residual masses after platinum-containing chemotherapy were correlated with either the histology of the resected lesion(s) or the clinical outcome.

RESULTS

One hundred and seventy seven FDG-PET results were contributed. Of 127 eligible PET studies, 69% were true negative, 11% true positive, 6% false negative, and 15% false positive. We compared PET scans carried out before and after a cut-off level of 6 weeks after the end of the last chemotherapy cycle. PET sensitivity, specificity, negative predictive value (NPV), and positive predictive value were 50%, 77%, 91%, and 25%, respectively, before the cut-off and 82%, 90%, 95%, and 69% after the cut-off. PET accuracy significantly improved from 73% before to 88% after the cut-off (P=0.032).

CONCLUSION

Our study confirms the high specificity, sensitivity, and NPV of FDG-PET for evaluating postchemotherapy seminoma residuals. When carried out at an adequate time point, FDG-PET remains a valuable tool for clinical decision-making in this clinical setting and spares patients unnecessary therapy.

A validated bioanalytical HPLC method for pharmacokinetic evaluation of 2-deoxyglucose in human plasma

2-Deoxyglucose (2-DG), an analog of glucose, is widely used to interfere with glycolysis in tumor cells and studied as a therapeutic approach in clinical trials. To evaluate the pharmacokinetics of 2-DG, we describe the development and validation of a sensitive HPLC fluorescent method for the quantitation of 2-DG in plasma. Plasma samples were deproteinized with methanol and the supernatant was dried at 45°C. The residues were dissolved in methanolic sodium acetate-boric acid solution. 2-DG and other monosaccharides were derivatized to 2-aminobenzoic acid derivatives in a single step in the presence of sodium cyanoborohydride at 80°C for 45 min. The analytes were separated on a YMC ODS C₁₈ reversed-phase column using gradient elution. The excitation and emission wavelengths were set at 360 and 425 nm. The 2-DG calibration curves were linear over the range of 0.63-300 µg/mL with a limit of detection of 0.5 µg/mL. The assay provided satisfactory intra-day and inter-day precision with RSD less than 9.8%, and the accuracy ranged from 86.8 to 110.0%. The HPLC method is reproducible and suitable for the quantitation of 2-DG in plasma. The method was successfully applied to characterize the pharmacokinetics profile of 2-DG in patients with advanced solid tumors.

Fusion imaging: a novel staging modality in testis cancer

Objective: Computed tomography and chest radiographs provide the standard imaging for staging, treatment, and surveillance of testicular germ cell neoplasms. Positron emission tomography has recently been utilized for staging, but is somewhat limited in its ability to provide anatomic localization. Fusion imaging combines the metabolic information provided by positron emission tomography with the anatomic precision of computed tomography. To the best of our knowledge, this represents the first study of the effectiveness using fusion imaging in evaluation of patients with testis cancer.

Methods: A prospective study of 49 patients presenting to Walter Reed Army Medical Center with testicular cancer from 2003 to 2009 was performed. Fusion imaging was compared with conventional imaging, tumor markers, pathologic results, and clinical follow-up.

Results: There were 14 true positives, 33 true negatives, 1 false positive, and 1 false negative. Sensitivity, specificity, positive predictive value, and negative predictive value were 93.3, 97.0, 93.3, and 97.0% respectively. In 11 patient scenarios, fusion imaging differed from conventional imaging. Utility was found in superior lesion detection compared to helical computed tomography due to anatomical/functional image co-registration, detection of micrometastasis in lymph nodes (pathologic nodes < 1cm), surveillance for recurrence post-chemotherapy, differentiating fibrosis from active disease in nodes < 2.5cm, and acting as a quality assurance measure to computed tomography alone.

Conclusions: In addition to demonstrating a sensitivity and specificity comparable or superior to conventional imaging, fusion imaging shows promise in providing additive data that may assist in clinical decision-making.

FDG-PET probe-guided surgery for recurrent retroperitoneal testicular tumor recurrences

AIM

Tumor marker based recurrences of previously treated testicular cancer are generally detected with CT scan. They sometimes cannot be visualized with conventional morphologic imaging. FDG-PET has the ability to detect these recurrences. PET probe-guided surgery, may facilitate the extent of surgery and optimize the surgical resection.

METHODS

Three patients with resectable 2nd or 3rd recurrent testicular cancer based on elevated tumor markers after previous various chemotherapy schedules and resections of residual retroperitoneal tumor masses were included in this study. A diagnostic FDG-PET was performed and a hotspot in previously operated area of the retroperitoneal space in all three patients was visualized. PET probe-guided surgery was performed using a high-energy gamma probe 3 h post-injection of 500 MBq FDG.

RESULTS

All patients showed extended adhesions and scar tissue in the retroperitoneal area due to the previous surgeries. Pre-operative PET/CT scan showed a good correlation with intra-operative PET probe-guided detection of recurrent lesions. There was a high target to background ratio (TGB) of 5:1 during the procedure. In one patient, a 2 cm large lesion, which did not show on pre-operative FDG-PET scan, was detected with the PET probe. Histopathologic tissue evaluation demonstrated recurrent vital tumor in all PET probe positive lesions.

CONCLUSIONS

PET probe-guided surgery seems to be a promising tool to localize FDG-PET positive lesion in recurrent testicular cancer in hardly accessible surgical locations. PET probe-guided surgery might be a useful technique in surgical oncology for recurrent testicular cancer and has the potential to be applied in surgery of other malignant diseases.

The clinical advances of fluorine-2-D-deoxyglucose--positron emission tomography/computed tomography in urological cancers

Fluorine-18 labeled fluorine-2-D-deoxyglucose (FDG) is the most frequently used positron emission tomography (PET) probe but it has certain limitations when used in urological cancers. The introduction of co-registered PET and computed tomography (PET/CT) represents a major advance in technology and FDG-PET/CT has now become the new standard. The diagnostic performance of FDG-PET and PET/CT depends on the metabolic activity of tumor tissue, which is generally low in primary renal cell and prostate cancers and often in their metastatic deposits. In contrast, both seminomatous and nonseminomatous germ cell tumors are characterized by upregulated glucose metabolism with subsequently increased FDG uptake in tumor sites. Generally, the metabolic activity provides accurate information regarding the presence of a viable tumor, except in patients with residual mature teratoma. Although bladder cancer demonstrates sufficiently increased FDG uptake, primary tumors are difficult to identify due to the renal excretion of FDG. The accuracy of FDG-PET/CT in metabolically active metastases is generally higher compared to conventional CT except for identifying small lung deposits. With disease progression and subsequent de-differentiation of prostate cancer, castrate resistant disease is more likely to present with lesions that have increased glucose metabolism.

Retroperitoneal lymph node dissection after chemotherapy

Retroperitoneal lymph node dissection after chemotherapy (PC-RPLND) plays a crucial role in managing patients with advanced germ cell tumours (GCTs). In the last few years improvements in radiographic staging, a better understanding of the role of serum tumour markers, and the introduction of cisplatin-based chemotherapy have all contributed to this surgical therapy. PC-RPLND is necessary when residual radiographic abnormalities are present after chemotherapy. The need for a PC-RPLND in the face of normal findings from computed tomography (CT) is controversial. CT criteria alone are not sufficiently reliable to distinguish viable tumour or teratoma from necrosis. No combination of variables can predict negative retroperitoneal pathology with sufficient accuracy after induction chemotherapy. Unresected teratoma or viable GCT are at least partly chemorefractory and, if untreated, will progress. So completeness of resection is an independent and consistent predictive variable of clinical outcome. In PC-RPLND surgical margins should not be compromised in an attempt to preserve ejaculation, although nerve-sparing dissections are possible in patients with marker normalization after chemotherapy and necrotic tissue in frozen-section histology. In these patients nerve-sparing techniques and the reduction of surgical field to the left- or right-sided template are applicable to preserve antegrade ejaculation and consecutive fertility. The size and location of residual masses coupled with the retroperitoneal desmoplastic reaction make PC-RPLND a technically demanding procedure that should be performed by experienced surgeons in dedicated referral centres.

Imaging 'the lost tribe': a review of adolescent cancer imaging. Part 1

Although a small proportion of all cancer registrations, malignancy in adolescence and young adulthood remains the most common natural cause of death in this age group. Advances in the management and outcomes of childhood cancer have not been matched within the adolescent population, with increasing incidence and poorer survival seen amongst teenagers with cancer compared with other populations. There have been increasing moves towards specific adolescent oncology centres, with the aim of centralising expertise, however, ‘adolescent imaging’ does not exist as a speciality in the same way that paediatric imaging does, with responsibility for imaging adolescent patients sometimes falling to paediatric radiologists and sometimes to ‘adult’ radiologists, usually with a specific interest in a tumour type or body system. In this article, imaging of the more common malignancies, encountered in adolescent patients is reviewed. Complications of treatment are reviewed in another article to give an overview of adolescent oncology imaging practice.

[18F]Fluorodeoxyglucose Positron Emission Tomography in Nonseminomatous Germ Cell Tumors After Chemotherapy: The German Multicenter Positron Emission Tomography Study Group

Purpose

In patients with metastatic nonseminomatous germ cell cancer (NSGCT), residual masses after chemotherapy (CTX) can consist of vital carcinoma, mature teratoma, or necrosis. This prospective trial has evaluated the accuracy of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) for the prediction of histology compared with computed tomography (CT) and serum tumor markers (STM).

Patients and Methods

A total of 121 patients with stage IIC or III NSGCT scheduled for secondary resection after cisplatin-based CTX were included. FDG-PET was performed after completion of CTX. All results were confirmed by histopathology and correlated to STM and CT.

Results

Prediction of tumor viability with FDG-PET was correct in 56%, which did not reach the expected clinically relevant level of 70%, and was not better than the accuracy of CT (55%) or STM (56%). Sensitivity and specificity of FDG-PET were 70% and 48%. The positive predictive values were not significantly different (55%, 61%, and 59% for CT, STM, and PET, respectively). Judging only vital carcinoma as a true malignant finding, the negative predictive value increased to 83% for FDG-PET.

Conclusion

The presence of vital carcinoma and mature teratoma is common (55%) in residual masses in patients with NSGCT, and CT and STM cannot reliably predict absence of disease. In contrast to prior studies, this prospective trial, which is the only with histologic confirmation in all patients, demonstrated that FDG-PET is unable to give a clear additional clinical benefit to the standard diagnostic procedures, CT and STM, in the prediction of tumor viability in residual masses.

Normal uptake of 18F-FDG in the testis: an assessment by PET/CT

OBJECTIVE

The aim of this study was to assess the physiological uptake of 18F-fluoro-2-deoxyglucose (FDG) by an apparently normal testis with combined positron emission tomography-computed tomography (PET/CT) and its correlation with age, blood glucose level, and testicular volume.

METHODS

The testicular uptake of 18F-FDG, expressed as the standardized uptake value (SUV), was measured on PET/CT images in 203 men. The correlation between SUV and age, blood glucose level, and testicular volume was assessed.

RESULTS

The SUV in the total of 406 testes was 2.44 +/- 0.45 (range 1.23-3.85). The SUV was 2.81 +/- 0.43 (2.28-3.85) for 30-39 years (n = 12), 2.63 +/- 0.45 (1.77-3.75) for 40-49 years (n = 64), 2.46 +/- 0.35 (1.44-3.15) for 50-59 years (n = 82), 2.51 +/- 0.41 (1.50-3.46) for 60-69 years (n = 86), 2.43 +/- 0.47 (1.42-3.29) for 70-79 years (n = 86), and 2.18 +/- 0.45 (1.23-3.03) for 80-89 years (n = 76). When we calculated the mean SUV of bilateral testes in each patient, there were significant statistical differences between those in the age group of 30-39 years and 80-89 years, 40-49 years and 80-89 years, and 50-60 years and 80-89 years, when using an unpaired test with Bonferroni correction. The laterality index (|L - R|/(L + R) x 2) in 203 men was 0.066 +/- 0.067 (0-0.522). There was a mild correlation between the mean SUV and age (r = -0.284, P < 0.001) as well as between the mean SUV and mean volume (r = +0.368, P < 0.001). There was no correlation between the mean SUV and glucose blood level (r = -0.065, P = 0.358).

CONCLUSIONS

Some uptake of FDG is observed in the normal testis and declines slightly with age. Physiological FDG uptake in the testis should not be confused with pathological accumulation.

18fluorodeoxyglucose positron emission tomography in the prediction of relapse in patients with high-risk, clinical stage I nonseminomatous germ cell tumors: preliminary report of MRC Trial TE22--the NCRI Testis Tumour Clinical Study Group

PURPOSE

There are several management options for patients with clinical stage I (CS1) nonseminomatous germ cell tumors (NSGCT); this study examined whether an 18fluorodeoxyglucose positron emission tomography (18FDG PET) scan could identify patients without occult metastatic disease for whom surveillance is an attractive option.

METHODS

High-risk (lymphovascular invasion positive) patients with CS1 NSGCT underwent 18FDG PET scanning within 8 weeks of orchidectomy or marker normalization. PET-positive patients went off study; PET-negative patients were observed on a surveillance program. The primary outcome measure was the 2-year relapse-free rate (RFR) in patients with a negative PET scan (the negative predictive value). Assuming an RFR of 90% to exclude an RFR less than 80% with approximately 90% power, 100 PET-negative patients were required; 135 scanned patients were anticipated.

RESULTS

Patients were registered between May 2002 and January 2005, when the trial was stopped by the independent data monitoring committee due to an unacceptably high relapse rate in the PET-negative patients. Of 116 registered patients, 111 underwent PET scans, and 88 (79%) were PET-negative (61% of preorchidectomy marker-negative patients v 88% of marker-positive patients; P = .002); 87 proceeded to surveillance, and one requested adjuvant chemotherapy. With a median follow-up of 12 months, 33 of 87 patients on surveillance relapsed (1-year RFR, 63%; 90% CI, 54% to 72%).

CONCLUSION

Though PET identified some patients with disease not detected by computed tomography scan, the relapse rate among PET negative patients remains high. The results show that 18FDG PET scanning is not sufficiently sensitive to identify patients at low risk of relapse in this setting.

Molecular Positron Emission Tomography and PET/CT Imaging in Urological Malignancies

OBJECTIVES

Positron emission tomography (PET) provides unique insights into molecular pathways of diseases. PET using [F-18]-fluorodeoxyglucose (FDG) has gained increasing acceptance for the diagnosis, staging, and treatment monitoring of various tumour types. The aim of this review is to provide an update on the current status of molecular PET and PET/CT imaging in urological malignancies.

METHODS

The current literature on PET and PET/CT imaging was reviewed and summarized for prostate cancer, bladder cancer, renal cell carcinoma, and germ cell tumours.

RESULTS

Depending on the radiotracer used, PET offers diagnostic information based on glucose, choline or amino acid metabolism and has also been applied to imaging tumour cell proliferation and tissue hypoxia in urological malignancies. The diagnostic performance of FDG-PET is hampered by the renal excretion of FDG and by the low metabolic activity often seen in tumours such as prostate cancer. However, new PET tracers including radiolabelled choline and acetate may offer an alternative approach. There is consistent evidence that FDG-PET provides important diagnostic information in detecting metastatic and recurrent germ cell tumours and it might offer additional information in the staging and restaging of bladder and renal cancer.

CONCLUSIONS

Although PET imaging has been shown to be a clinically useful tool, its application in urological malignancies still needs to be fully determined by larger prospective trials. The introduction of novel PET radiopharmaceuticals along with the new technology of PET/CT will likely change the future role of molecular imaging in urological malignancies.

Thoracic Sarcoidosis Mimicking Metastatic Testicular Cancer: Three Case Reports

Recurrence of testicular tumors in young males generally prompts rapid investigation and treatment. We report 3 patients with past histories of treated testicular cancer referred with radiographic evidence suggestive of intrathoracic metastases. In each case chest imaging demonstrated mediastinal/hilar lymphadenopathy. In one case pulmonary nodules were also identified. In all three patients further work-up revealed non-caseating granulomas consistent with sarcoidosis. All patients have since been followed and remain free of testicular cancer. No patient has required therapy for sarcoidosis. Although rare, new intra-thoracic lymphadenopathy in previously treated testicular cancer patients can represent sarcoidosis. Tissue diagnosis is essential when the clinical picture remains unclear.

Imaging of testicular germ cell tumours

In testicular germ cell tumour (GCT), imaging plays a central role in assessment of tumour bulk, sites of metastases, monitoring response to therapy, surgical planning and accurate assessment of disease at relapse. The primary modality used for imaging patients with GCT is computed tomography (CT) but plain film radiography, ultrasound, magnetic resonance imaging (MRI) and positron emission tomography (PET) may all have roles to play. This article reviews the role of imaging of testicular germ cell tumours.

Nuclear Medicine Studies of the Prostate, Testes, and Bladder

During the last decade, there has been a significant advancement in imaging of urologic diseases. Transrectal ultrasound (TRUS), computerized tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and positron emission tomography (PET) are still experiencing new developments in urology. Despite these many technological advances, the initial diagnostic procedure for a patient with suspected prostate cancer (PC) is multiple site blind prostate biopsies. There is a need for a noninvasive metabolic imaging modality to direct the site of biopsy to decrease the sampling error. MRS seems promising but as it is a costly and more time-consuming test, further studies are needed to evaluate its clinical utility. Currently, PET does not play any role to direct biopsy. Acetate and choline appear to be better tracers than FDG for the detection of a prostate lesion, however, further well-organized studies are needed before any of these agents can be used clinically. Incidental detection of intense focal uptake in the prostate during whole body PET scanning should be evaluated with prostate-specific antigen (PSA) and TRUS-guided biopsy. Although FDG is inferior to other tracers for primary staging, it may be useful in selected patients with suspected high-grade cancer. The role of ProstaScint scan is still controversial for detection of recurrent PC. This study may be helpful for evaluating nodal metastases when PSA is elevated and bone scan is negative. Bone scan remains the study of choice when bone metastases are suspected (PSA>15-20 ng/mL+/-bone pain). Acetate and choline provide better accuracy than FDG in the detection of local soft tissue disease, nodal involvement, and distant metastases. High FDG uptake may be indicative of more aggressive and possibly androgen-independent disease. PET/CT with any of the above PET tracers will most likely be preferred to the PET scan alone due to better localization of a hot lesion in PET/CT. Nuclear medicine studies also have been used to evaluate acute scrotum and testicular neoplasms. Scrotal scintigraphy has lost its popularity to Doppler ultrasound in the evaluation of the acute scrotum. In testicular tumors, FDG-PET appears to be superior to conventional imaging modalities in initial staging, detection of residual/recurrence, and monitoring treatment response. Tumor markers after treatment occasionally are elevated and cannot locate the site of recurrence, FDG-PET can play a very important role in this regard. Nuclear medicine studies also have been used to evaluate diseases of the urinary bladder. Radionuclide cystography is more sensitive and has less than 1/20 the radiation exposure of the conventional contrast enhanced micturating cystourethrogram (MCU). However, the utility of FDG-PET in the evaluation of bladder cancer seems to be limited to the evaluation of distant metastases. 11C-Methionine and choline may be a better option for local and nodal disease due to their negligible excretion in the urine.

Positron emission tomography in uro-oncology

Positron emission tomography (PET) in uro-oncology has been one of the slowest areas to develop. There are problems because of the excretion of tracer through the renal tract. Its use in prostate cancer has generally being disappointing, with PET being unable to differentiate malignancy from benign prostatic hypertrophy. In more advanced disease and in the search for the site of recurrence, PET can be of more use. Also, new tracers may prove to be more effective. PET has been shown to be of value in testicular cancer, particularly in defining recurrent disease in residual masses and in patients with raised markers. There is a clear place for PET in some of these cases. Early studies at staging are promising but more work is required to define its exact place. In renal and bladder cancer, PET may be a useful adjunct to conventional imaging in difficult cases and may assist in local staging. In all tumours it is valuable to differentiate fibrosis from recurrent disease in the treatment bed, an area of difficulty for CT/MR.

Diagnostic Value of Tumour Marker Regression Models in Stage 1 Marker-Positive Testicular Cancer

The decay pattern and half-life period evaluation of serum tumour markers are useful parameters in the management of testicular cancer in clinic stage 1. Alpha-fetoprotein and human chorionic gonadotropin serum levels measured after orchiectomy can be used to predict the tumour stage. However, the optimal strategy for marker analysis after orchiectomy has not yet been defined. In this article we describe a graphic interactive method which uses tumour marker clearance to help identify patients with occult metastases after orchiectomy.

PET in the management of urologic malignancies

FDG-PET has a limited role in diagnosis of prostate cancer mainly because of the low uptake of FDG in the tumor and normal excretion of FDG through urine. FDG-PET has shown some promise in the assessment of lymph nodes and bone metastases. There is a large degree of variability when FDG-PET is compared with bone scintigraphy. New C11-labeled radiotracers (acetate, choline, and methionine) have shown promising initial results but further studies are required to determine their role in such settings. These radiotracers provide a unique opportunity for dynamic, multitracer, and quantitative studies, which improve the sensitivity and specificity on PET in this population. Short half-lives and of C-11, however with the limits to their use requires an on-site cyclotron. Recent synthesis schemes with [18F]-labeling, however, may overcome this limitation. FDG-PET has a significant potential to assist with the diagnosis and management of testicular cancer. PET has been most useful in defining the presence or absence of disease in patients with residual masses. PET has shown promising results for the initial diagnosis of this cancer, but further for studies ar required to determine its role in the management of this malignancy. PET can be used in conjunction with conventional imaging techniques to diagnose retroperitoneal masses in patients with primary testicular cancer. FDG-PET has shown very encouraging results in a limited number of studies, and has also demonstrated a good sensitivity for initial staging. FDG-PET seems to be superior to conventional imaging modalities for detecting local disease and recurrence, and distant metastases.

Positronenemissionstomographie (PET) zur Diagnostik und zum Therapiemonitoring bei urologischen Tumoren

Positron emission tomography (PET) using ((18)F)2-fluoro-D-2-desoxyglucose (FDG) has been shown to be a highly sensitive and specific imaging modality in the diagnosis of primary and recurrent tumors and in the control of therapies in numerous non-urologic cancers. It was the aim of this review to validate the significance of PET as a diagnostic tool in malignant tumors of the urogenital tract. A systematic review of the current literature concerning the role of PET for malignant tumors of the kidney, testicles, prostate, and bladder was carried out. The role of FDG PET for renal cell cancer can be seen in the detection of recurrences after definitive local therapy and metastases. The higher sensitivity of PET in comparison to other therapeutic modalities (CT, ultrasound, MRI) in recurrent and metastatic renal cell cancer suggests a supplemental role of this diagnostic procedure to complement other imaging modalities.The clinical value of PET is established for the identification of vital tumor tissue after chemotherapy of seminomatous germ cell tumors. This diagnostic method has little significance for primary tumor staging and diagnosis of non-seminomatous germ cell tumor because of the high probability of false-negative results in adult teratomas. FDG PET is not sensitive enough in the diagnosis of primary or recurrent tumors in prostate or bladder cancer. Also PET did not prove to be superior to conventional bone scintigram in the detection of mostly osteoblastic metastases in prostate cancer. The recent use of alternative tracers, which are partly not eliminated by urinary secretion (acetate, choline) has increased the sensitivity and specificity of PET also in this tumor entity so that further clinical investigations are needed to validate these technical modifications in their significance for this imaging modality. PET appears to be sufficiently evaluated only for the diagnostic follow-up of patients with seminomatous germ cell tumors after chemotherapy to regard it is the diagnostic tool of first choice. For all other tumors of the urogenital tract this proof is still awaited.

The reproductive tract

Diagnostic imaging has played a major role in the evaluation of patients with the cancers of the reproductive tract. The imaging modalities have included ultrasonography, computed tomography, magnetic resonance imaging, hysterosalpingography, and scintigraphy with radiolabeled monoclonal antibodies. Positron emission tomography (PET) with [F-18]fluorodeoxyglucose also has been shown to be useful in the imaging evaluation of these patients. Clinical applications have included initial staging and posttherapy restaging of disease, detecting metastatic disease, differentiating posttherapy anatomic alterations from recurrent or residual disease, and predicting and evaluating treatment response. In this article, we review the diagnostic utility of dedicated PET and combined PET-computed tomography systems in the imaging assessment of reproductive tract malignancies (excluding prostate cancer) in both sexes with an emphasis on fluorodeoxyglucose applications.

European consensus on diagnosis and treatment of germ cell cancer: a report of the European Germ Cell Cancer Consensus Group (EGCCCG)

Germ cell tumour is the most frequent malignant tumour type in young men with a 100% rise in the incidence every 20 years. Despite this, the high sensitivity of germ cell tumours to platinum-based chemotherapy, together with radiation and surgical measures, leads to the high cure rate of > or = 99% in early stages and 90%, 75-80% and 50% in advanced disease with 'good', 'intermediate' and 'poor' prognostic criteria (IGCCCG classification), respectively. The high cure rate in patients with limited metastatic disease allows the reduction of overall treatment load, and therefore less acute and long-term toxicity, e.g. organ sparing surgery for specific cases, reduced dose and treatment volume of irradiation or substitution of node dissection by surveillance or adjuvant chemotherapy according to the presence or absence of vascular invasion. Thus, different treatment options according to prognostic factors including histology, stage and patient factors and possibilities of the treating centre as well may be used to define the treatment strategy which is definitively chosen for an individual patient. However, this strategy of reduction of treatment load as well as the treatment itself require very high expertise of the treating physician with careful management and follow-up and thorough cooperation by the patient as well to maintain the high rate for cure. Treatment decisions must be based on the available evidence which has been the basis for this consensus guideline delivering a clear proposal for diagnostic and treatment measures in each stage of gonadal and extragonadal germ cell tumour and individual clinical situations. Since this guideline is based on the highest evidence level available today, a deviation from these proposals should be a rare and justified exception.