Retroperitoneal metastases in testicular cancer: role of CT measurements of residual masses in decision making for resection after chemotherapy

Serum Levels of MicroRNA-371a-3p for Predicting the Histology of Postchemotherapy Residual Masses of Germ Cell Tumours

BACKGROUND AND OBJECTIVE

Serum levels of microRNA-371a-3p (M371) represent a novel and sensitive biomarker of germ cell tumours (GCTs). This study analysed the utility of M371 to identify viable cancer (VC) in postchemotherapy (pc) residual masses with the underlying goal of avoiding overtreatment.

METHODS

A multicentric, prospective diagnostic study was conducted in 180 GCT patients undergoing pc resection of residual masses. A correlation of M371 measurement results with the histological presence of VC in masses was found. A receiver operating characteristic analysis was performed for exploring the performance characteristics of the test.

KEY FINDINGS AND LIMITATIONS

The sensitivity was found to be 68.9%, specificity 99.3%, area under the curve 0.813, positive predictive value 0.969, and negative predictive value 0.905; sensitivity is significantly associated with the percentage of VC in the mass. In specimens with ≤10% VC, there were 33.3% elevated M371 levels as opposed to 85.7% in specimens with >50% VC. Teratoma and somatic-type malignancy do not express M371. A lack of a central pathological review is a limitation.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The M371 test can identify 68.9% of patients with VC in pc masses. However, cases with <10% VC in the mass may escape detection. Teratoma does not express M371. The test alone cannot correctly identify patients requiring pc surgery, but it may be a tool for scheduling the extent of surgery.

PATIENT SUMMARY

The microRNA-371a-3p (M371) test can identify about two-thirds of patients with viable cancer in residual metastatic masses following chemotherapy for germ cell tumours. Only masses with high percentages of viable cancer cells can be identified, and the histological subtype teratoma remains undetected with the test.

A meta-analysis of clinicopathologic features that predict necrosis or fibrosis at post-chemotherapy retroperitoneal lymph node dissection in individuals receiving treatment for non-seminoma germ cell tumours

Purpose

Post-chemotherapy retroperitoneal lymph node dissection (pcRPLND) for residual nodal masses is a critical component of care in metastatic testicular germ cell tumour (GCT). However, the procedure is not of therapeutic value in up to 50% of individuals in whom histopathology demonstrates post-treatment necrosis or fibrosis alone. Improved diagnostic tools and clinicopathologic features are needed to separate individuals who benefit from pcRPLND and avoid surgery in those who do not.

Methods

A prospectively registered meta-analysis of studies reporting clinicopathologic features associated with teratoma, GCT and/or necrosis/fibrosis at pcRPLND for metastatic non-seminoma GCT (NSGCT) was undertaken. We examined the effect of various clinicopathologic factors on the finding of necrosis/fibrosis at pcRPLND. The log odds ratios (ORs) of each association were pooled using random-effects models.

Results

Using the initial search strategy, 4,178 potentially eligible abstracts were identified. We included studies providing OR relating to clinicopathologic factors predicting pcRPLND histopathology, or where individual patient-level data were available to permit the calculation of OR. A total of 31 studies evaluating pcRPLND histopathology in 3,390 patients were eligible for inclusion, including two identified through hand-searching the reference lists of eligible studies. The following were associated with the presence of necrosis/fibrosis at pcRPLND: absence of teratomatous elements in orchidectomy (OR 3.45, 95% confidence interval [CI] 2.94-4.17); presence of seminomatous elements at orchidectomy (OR 2.71, 95% CI 1.37-5.37); normal pre-chemotherapy serum bHCG (OR 1.96, 95% CI 1.62-2.36); normal AFP (OR 3.22, 95% CI 2.49–4.15); elevated LDH (OR 1.72, 95% CI 1.37-2.17); >50% change in mass during chemotherapy (OR 4.84, 95% CI 3.94-5.94); and smaller residual mass size (<2 cm versus >2 cm: OR 3.93, 95% CI 3.23-4.77; <5 cm versus >5 cm: OR 4.13, 95% CI 3.26-5.23).

Conclusions

In this meta-analysis, clinicopathologic features helped predict the presence of pcRPLND necrosis/fibrosis. Collaboration between centres that provide individual patient-level data is required to develop and validate clinical models and inform routine care to direct pcRPLND to individuals most likely to derive benefits.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021279699

The combination of microRNA-371a-3p and 375-5p can distinguish viable germ cell tumor and teratoma from necrosis in postchemotherapy retroperitoneal lymph node dissection specimens

Background

To identify a combination of microRNAs (miRNA) to differentiate between viable tumor (V) or teratoma (T) and necrosis/fibrosis (N) in pcRPLND specimens of metastatic germ cell tumor (GCT) patients with residual masses ≥1 cm after chemotherapy. Biomarker guided therapy could reduce overtreatment with pcRPLND in patients with only N.

Methods

We selected 48 metastatic GCT patients who had undergone pcRPLND. V, pure T and N was shown in the resected tissue of 16 patients, respectively. Of these areas total RNA was isolated and miRNA expression was analyzed for miR-371a-3p, 375-3p, and 375-5p using qPCR. ROC analysis was performed for each miRNA and for all combinations in order to determine the discriminatory capacity of V and T vs. N.

Results

On comparing V vs. N miR-371a-3p achieved the highest fold change (FC) of 31.1 (P=0.023) while for T vs. N miR-375-5p performed best (FC 64.2; P<0.001). Likewise, the most accurate AUC for V was 0.75 using miR-371a-3p, for T 0.80 using miR-375-5p. Combining the best performing miRNAs for V and T resulted in an AUC of 0.94 with a sensitivity of 93.75, specificity of 93.75, PPV of 96.8 and NPV of 83.3.

Conclusions

By combining miR-371a-3p and miR-375-5p in pcRPLND tissue samples V and T could be distinguished from necrosis/fibrosis with great accuracy. This combination of miRNAs might serve as new biomarker in the future, in order to spare miRNA-negative patients from pcRPLND. However, further studies analyzing patient’s serum are needed to confirm the clinical impact of these biomarkers.

Factores asociados a la histología de masa residual retroperitoneal post quimioterapia en tumor testicular de células germinales

Objetivo El objetivo de este estudio es describir las características y factores relacionados con la histología de la masa residual postquimioterapia en pacientes con tumor de células germinales de origen testicular sometidos a linfadenectomía retroperitoneal durante 12 años de seguimiento.

Métodos Retrospectivamente se recolectaron datos clínicos, quirúrgicos y patológicos de la historia clínica de los pacientes en un centro de referencia de manejo de cáncer durante un periodo de 12 años. Se estimó la asociación entre los datos recolectados con la histología del tumor residual post quimioterapia.

Resultados Se incluyeron 64 pacientes, la edad promedio fue 28.1 años, el tamaño promedio de masa residual fue de 6.7 cm. La histología de la masa residual fue teratoma en 60.9%, necrosis 26.5% y tumor viable 12.5%. El grupo pronóstico tiene asociación con la histología de la masa retroperitoneal. Las masas con histología de necrosis tuvieron menor tamaño con media 6.5 cm mientras que otras histologías tuvieron tamaño promedio de la masa residual de 10.4 cm.

Conclusiones La LNDRP-PC es el estándar de tratamiento en masas residuales retroperitoneales después de quimioterapia y puede generar sobre-tratamiento hasta en 50% de los casos. El teratoma en la histología testicular está relacionado mayor tamaño de la masa residual retroperitoneal. Las características histológicas de la masa residual son comparables con otras series.

Serum miRNA Predicts Viable Disease after Chemotherapy in Patients with Testicular Nonseminoma Germ Cell Tumor

PURPOSE

Retroperitoneal lymph node dissection is recommended for residual masses greater than 1 cm after chemotherapy of nonseminomatous germ cell tumors. Currently there is no reliable predictor of post-chemotherapy retroperitoneal lymph node dissection histology. Up to 50% of patients harbor necrosis/fibrosis only so that a potentially morbid surgery has limited therapeutic value. In this study we evaluated the ability of defined serum miRNAs to predict residual viable nonseminomatous germ cell tumors after chemotherapy.

MATERIALS AND METHODS

Levels of serum miRNA, including miR-371a-3p, miR-373-3p and miR-367-3p, were measured using the ampTSmiR (amplification targeted serum miRNA) test in 82 patients, including 39 in cohort 1 and 43 in cohort 2, who were treated with orchiectomy, chemotherapy and post-chemotherapy retroperitoneal lymph node dissection. miRNA levels were compared to clinical characteristics and serum tumor markers, and correlated with the presence of viable germ cell tumor vs fibrosis/necrosis and teratoma. ROC analysis was done to determine miRNA discriminative capacity.

RESULTS

miRNA levels were significantly associated with disease extent at chemotherapy and they decreased significantly after chemotherapy. Conventional serum tumor marker levels were uninformative after chemotherapy. However, after chemotherapy miRNA levels remained elevated in patients harboring viable germ cell tumor in post-chemotherapy retroperitoneal lymph node dissection specimens. miR-371a-3p demonstrated the highest discriminative capacity for viable germ cell tumors (AUC 0.874, 95% CI 0.774-0.974, p <0.0001). Using an adapted hypothetical cutoff of 3 cm or less for surgical intervention miR-371a-3p correctly stratified all patients with viable residual retroperitoneal germ cell tumors with 100% sensitivity (p = 0.02).

CONCLUSIONS

Our study demonstrates for the first time the potential value of miR-371a-3p to predict viable germ cell tumors in residual masses after chemotherapy. Prospective studies are required to confirm clinical usefulness.

Postchemotherapy Retroperitoneal Lymph Node Dissection in Patients With Nonseminomatous Testicular Cancer: A Single Center Experiences

BACKGROUND

Testicular cancer accounts for about 1 - 1.5% of all malignancies in men. Radical orchiectomy is curative in 75% of patients with stage I disease, but advance stage with retroperitoneal lymph node involvement needs chemotherapy. All patients who have residual masses ≥ 1 cm after chemotherapy should undergo postchemotherapy retroperitoneal lymph node dissection (PC-RPLND).

OBJECTIVES

Treatment of advanced nonseminomatous testicular cancer is usually a combination of chemotherapy and surgery. We described our experience about postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) in our center.

PATIENTS AND METHODS

In a retrospective cross-sectional study between 2006 and 2011, patients with a history of postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) in Imam Khomeini hospital were evaluated. All patients had normal postchemotherapy serum tumor markers and primary nonseminomatous cancer. We reviewed retrospectively clinical, pathological, and surgical parameters associated with PC-RPLND in our center.

RESULTS

Twenty-one patients underwent bilateral PC-RPLND. Mean age was 26.3 years (ranged 16 - 47). Mean size of retroperitoneal mass after chemotherapy was 7.6 cm. Mean operative time was 198 minutes (120 - 246 minutes). Mean follow-up time was 38.6 months. Pathologic review showed presence of fibrosis/necrosis, viable germ cell tumor and teratoma in 8 (38.1%), 10 (47.6%) and 3 (14.28%) patients, respectively. One patient in postoperative period of surgery and three patients in two first years after surgery were expired. Of 17 alive patients, only two (11.8%) had not retrograde ejaculation.

CONCLUSIONS

PC-RPLND is one the major operations in the field of urology, which is associated with significant adjunctive surgeries. In appropriate cases, PC-RPLND was associated with good cancer specific survival in tertiary oncology center.

Contemporary management of postchemotherapy testis cancer

CONTEXT

Some controversy still exists regarding the management of testis cancer following chemotherapy for disseminated disease.

OBJECTIVE

To review the available literature concerning the management of postchemotherapy testis cancer.

EVIDENCE ACQUISITION

A Medline search was conducted to identify original and review articles, as well as guidelines addressing the management of testis cancer following first-line chemotherapy. Keywords included germ cell tumor, testis cancer, retroperitoneal lymph node dissection, and chemotherapy. The most relevant articles were critically reviewed with the consensus of all the collaborative authors, who have expertise in the management of germ cell tumors (GCTs).

EVIDENCE SYNTHESIS

Approximately one-third of patients who undergo chemotherapy for metastatic GCTs have residual retroperitoneal disease. All patients with residual masses ≥1cm after chemotherapy for nonseminomatous GCTs should undergo postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) because of the risk of mature teratoma in 40-45% of cases and of viable GCT in 10-15% of cases. Patients who obtain a complete serologic remission and radiographic residual <1 cm after chemotherapy have a 6-9% risk of relapse. Patients with a completely resected teratoma in only the PC-RPLND specimen have a >90% chance of cure, while patients with viable GCTs should be considered for additional therapy, depending on the percentage of viable tumor. In patients with disseminated seminoma, postchemotherapy masses <3cm may be safely observed, while patients with masses >3 cm should be evaluated with positron emission tomography (PET)/computed tomography 2 mo after completion of chemotherapy, with very selective administration of PC-RPLND. Late relapse occurring >2 yr after chemotherapy is rare, and surgery remains the mainstay of therapy in cases of resectable masses independent of tumor markers. There is still controversy on whether high-dose chemotherapy confers a survival benefit compared with conventional-dose chemotherapy in the salvage setting. Surgery should always be considered for resectable masses following salvage therapies or in chemoresistant disease to maximize chance of cure.

CONCLUSIONS

Patients with advanced GCTs can achieve long-term disease-free survival when chemotherapy is combined with expert and judicious resection of residual disease. PC-RPLND is recommended for residual masses >1cm identified on postchemotherapy imaging in nonseminomatous GCT and possibly for PET-positive residual disease ≥3cm in treated seminomas.

Management of residual mass in nonseminomatous germ cell tumors following chemotherapy

Advanced stage nonseminomatous testis cancer is commonly treated with chemotherapy and surgical resection. Patients with retroperitoneal residual masses >1cm following induction chemotherapy with normalized tumor markers should undergo a post-chemotherapy retroperitoneal lymph node dissection. Post chemotherapy retroperitoneal residual mass less than 1 cm with normal markers may be considered as complete response, although the possibility of residual teratoma and viable germ cell tumor are not definitively ruled out. Excellent long term disease free survival following surveillance may justify this option as the treatment of choice in this cohort of patients.

American Society of Clinical Oncology Clinical Practice Guideline on Uses of Serum Tumor Markers in Adult Males With Germ Cell Tumors

Purpose

To provide recommendations on appropriate uses for serum markers of germ cell tumors (GCTs).

Methods

Searches of MEDLINE and EMBASE identified relevant studies published in English. Primary outcomes included marker accuracy to predict the impact of decisions on outcomes. Secondary outcomes included proportions of patients with elevated markers and statistical tests of elevations as prognostic factors. An expert panel developed consensus guidelines based on data from 82 reports.

Results

No studies directly compared outcomes of decisions with versus without marker assays. The search identified few prospective studies and no randomized controlled trials; most were retrospective series. Lacking data on primary outcomes, most Panel recommendations are based on secondary outcomes (relapse rates and time to relapse).

Recommendations

The Panel recommended against using markers to screen for GCTs, to decide whether orchiectomy is indicated, or to select treatment for patients with cancer of unknown primary. To stage patients with testicular nonseminomas, the Panel recommended measuring three markers (α-fetoprotein [AFP], human chorionic gonadotropin [hCG], and lactate dehydrogenase [LDH]) before and after orchiectomy and before chemotherapy for those with extragonadal nonseminomas. They also recommended measuring AFP and hCG shortly before retroperitoneal lymph node dissection and at the start of each chemotherapy cycle for nonseminoma, and periodically to monitor for relapse. The Panel recommended measuring postorchiectomy hCG and LDH for patients with seminoma and preorchiectomy elevations. They recommended against using markers to guide or monitor treatment for seminoma or to detect relapse in those treated for stage I. However, they recommended measuring hCG and AFP to monitor for relapse in patients treated for advanced seminoma.

[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.

Diagnostic performance of three-dimensional ultrasound extended imaging at scrotal mass lesions

OBJECTIVES

High resolution two-dimensional ultrasound (2D US) difficulty in evaluation of some scrotal mass lesions is not frequent. The aim of the present study was to prospectively evaluate the diagnostic performance of three-dimensional ultrasound extended imaging (3D XI) in characterization of those lesions.

METHODS

The study protocol had the approval of the University's review board all participants' informed consents were obtained. The study included 28 selected patients (12 testicular and 16 para-testicular mass lesions) examined by 2D US and 3D XI applications including computed multi-slice view (MSV) and multi-resolution enhanced images (XI MR). Results were correlated with histopathological findings.

RESULTS

Two-dimensional ultrasound did not adequately characterize 28 patients out of 329 (8.5%). 3D XI interrogation was an easy procedure and distinctive of the pathological findings in 27 patients out of 28 (96.4%). The performance of XI MR with respect to characterization provided additional diagnostic information over MSV.

CONCLUSIONS

The performance of 3D XI with respect to testicular mass characterization proved better than static 2D US. Subsequently, the results of this study suggest that the routine use of 2D US in diagnosis of scrotal mass lesions should preferably be upgraded to 3D XI methods.

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.

18F-fluorodeoxyglucose positron emission tomography in evaluation of germ cell tumor after chemotherapy

OBJECTIVES

To evaluate the role of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) in the assessment of germ cell tumors after chemotherapy.

METHODS

We reviewed patients' records for the histologic findings and clinical outcome. 18F-FDG PET results were correlated with tissue histologic features where available; and if not available, the correlation was with the clinical outcome.

RESULTS

A total of 45 PET studies were performed on 38 patients (age range 19 to 64 years, median 31). All patients had received chemotherapy. In the nonseminomatous germ cell tumor (NSGCT) group, of the 31 patients with one scan, 18 PET scans were reported as positive, with only 2 not having active disease. Of the 12 negative scans, 6 showed teratoma, 1 tumor, and 5 did not show active disease. The equivocal scan revealed thyroid adenoma. In the seminoma group, the PET scans correlated well with the clinical and histologic outcomes. Four patients underwent salvage chemotherapy, and in this subgroup, the PET findings also correlated with the outcome.

CONCLUSIONS

(18)F-FDG PET is a promising tool as an adjunct to current imaging techniques in detecting residual viable germ cell tumor after chemotherapy. In NSGCT, a positive PET scan was accurate in 16 of 18 patients, although negative PET studies did not exclude the presence of disease, mainly because of the presence of teratoma. In seminoma, a negative 18F-FDG PET study correlated with a favorable clinical outcome. PET was also predictive of the response to salvage chemotherapy and was highly specific for active tumor in both NSGCT and seminoma.

Postchemotherapy retroperitoneal surgery remains necessary in patients with nonseminomatous testicular cancer and minimal residual tumor masses

PURPOSE

To determine preoperative parameters that predict the histology of specimens obtained by retroperitoneal lymph node dissection (RPLND) in patients with nonseminomatous germ cell cancer (NSGCT) whose residual mass was </= 20 mm in diameter after modern cisplatin-based induction chemotherapy.

PATIENTS AND METHODS

Eighty-seven patients with metastatic NSGCT underwent RPLND after having received cisplatin- or carboplatin-based induction chemotherapy. In all patients, the largest diameter of the residual mass on the transaxial plane was </= 20 mm, as assessed by abdominal computed tomography (CT) immediately before RPLND.

RESULTS

Complete fibrosis or necrosis was found in 58 patients (67%), teratoma was found in 23 patients (26%), and vital malignant germ cell tumor was found in six patients (7%), including one patient with rhabdomyosarcoma in the RPLND specimen. In five of the six latter patients, the residual lesion was </= 10 mm at pre-RPLND CT. No pre- or postchemotherapy clinical or radiologic parameter was identified that significantly predicted the histology of the residual mass.

CONCLUSION

One third of retroperitoneal postchemotherapy lesions </= 20 mm contained residual vital tumor tissue, despite modern chemotherapy regimens. Therefore, postchemotherapy RPLND remains necessary in patients with minimal-size residual lesions to facilitate easy and safe follow-up and initiate additional therapy as early as possible, thus avoiding recurrences.

A new prognostic model for testicular germ cell tumours

In univariate analyses of patients with metastatic testicular germ cell tumours (TGCT), both the International Germ Cell Consensus Classification (IGCCC) and serum lactate dehydrogenase (S-LD) isoenzyme 1 catalytic concentration (S-LD-1) significantly predicted survival. In complementary analyses of 81 patients with metastatic TGCT, S-LD and S-LD-1 classified the prognosis differently for 23 patients. In multivariate Cox hazard analyses of risk factors, only IGCCC and S-LD-1 predicted the prognosis (p=0.036, and p=0.0007, respectively). A new prognostic model based on prognostic information from main histology, IGCCC, and S-LD-1 changed the prognostic prediction by IGCCC for 19 patients (24%). Judged by to the area under the curve for receiver operation characteristics curves, the new model predicted five-years survival for the patients better than IGCCC and a modified version of the third edition of the TNM classification (p=0.025, and p=0.01, respectively). However, new studies should validate the new model before it is recommended as a general classification system of patients with metastatic TGCT.

Prospective comparison of [18F]fluorodeoxyglucose positron emission tomography with conventional assessment by computed tomography scans and serum tumor markers for the evaluation of residual masses in patients with nonseminomatous germ cell carcinoma

BACKGROUND

To assess the ability of [(18)F]fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) to predict the viability of residual masses after chemotherapy in patients with metastatic nonseminomatous germ cell tumors (GCT), PET results were compared in a blinded analysis with computed tomography (CT) scans and serum tumor marker changes (TUM) as established methods of assessment.

METHODS

Independent reviewers who were blinded to each other's results evaluated the PET results and corresponding CT scan and TUM results in 85 residual lesions from 45 patients. All patients were treated within prospective clinical trials and received primary/salvage, high-dose chemotherapy with autologous blood stem cell support for primary poor prognosis disease or recurrent disease. PET results were assessed both visually and by quantifying glucose uptake (standardized uptake values). Results were validated either by histologic examination of a resected mass and/or biopsy (n = 28 lesions) or by a 6-month clinical follow-up after evaluation (n = 57 lesions).

RESULTS

F-18 FDG PET showed increased tracer uptake in 32 of 85 residual lesions, with 29 true positive (TP) lesions and three false positive (FP) lesions. Fifty-three lesions were classified by PET as negative (no viable GCT), 33 lesions were classified by PET as true negative (TN), and 20 lesions were classified by PET as false negative (FN). In the blinded reading of the corresponding CT scan and TUM results, 38 residual lesions were assessed correctly as containing viable carcinoma and/or teratoma. Forty-six lesions were classified as non-suspicious by CT scan/TUM (33 TN lesions and 14 falsely classified lesions). PET correctly predicted the presence of viable carcinoma in 5 of these 14 and the absence of viable carcinoma in 3 of these 14 lesions. Resulting sensitivities and specificities for the prediction of residual mass viability were as follows: PET, 59% sensitivity and 92% specificity; radiologic monitoring, 55% sensitivity and 86% specificity; and TUM, 42% sensitivity and 100% specificity. The positive and negative predictive values for PET were 91% and 62%, respectively. The diagnostic efficacy of PET did not improve when patients with teratomatous elements in the primary tumor were excluded from the analysis. In patients with multiple residual masses, a uniformly increased residual F-18 FDG uptake in all lesions was a strong predictor for the presence of viable carcinoma.

CONCLUSIONS

F-18 FDG PET imaging performed in conjunction with conventional staging methods offers additional information for the prediction of residual mass histology in patients with nonseminomatous GCT. A positive PET is highly predictive for the presence of viable carcinoma. Other useful indications for a PET examination include patients with multiple residual masses and patients with marker negative disease.