Elsevier

Urology

Volume 54, Issue 5, November 1999, Pages 900-904
Urology

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

https://doi.org/10.1016/S0090-4295(99)00272-1Get rights and content

Abstract

Objectives. To compare positron emission tomography (PET) using 18-fluoro-2-deoxyglucose (FDG) with conventional clinical staging in unselected patients with germ cell cancer.

Methods. Fifty patients underwent PET scans of the abdomen (n = 50) and chest (n = 41) after the initial diagnosis. PET images were evaluated qualitatively and quantitatively using standardized uptake values (SUVs). The results were compared with computed tomography (CT) results and tumor markers (human chorionic gonadotropin, alpha-fetoprotein, and lactate dehydrogenase). Retroperitoneal lymphadenectomy in 12 patients and clinical staging, including follow-up data in all patients, were taken as a reference standard.

Results. PET detected metastases in 13 (87%) of 15 patients and excluded metastases in 33 (94%) of 35 patients. A sensitivity of 73% and a specificity of 94% were obtained using CT. The respective values for tumor marker determination were 67% and 100%. Retroperitoneal metastases were detected in 2 patients by PET only and in 1 patient by CT only. In the latter patient, surgery of a residual mass after chemotherapy revealed a well-differentiated teratoma. False-negative findings with PET and CT occurred in 2 patients with retroperitoneal metastases approximately 10 mm in size. False-positive findings were due to sarcoidosis or to muscular activity of the neck. Quantitative FDG uptake was very heterogeneous, with an SUV ranging from 1.8 to 17.3.

Conclusions. FDG PET has the potential to improve clinical staging of testicular cancer. However, PET, as well as CT, is limited in the detection of small retroperitoneal lymph node metastases.

Section snippets

Patients

Fifty patients with germ cell cancer underwent PET imaging in addition to routine staging after the initial diagnosis. The study was approved by the local ethical committee, and the patients were informed in detail about the PET examination. The median age of all patients was 31 years (range 20 to 76). The histopathologic diagnosis after orchiectomy was pure seminoma in 30 patients, embryonal carcinoma in 7, teratocarcinoma in 5, mixed tumor in 5, and teratoma in 2 patients. Unclassified germ

Results

Metastatic spread was finally suspected in 14 (28%) of 50 patients. It was more common in nonseminomatous (10 of 19 patients) than in seminomatous (4 of 30 patients) tumors. In the patient with unclassified retroperitoneal germ cell tumor, no additional lesions were present. Table I shows the performance of all three diagnostic modalities for detection of malignant lesions. The differences were not statistically significant using Fisher’s exact test.

In comparison to the final clinical staging,

Comment

The use of FDG PET in patients with testicular cancer has been reported by several investigators.9, 11, 12, 13, 14, 15 Although the clinical usefulness of FDG PET was demonstrated in re-evaluation after chemotherapy,9, 12 its value for initial staging has only recently been studied in detail.15 In contrast to the study by Müller-Mattheis et al.,15 in the present study, “whole-body” PET was performed that encompassed the abdomen and chest in most of the patients. Comparison with CT may be

Conclusions

FDG PET has the potential to improve clinical staging of testicular cancer. However, PET, as well as CT, is limited in the detection of small retroperitoneal lymph node metastases. Larger trials are needed to draw a final conclusion about the usefulness of FDG PET imaging as a routine method for staging testicular cancer. Such a trial is now being performed in Germany.23

Acknowledgements

To the technicians of our PET group for their skilled work and to A. Rodón for editorial assistance.

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