Background:

In recent decades, post-chemotherapy management of seminoma has advanced due to the increased use of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET). Said method alone or combined with computed tomography (CT) has been proposed as a noninvasive tool for evaluating disease extension. Our aim was to determine its utility in describing tumor viability in the post-chemotherapy management of retroperitoneal residual seminomatous masses.

Materials and methods:

A retrospective single-center study was conducted. The clinical case records of 53 patients seen within the time frame of 2013-2018 were reviewed. Treatment response was defined by the Recist 1.1 criteria (for CT) and tumor viability through the SUVmax (in 18F-FDG-PET). According to the results, the patients were divided into groups: surveillance, rescue surgery, radiotherapy, and chemotherapy. The PET/CT result was correlated with the histopathologic study (gold standard) in the surgery group (n=17). In the statistical analysis, sensitivity (S), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) were calculated through the area under the receiver operating characteristics (AUROC) curve. The SPSS v24 software was utilized.

Results:

The analysis, with no group discrimination, produced an ROC curve with a cutoff point of 3.150, S 50%, and Sp 60%, values that are neither discriminatory nor useful for defining tumor viability. The rescue surgery group analysis produced S 100%, Sp 25%, PPV 35%, and NPV 100%.

Conclusions:

In this first Mexican study, 18F-FDG-PET/CT demonstrated very poor utility for determining tumor viability in post-chemotherapy residual seminomatous masses.