Utility of 18F-FDG PET/CT in determining tumor viability in post-chemotherapy management of residual seminomatous masses

Abstract

Background: Post-chemotherapy management of seminoma has evolved in recent decades due to the increasing use of positron emission tomography with 18 fluoro-deoxy-D-glucose (18-FDG-PET) this method alone or combined with computed tomography (CT). It has been proposed as a non-invasive tool to assess the extent of the disease. The objective was to determine its usefulness to determine tumor viability in the management of residual retroperitoneal masses of post-chemotherapy seminoma.

Material and Methods: Monocentric retrospective study, clinical records of 53 patients were reviewed during 2013-2018. Response to treatment was defined by Recist 1.1 criteria by CT and tumor viability by Suv Max by 18-FDG-PET / CT. According to the results, it was divided into groups: surveillance (group 1), rescue surgery (group 2), radiotherapy (group 3) and chemotherapy (group 4). Descriptive statistics were performed with the SPSS v24 program. ROC curve was used to define cut point, sensitivity (S) and specificity (E).

Results: When analyzing, without discriminating by groups, an ROC curve with a cut-off point of 3.150, S 50% and E 60% was found, values that are neither discriminatory nor useful to define tumor viability. When analyzing the group of surveillance and rescue surgery, S 80% and E 82% were obtained. When compared with groups 3 and 4, they had a cut-off point of 3,150 and 2,350, respectively.

Conclusions: First study carried out in the country, the 18 FDG-PET / CT demonstrated a very poor utility for discriminating tumor viability in post-chemotherapy seminomatous residual masses, improving the results for the rescue and surveillance groups.