The aim of the study was to analyze the diagnostic and prognostic utility of 18F-FDG PET/CT to predict the disease-specific survival (DSS) with FDG uptake and tumor grade in recurrent chondrosarcoma.
Retrospective analysis of FDG PET/CT findings in 31 previously treated patients (46 studies) with mean follow-up period of 40.7 ± 23.9 months (range, 3–77 months) from the date of first PET/CT study was done. Kaplan-Meier DSS analysis was made with respect to tumor grade, FDG uptake at the recurrent primary sites, and a combination of grade and FDG uptake as parameters.
Recurrence (local and distant) was shown in 28 (60.8%) of 46 FDG PET/CT studies with sensitivity and specificity of 88.9% and 78.9%, respectively. The median SUVmax at the recurrent primary sites differed significantly (P = 0.008) among 3 tumor grade groups, with higher median SUVmax in higher grades. There was significant difference in median SUVmax among different grade groups except between grade II and grade III. Recurrent primary site SUVmax cutoff at 6.15 derived from the receiver operating characteristic curve yielded significant difference (P < 0.001) in mean DSS time. Significant difference in survival was noted between 3 different tumor grade groups (P = 0.016). The combination of SUVmax and grade improved the survival prediction than with grade alone.
In recurrent chondrosarcoma, the recurrent primary site FDG uptake and grade were found to be reliable prognostic factors with respect to DSS. PET/CT in recurrence setting has the potential to predict tumor grade and survival and may assist in clinical management.
From the Departments of *Nuclear Medicine, †Histopathology, and ‡Orthopedics, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Received for publication September 26, 2017; revision accepted November 24, 2017.
Conflicts of interest and sources of funding: none declared.
This single-institution retrospective study was approved by the institutional ethical committee. Informed consent was waived because of the retrospective nature of the study. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Correspondence to: Ashwani Sood, DNB, Department of Nuclear Medicine, Postgraduate Institute of Medical Education and Research, Kairon Block, Sector 12, Chandigarh 160012, India. E-mail: email@example.com.