2002 CTOS Annual Meeting Oral Presentations — Diagnostic Radiology

FDG- POSITRON EMISSION TOMOGRAPHY (PET) IN STAGING AND MANAGING PATIENTS WITH SOFT TISSUE SARCOMAS
[Abstract ID: 61]

Category: Diagnostic Radiology

Presentation: Oral

Authors: Thomas F. DeLaney¹, Francis J. Hornicek¹, Mark C. Gebhardt¹, Mark J. Ott¹, Alan Fischman¹, Peter A. Chapman¹, Andrew R. Rosenberg¹, Daniel I. Rosenthal¹, David C. Harmon¹, Herman D. Suit¹

Author Institutions: ¹Massachusetts General Hospital, MA, United States

Presenter: Thomas F. DeLaney
tdelaney@partners.org

Correspondent: Thomas F. DeLaney
tdelaney@partners.org
Boston MA United States 02114
Ph: 617-726-7869
Fax: 617-724-9532

Objectives: FDG (2-18fluoro-2-deoxy-D-glucose) PET scanning is useful for oncologic staging and treatment assessment. We evaluated its role in patients with soft tissue sarcomas.

Methods: 59 patients underwent 97 PET scans, 50 at initial staging, which included primary site MRI and chest CT. PET activity was scored as 0=normal, 1= minimal, 2=moderate, and 3= intense. PET results were compared with chest CT to assess sensitivity /specificity. Most patients underwent neoadjuvant radiation or chemoradiation followed 3-4 weeks later by surgery. Re-staging PET, MRI, and chest CT were performed 1-3 weeks after neoadjuvant therapy and PET activity in the primary site was correlated to residual tumor in the surgical specimen.

Results: Increased activity was seen at the primary site in 47 patients (94 %); median and mean activity scores were respectively 3 and 2.75. Two patients without PET activity had undergone excisional biopsy; a third had grade 1 liposarcoma. Sensitivity and specificity for PET for detecting lung metastases were 0.09 and 0.97 respectively, compared to 0.75 and 0.83 for chest CT. Positive and negative predictive values for PET were 0.50 and 0.77 compared to 0.56 and 0.92 for chest CT. On 39 re-staging PETs after neoadjuvant treatment, there was less activity, median score 2 and mean 2.18. No clear relationship emerged between residual activity and percent necrosis in the surgical specimen, although this has not yet been corrected for tumor grade.

Conclusions: Soft tissue sarcomas are FDG avid at the primary site; activity decreases with neoadjuvant therapy. PET scanning is not useful for detection of lung metastases.