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Oncology-Clinical Diagnosis: Solid TumorsClinical Diagnosis-Solid Tumors Posters |
1 Nuclear Medicine Unit; 2 Radiotherapy Unit; 3 Oncology Unit; 4 Surgery Unit; 5 Pathology Unit, S. Maria della Misericordia Hospital, Rovigo, Italy
1453
Objectives: To establish the diagnostic and prognostic role of FDG-PET in pts with locally advanced rectal cancet (LARC).
Methods: 81 pts with LARC were enrolled. Chemo-radiation therapy (CRT) consisted of PVI 5-FU (300 mg/m2/day) combined to external-beam intensified radiotherapy (50 Gy to the posterior pelvis, 56 Gy to the tumor). 8-10 later, pts underwent radical surgery. FDG-PET/CT was performed both before and 5-6 weeks after completion of CRT. FDG uptake (SUVmax), absolute difference (delta-SUVmax) and percent SUVmax difference (Response Index=RI) between pre- and post-CRT FDG-PET scans were considered.
Results: Following CRT, 40/81 pts (49%) were classified as responders according to Mandard’s criteria (TRG1-2). Mean pre-CRT SUVmax was 15.8, significantly higher than post-CRT SUVmax value = 5.9 (p<.001). The mean RI was significantly higher in responders than in non-responders (71.3% vs. 38%, p=0.0038). Using a RI cutoff of 65% for defining response to therapy n(ROC analysis), the following values were found for the FDG-PET/CT: 84.5% sensitivity, 80% specificity, 81.4% positive predictive value, 84.2% negative predictive value, and 81% overall accuracy.
Conclusions: Our data obtained in a large patient’s series suggest the potential utility of FDG-PET as a complementary diagnostic and predicitive procedure in the management of LARC. In this experience, RI was the best predictor in identifying CRT response.
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