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A.W. Larsen
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P2.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 234)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P2.04-035 - Methods for Evaluating Early Response to Erlotinib Treatment Using FDG-PET/CT (ID 2865)
09:30 - 09:30 | Author(s): A.W. Larsen
- Abstract
Background:
Early evaluation of response to treatment with Fluoro-deoxy-glucose-Positron-Emission-Tomograpy-CT (FDG-PET/CT ) is increasing rapidly, but which method is the ideal to use is not clear. In this study early response (1-2 weeks) evaluation was performed using three different methods and compared to clinical response at three months.
Methods:
Forty-three patients with metastatic pulmonary adenocarcinoma had FDG-PET/CT scans performed prior to erlotinib treatment and after 1-2 weeks of treatment. The scans were evaluated by one experienced nuclear medicine specialist. The scans were evaluated by three different methods using Siemens Syngovia software: Visual evaluation, as according to Hicks et al, % change in SULpeak as according to PERCIST 1.0 , and finally calculating the % change in total tumor glycolysis (TLG) proposed in PERCIST 1.0. The early response was compared to response on CT at 12 weeks and to progression free survival (PFS)
Results:
The results are shown in figure 1. Defining response as “not progression” on CT at 12 weeks (10 in total), visual evaluation identifies 6 correctly, and 5 of 33 non-responders as responders. One patient classified as a responder who had a PFS of 0.9 months, had stopped treatment because of side effects. The SULpeak method identifies the same 6 responders correctly, and 3 of 33 non-responders as responders. TLG change identifies 4 responders correctly and 3 of 33 non-responders as responders. Looking at early progression (16 in total) , visual evaluation identified 6 correctly, The SULpeak method identified 4 correctly, the TLG method identified 2 early progressions correctly. Figure 1 Table 1: Response groups by patient, ordered by PFS (in months) as found by the three methods. 1 partial response, 2 stable disease and 3 progression. “true” progression and response values are highlighted in bold. Division lines in bold separates response and early progression from the middle group as according to PFS and CT. * Not Available, ** treatment stopped early because of side effects .
Conclusion:
Visual evaluation identified more responders and patients with early progression during treatment with erlotinib. The more objective method based on calculation of SUV calculations identified less responders as well as less patients with early progression, suggesting a lower sensibility for this method. This suggests that the 40% cut off in % change used in this study (as suggested by Wahl et al in the PERCIST criteria), and perhaps the 30% cut off used for SULpeak change are too high for very early evaluation.
