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Oncology-Clinical Diagnosis: Solid TumorsLung Cancer I |
1 Radiation Oncology, Academic Hospital Maastricht/Maastro Clinic/GROW, Maastricht, Netherlands
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Objectives: To improve radiotherapy by combined FDG-PET-CT.
Methods: PET-CT based radiation.
Results: 1. Using PET-CT instead of CT alone, for the same toxicity levels of the lung, esophagus and spinal cord, the radiation dose could be increased from 55.2 +/- 2.0Gy with CT to 68.9 +/- 3.3Gy with PET-CT (p=0.002), with corresponding TCP's (Tumor Control Probability) of 6.3 +/- 1.5% for CT and 24.0 +/- 5.6% for PET-CT planning (p=0.01). 2. In a phase II trial we showed that selective irradiation on basis of PET-CT was safe with only 2.3% (upper bound 95% CI, 10.3%) developing an isolated nodal failure. PET-CT allowed radiation dose escalation with low toxicity. Metabolic complete remission was obtained in 75 % (95 % CI 70-80) of patients. 3. SBR-based auto-contour (AC) correlated strongly with pathological size (correlation coefficient = 0.90) and was shown to be accurate for involved lymph nodes (sensitivity 67%, specificity 95%). AC reduced inter-and intra-observer variability of tumor delineation (Concordance Index: 0.74 and 0.70; p < 0.001). 4. To reduce cost we showed A. the feasibility to use the staging PET-CT scans and B. that PET-based AC reduced time needed for the radiation oncologist to delineate the tumor: 23.3 +/- 7.2 min manually (S.D) vs.14.7 +/- 6.4 min. with AC; p=0.018. 5. We showed that FDG-PET-CT allows the identification of the (chemo)-radiation resistant areas within the tumor before therapy (Fig).
Conclusions: PET-CT thus allows more accurate and faster delineation of the tumor, increased tumor control, without increased toxicity and without increased costs. Many more gains are expected in the near future.
Research Support: Siemens
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