ADAPTIVE DOSE PAINTING BY NUMBERS FOR HEAD-AND-NECK CANCER

Purpose: To investigate the feasibility of adaptive intensity-modulated radiation therapy (IMRT) using dose painting by numbers (DPBN) for head-and-neck cancer. Methods and Materials: Each patient's treatment used three separate treatment plans: fractions 1-10 used a DPBN ([(18)-F]nuoro-2-deoxy-D-glucose positron emission tomography [F-18-FDG-PET]) voxel intensity-based IMRT plan based on a pretreatment F-18-FDG-PET/computed tomography (CT) scan; fractions 11-20 used a DPBN plan based on a F-18-FDG-PET/CT scan acquired after the eighth fraction; and fractions 21-32 used a conventional (uniform dose) IMRT plan. In a Phase I trial, two dose prescription levels were tested: a median dose of 80.9 Gy to the high-dose clinical target volume (CTVhigh_dose) (dose level I) and a median dose of 85.9 Gy to the gross tumor volume (GTV) (dose level II). Between February 2007 and August 2009, 7 patients at dose level I and 14 patients at dose level II were enrolled. Results: All patients finished treatment without a break, and no Grade 4 acute toxicity was observed. Treatment adaptation (i.e., plans based on the second F-18-FDG-PET/CT scan) reduced the volumes for the GTV (41.%, p = 0.01), CTVhigh_dose (18%, p = 0.01), high-dose planning target volume (14%, p = 0.02), and parotids (9-12%, p < 0.05). Because the GTV was much smaller than the CTVhigh_dose and target adaptation, further dose escalation at dose level II resulted in less severe toxicity than that observed at dose level I. Conclusion: To our knowledge, this represents the first clinical study that combines adaptive treatments with dose painting by numbers. Treatment as described above is feasible. (C) 2011 Elsevier Inc.