Maximum tolerated dose in a phase I trial on adaptive dose painting by numbers for head and neck cancer

Purpose: To determine the maximum tolerated dose (MTD) in a phase I trial on adaptive dose-painting-by-numbers (DPBN) for non-metastatic head and neck cancer. Materials and methods: Adaptive intensity-modulated radiotherapy was based on voxel intensity of pre-treatment and per-treatment [(18)F]fluoro-2-deoxy-D-glucose positron emission tomography ((18)F-FDG-PET)/CT scans. Dose was escalated to a median total dose of 80.9 Gy in the high-dose clinical target volume (dose level I) and 85.9 Gy in the gross tumor volume (dose level II). The MTD would be reached, if >= 33% of patients developed any grade >= 4 toxicity (DLT) up to 3 months follow-up. Results: Between February 2007 and August 2009, seven patients at dose level I and 14 at dose level II were treated. All patients completed treatment without interruption. At a median follow-up for surviving patients of 38 (dose level I) and 22 months (dose level II) there was no grade >= 4 toxicity during treatment and follow-up but six cases of mucosal ulcers at latency of 4-10 months, of which five (36%) were observed at dose level II. Mucosal ulcers healed spontaneously in four patients. Conclusions: Considering late mucosal ulcers as DLT, the MTD of a median dose of 80.9 Gy has been reached in our trial. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 101 (2011) 351-355