RESUMO
PURPOSE: This prospective study reports the impact of weight loss on setup of head and neck (H&N) cancer patients treated by Intensity-Modulated Radiation Therapy (IMRT). MATERIALS AND METHODS: Setup errors of H&N cancer patients treated by IMRT from January to June 2010 were prospectively analysed and statistically related to weight loss. A mixed linear model was used for statistical evaluations. Setup margins of our institute were also calculated. RESULTS: Twenty-two patients and 128 pairs of Electronic Portal Images (EPI) were analysed. Setup errors varied between -0.6 and +0.6, -0.7 and +0.8 and -0.2 and +0.8 in the anterior-posterior, superior-inferior and right-left direction, respectively. Median and mean weight loss were 2.1 and 3.1 kg (range 0-12 kg), respectively; median and mean percent of weight loss were 2.95% and 4.64% (range 0.3-19.7%), respectively. No statistical relation was seen between weight loss and the setup errors. CONCLUSIONS: Weight loss is not a good clinical parameters for predicting an increase of setup errors. Other clinical and/or anthropometrical features should be prospectively evaluated in order to assess the need for re-planning.