The effect of an intensive nutritional program on daily set-up variations and radiotherapy planning margins of head and neck cancer patients

This is a prospective case-control study to assess nutritional supplementation in limiting weight loss and its impact on daily set-up variations and planning target volume (PTV) margins in head and neck (H&N) radiotherapy (RT). Twenty sequential H&N patients were recruited for this study. Ten patients had a percutaneous endoscopic gastrostomy (PEG) tube inserted prior to RT and 10 did not. PEG use was determined by departmental guidelines for patients considered at high risk for weight loss. Daily 2D electronic portal images were taken for orthogonal verification. Set-up variations were determined for both PEG and non-PEG patients by calculating systematic (Sigma) and random (sigma) errors, and PTV margins were derived. PEG patients lost less weight (P = 0.04) over the course of RT and had a reduction in set-up variation in the superior-inferior (SI) and anterior-posterior (AP) planes compared to those without. Mean correctional shifts in mm (range) for PEG patients were: Right-Left (RL) 0.1 (-1.9-2.1), SI -1.7 (-2.9-0.0), AP -0.4 (-2.0-0.8), and for non-PEG patients were: RL -0.2 (-2.7-1.3), SI -1.3 (-3.1-1.0), AP 0.4 (-1.5-2.8). The adapted PTV margins (mm) in the RL, SI and AP planes, respectively, for PEG patients were 4.1, 3.3 and 3.6, and for non-PEG were 3.9, 4.9 and 4.8. Intensive enteral support maintained weight stability in H&N patients considered at risk of weight loss during RT and this was associated with reduced set-up variation.