INTRODUCTION:Precision radiotherapy relies heavily on optimal weight management. Our group previously developed a risk stratification model for patients at risk of prolonged feeding tube (FT) intervention. The study objective was to assess on-treatment weight loss according to stratified risk of prolonged FT use. METHODS:One hundred and one (n = 101) definitive head and neck radiotherapy patients were included in this study. Patients were stratified into high risk (HRi: T-classification ≥ 3 with level 2 Nodal disease), high-intermediate risk (HIRi: T-classification ≥ 3 without level 2 Nodes) and low-intermediate risk (LIRi: T-classification < 3 with level 2 Nodes) of prolonged FT use. Demographic variables and on-treatment weight loss were evaluated according to risk status. RESULTS:Oropharyngeal carcinoma (OPC) was present in a larger proportion in the LIRi cohort (HRi: 71%, HIRi: 52%, LIRi: 81%, P = 0.008). LIRi patients were more likely to have human papilloma virus (HPV)-associated disease (88%, P = 0.001). Never/minimal smoking (P = 0.003), good performance status (P < 0.001), healthy BMI (P = 0.050) and no pre-existing dysphagia (P < 0.001) were predominant within the LIRi prognostic group. LIRi patients lost significantly more weight in total (HRi = 4.8% vs. LIRi = 8.2%, P = 0.002; HIRi = 5.2% vs. LIRi = 8.2%, P = 0.006) and when using a FT (HRi = 4.6% vs. LIRi = 8.8%, P < 0.001; HIRi = 5.3% vs. LIRi = 8.8%, P = 0.002). CONCLUSIONS:Patients identified as low-intermediate risk of prolonged, ≥25% FT use report significantly increased weight loss compared with patients at higher risk of FT use. This cohort is typical of the increasing number of patients presenting with HPV-associated OPC. Results of this study suggest we should closely observe such patients throughout treatment, to ensure optimal weight maintenance, facilitating precision radiotherapy.