Prospective evaluation of dose rate effects on acute radiation toxicities and quality of life in head and neck cancer

PURPOSE: This study evaluates the influence of different dose rates on the radiation-related adverse events. MATERIALS AND METHODS: The study involved 60 patients divided into three groups, each receiving different dose rates of the Flattening Filter-Free (FFF) 6MV IMRT technique: 20 patients at 600, 20 at 1000, and 20 at 1400. Acute adverse events were monitored weekly. The EORTC-translated QLQ-H&N 35 questionnaire was used to assess health-related quality of life (QoL) according to established EORTC criteria during radiotherapy. RESULTS: During the initial phase of radiotherapy treatment, no significant differences were noted in the prevalence of conditions such as mucositis and weight loss among the treatment groups. However, weight loss showed a significant variation (p = 0.028) at third week for the 600-dose rate group. From the fourth to fifth week, no notable differences emerged for mucositis and xerostomia among groups, while increase radiation dose rate was correlated with significant rise in dermatitis and dysphagia (p = 0.020 and p = 0.036, respectively). Similarly, from week five to six and from week six to seven, no significant differences were observed for mucositis. Yet significant increase in xerostomia and other conditions was evident with rising radiation dose rate. The evaluation of the QLQ-H&N 35 for head and neck cancer patients revealed a numerical scale for symptom severity, from 1 (not at all) to 4 (very much). While differences in symptom intensity across dose rates were noted, they did not reach statistical significance. CONCLUSION: The dose rate appears to influence patient health outcomes, although it does not seem to affect the QoL during the period of radiotherapy course treatment.