Comparative Analysis of Parotid Doses in Tomotherapy Versus Volumetric Modulated Arc Therapy for Head and Neck Cancer Patients Undergoing Bilateral Neck Irradiation: A Non-randomized, Prospective, Dosimetric and Clinical Study

Abstract

Background and Objectives: Xerostomia, a common side effect of head and neck radiation therapy, significantly impacts subjective well-being and quality of life. Its severity depends on the radiation dosage received by the parotids. Advanced techniques like Volumetric Modulated Arc Therapy (VMAT) and Tomotherapy offer improved parotid sparing. This prospective, non-randomized, double arm, dosimetric, and clinical study aims to compare parotid dosages between Tomotherapy and VMAT (Rapid Arc) in head and neck cancer patients undergoing bilateral neck irradiation. Methods: Fifty-two eligible patients were included, with 26 treated by Tomotherapy and 26 by VMAT. Plans were cross planned between the two techniques while maintaining similar Planning Target Volume (PTV) coverage. Bilateral parotid dosages were evaluated, and clinical xerostomia assessment utilized the Xerostomia Questionnaire (XQ) and Radiation Therapy Oncology Group (RTOG) scoring criteria. Statistical analysis employed the paired t-test. Results: Both right and left parotids received significantly lower mean doses on Tomotherapy (21.23Gy ± 4.429) compared to VMAT (23.26Gy ± 4.531) (p < 0.001). XQ scores and RTOG scores did not show statistically significant differences between the two arms at both follow-ups. Tomotherapy demonstrated better parotid sparing, translating into reduced acute salivary gland morbidities. Conclusion: This study highlights Tomotherapy's superiority in parotid sparing over Rapid Arc (VMAT), leading to clinically relevant reductions in xerostomia. Notably, oral cavity cancer patients exhibited higher xerostomia scores, emphasizing the importance of minor salivary glands. Long-term follow-up, extending to at least 2 years post-radiotherapy, is crucial for a comprehensive assessment of the technique's advantage in reducing xerostomia and improving quality of life.