Longitudinal assessment of parotid function in patients receiving tomotherapy for head-and-neck cancer

Abstract

Background and purpose: Conventional radiotherapy is associated with high doses to the salivary glands which causes xerostomia and adverse effects on quality of life. The study aims to investigate the potential of helical tomotherapy (Hi-Art Tomotherapy) to preserve parotid function in head-and-neck cancer patients.

Patients and methods: Seven consecutive patients treated with helical tomotherapy at the UZ Brussel, Belgium, were included. During planning, priority was attributed to planning target volume (PTV) coverage: > or =95% of the dose must be delivered to > or =95% of the PTV. Elective nodal regions received 54 Gy (1.8 Gy/fraction). A dose of 70.5 Gy (2.35 Gy/fraction) was prescribed to the primary tumor and pathologic lymph nodes = simultaneous integrated boost scheme. If possible, the mean parotid dose was kept below 26 Gy. Salivary gland function was assessed by technetium scintigraphy.

Results: There was a significant dose-response relationship between mean parotid dose and functional recuperation. If the mean dose was kept <31 Gy, a recuperation of 75% can be expected at 12 months. The authors equally observed a significant correlation between salivary excretion (SE) and the percentage of parotid gland receiving a dose <26 Gy (V26%). In order to preserve 75% of SE, 46% of the parotid volume should receive a dose <26 Gy.

Conclusion: With the use of heLical tomography the parotid gland function can largely be preserved since the mean dose to the entire gland as well as glandular volume receiving >26 Gy can be reduced.