Purpose: In this retrospective study, two approaches to preserve the parotid function after radiotherapy (RT) were compared: application of the radioprotective agent amifostine during RT and parotid-sparing intensity-modulated radiotherapy (IMRT).
Patients and methods: Patients were qualified for this analysis if (1) both parotid glands received a radiation dose of >or=50Gy using conventional radiotherapy techniques (cRT) or if they received a parotid-sparing IMRT as alternative, if (2) salivary gland scintigraphies before and after RT were performed, and if (3) a normal parotid function was present before RT. Quantitative salivary gland scintigraphy was used to assess the parotid gland function.
Results: Altogether 275 salivary gland scintigraphies of 100 patients were analyzed. The mean relative tracer uptake (DeltaU) of patients treated with cRT, cRT with amifostine and IMRT 1-12 months after RT was 0.59 (95%CI 0.54-0.65), 0.67 (95%CI 0.59-0.76), and 0.93 (95%CI 0.78-1.07), respectively. The mean relative DeltaU 13-47 months after RT was 0.40 (95%CI 0.32-0.49), 0.60 (95%CI 0.48-0.71), and 0.92 (95%CI 0.56-1.28). At 1-12 months after RT, ANOVA testing with post-hoc comparison using the Bonferroni correction showed a significant difference between IMRT and cRT (p<0.001) or IMRT and amifostine (p<0.01). The difference between amifostine and cRT was not significant during the first year. At 13-47 months after RT, the difference between cRT and amifostine was significant (p=0.02).
Conclusion: Our data suggest that both amifostine and IMRT are able to partially preserve the parotid function after radiotherapy. The effect of IMRT appeared to be much greater.