Changes in salivary gland function after radiotherapy of head and neck tumors measured by quantitative pertechnetate scintigraphy: comparison of intensity-modulated radiotherapy and conventional radiation therapy with and without Amifostine.
OBJECTIVE
The aim of this study was to compare changes in salivary gland function after intensity-modulated radiotherapy (IMRT) and conventional radiotherapy (RT), with or without Amifostine, for tumors of the head-and-neck region using quantitative salivary gland scintigraphy (QSGS).


METHODS
A total of 75 patients received pre- and post-therapeutic QSGS to quantify the salivary gland function. In all, 251 salivary glands were independently evaluated. Changes in the maximum uptake (DeltaU) and relative excretion rate (DeltaF) both pre- and post-RT were determined to characterize radiation-induced changes in the salivary gland function. In addition, dose-response curves were calculated.


RESULTS
In all groups, maximum uptake and relative excretion rate were reduced after RT (DeltaU <or=0 and DeltaF <or=0). The reduction was significantly lower for IMRT than for conventional RT. For the parotid glands, the reduction was smaller for the IMRT-low than for the IMRT-high group. For the Amifostine-high and the conventional group the difference was significant only for one parameter (DeltaU, parotid and submandibular glands, p < 0.05). In contrast to this, the difference between the Amifostine-low and the conventional group was always significant or at least showed a clear trend for both changes in U and F. In regard to the endpoint "reduction of the salivary gland excretion rate of more than 50%," the dose-response curves yielded D50-values of 34.2 +/- 12.2 Gy for the conventionally treated group and 36.8 +/- 2.9 Gy for the IMRT group. For the Amifostine group, an increased D50-values of 46.3 +/- 2.3 Gy was obtained.


CONCLUSIONS
Intensity-modulated RT can significantly reduce the loss of parotid gland function when respecting a certain dose threshold. Conventional RT plus Amifostine prevents reduced salivary gland function only in the patient group treated with <40.6 Gy.
Münter
Marc W
MW
Department of Radiation Oncology, University of Heidelberg, Heidelberg, Germany. m.muenter@dkfz.de
Hoffner
Simone
S
Hof
Holger
H
Herfarth
Klaus K
KK
Haberkorn
Uwe
U
Rudat
Volker
V
Huber
Peter
P
Debus
Jürgen
J
Karger
Christian P
CP
D000328:Adult; D000368:Aged; D004999:Amifostine / Q000627:therapeutic use; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000000981:diagnostic imaging / Q000528:radiation effects; D011837:Radiation-Protective Agents / Q000627:therapeutic use; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012469:Salivary Glands / Q000000981:diagnostic imaging / Q000528:radiation effects*; D012472:Salivation / Q000528:radiation effects; D013670:Sodium Pertechnetate Tc 99m; D014987:Xerostomia / Q000000981:diagnostic imaging / Q000209:etiology
D011837:Radiation-Protective Agents; D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m; D004999:Amifostine