Preservation of parotid function with uncomplicated conformal radiotherapy.
OBJECTIVE
To evaluate (1) parotid function, (2) subjective xerostomia and (3) pattern of relapses after conformal parotid-sparing radiotherapy (RT) for head and neck cancer. (4) To study dose-response curves of parotid glands.


METHODS
From September 1999 to November 2000, 39 head and neck cancer patients requiring bilateral neck RT were treated with a fairly simple conformal RT technique (three-field set-up+anterior lower neck field; two opposed oblique boost fields). The contralateral parotid was spared. Parotid function was assessed by salivary gland scintigraphies performed before, early (median 4 weeks) and late (median 28 weeks) after RT. Xerostomia was monitored by visual analogue scales (VAS) and LENT SOMA scores. Location of locoregional recurrences was studied in relation to the radiation fields. A dose-response curve of parotids was created using logistic regression.


RESULTS
(1) Early after RT, on salivary gland scintigraphy, the mean loss of secretion function in the spared parotid was 67% and total in the non-spared. Late after RT, the mean loss remained 19% in the spared and total in the non-spared parotid. Normal excretion function was regained in 75% of the spared parotids. (2) Late after RT, 78% of patients had no, minimal or acceptable subjective xerostomia. (3) No recurrence was seen near the spared parotid (11/39 locoregional recurrences). (4) The dose-response curve of parotids showed that the mean parotid dose should preferentially be < or =20 Gy, to obtain a good chance (> or =70%) for preservation of its function on scintigraphy.


CONCLUSIONS
An easy conformal parotid-sparing RT technique prevents moderate or severe subjective xerostomia in 78% of patients. In the spared parotids, nearly complete to complete recovery is obtained after 6-12 months.
Maes
Annelies
A
Department of Radiation Oncology, University Hospital Gasthuisberg, Herestraat 49, B-3000, Leuven, Belgium.
Weltens
Caroline
C
Flamen
Patrick
P
Lambin
Philippe
P
Bogaerts
Ria
R
Liu
Xuan
X
Baetens
Jan
J
Hermans
Robert
R
Van den Bogaert
Walter
W
D000328:Adult; D000368:Aged; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000000981:diagnostic imaging / Q000378:metabolism / Q000528:radiation effects*; D011832:Radiation Injuries / Q000517:prevention & control; D011877:Radionuclide Imaging; D020266:Radiotherapy, Conformal / Q000009:adverse effects; D012463:Saliva / Q000378:metabolism; D014987:Xerostomia / Q000209:etiology