QUANTIFICATION OF SALIVARY-GLAND FUNCTION IN THYROID-CANCER PATIENTS TREATED WITH RADIOIODINE

Purpose: Damage to salivary gland function following external irradiat ion has been documented, However, the extent of damage following radio iodine (I-131) therapy for thyroid cancer has not been adequately stud ied, We evaluated salivary dysfunction in Ca-thyroid patients treated with therapeutic doses of I-131.Methods and Materials: A simple acquis ition and analysis protocol using (TcO4-)-Tc-99m (pertechnatate) and a gamma camera computer system was planned, The uptake of (TcO4-)-Tc-99 m by the salivary glands at 10 min and percent of excretion of (TcO4-) -Tc-99m from the glands in response to a sialogogue (lemon juice) was studied in 33 patients treated with 1.369-38.702 GBq of I-131 (Mean = 10.16 GBq, standard deviation = 7.659 GBq) in addition to 14 athyreoti c controls. Results: Significant damage to the salivary gland in terms of abnormal percent uptake or excretion was noted In 72.73% of the pa tients, Forty-eight percent of the patients treated with I-131 showed asymmetrical involvement of the salivary complexes as opposed to none of the controls, Reduction in uptake of (TcO4-)-Tc-99m or response to sialogogue was dose dependent, being more marked with higher radioiodi ne doses, Parotid glands were more affected than submandibular glands following I-131 therapy. Conclusions: I-131 therapy produces a signifi cant effect on salivary gland function that is dose related and become s evident over a period of several months after treatment.