Quantification of salivary gland function in thyroid cancer patients treated with radioiodine

Abstract

Purpose : Damage to salivary gland function following external irradiation has been documented. However, the extent of damage following radioiodine ( 131I) therapy for thyroid cancer has not been adequately studied. We evaluated salivary dysfunction in Ca-thyroid patients treated with therapeutic doses of 131I. Methods and Materials : A simple acquisition and analysis protocol using 99mTcO − 4 (pertechnatate) and a gamma camera computer system was planned. The uptake of 99mTcO − 4 by the salivary glands at 10 min and percent of excretion of 99mTcO − 4 from the glands in response to a sialogogue (lemon juice) was studied in 33 patients treated with 1.369−38.702 GBq of 131I (Mean = 10.16 GBq, standard deviation = 7.659 GBq) in addition to 14 athyreotic controls. Results : Significant damage to the salivary gland in terms of abnormal percent uptake or excretion was noted in 72.73% of the patients. Forty-eight percent of the patients treated with 131I showed asymmetrical involvement of the salivary complexes as opposed to none of the controls. Reduction in uptake of 99mRcO − 4 or response to sialogogue was dose dependent, being more marked with higher radioiodine doses. Parotid glands were more affected than submandibular glands following 131I therapy. Conclusions : 131I therapy produces a significant effect on salivary gland function that is dose related and becomes evident over a period of several months after treatment.