[Salivary gland damage after 131I therapy in patients with differentiated thyroid cancer. Preliminary report]

The purpose of the study was to evaluate salivary gland dysfunction after a high-dose radioiodine therapy administered to patients with differentiated thyroid carcinoma.

The study group consisted of 60 patients (age range 20-78 years). Detailed history about complaints from the oral cavity were taken, followed by the ultrasonography and dynamic scintigraphy. The procedure was performed on 40 patients before and one year after radioiodine administration, and a single-time on 20 patients treated with multiple doses in the past.

Data analysis shows no statistically significant increase of subjective sufferings after first radioiodine dose (60-150 mCi), small decrease of uptake ratio UR (< 10%) and diminished parotid glands transverse diameter (approximately 10%). The patients after multiple therapies (i.e. average dose of 250 mCi) informed more often about problems connected with decreased salivation (approximately 20% patients), in scintigraphy there was a reduction of parotid UR 21-23% and parotid maximal secretion MS 7-13%. Ultrasonography did not show changes in salivary glands echogenicity after 12 months from the first dose of 131I. There was no close relationship between scintigraphically revealed dysfunctions and the occurrence of complaints; no correlation between appearance of acute sialadenitis symptoms after radioiodine therapy and subsequent dysfunctions.

The main conclusion is that a single dose of 131I has no significant influence on salivary gland function; a repeated high-doses therapy is connected with an essential risk of side-effect occurrence. Scintigraphy can evaluate salivary gland function with high sensitivity. Parotid glands are more radiosensitive than submandibular.