Salivary Gland Function Five Years after a Radioiodine Ablation in Patients with Differentiated Thyroid Cancer: Direct Comparison of Pre and Post-Ablation Scintigraphies and Their Relation to Xerostomia Symptoms.
Thyroid : official journal of the American Thyroid Association | 17 Nov 2012
SY Jeong, HW Kim, SW Lee, BC Ahn and J Lee
Background Chronic sialadenitis is one of the most frequent chronic complications after radioiodine (RAI) therapy for thyroid cancer. To evaluate the long-term effects of RAI ablation on salivary gland function, we investigated scintigraphic changes in salivary glands by direct comparison of two salivary gland scintigraphies (SGS) taken before and at 5 yrs after a RAI ablation. Methods SGS was performed just before RIA (pre-SGS) and approximately 5 years after RAI ablation (F/U SGS) in 213 subjects who underwent thyroidectomy for thyroid cancer. The uptake score (US) was graded, and the ejection fraction (EF) was quantified for the parotid and submandibular glands at pre-SGS and F/U SGS. Changes in salivary gland function were graded as mild, moderate, or severe according to the differences in US and EF between the two SGS. Xerostomia were assessed and compared with the SGS findings. Results Worsening of the US was observed in 182 of 852 salivary glands (total: 21.3%; mild: 4.2%, moderate: 7.4%, severe: 9.7%), and 47.4% of the patients showed a worsening US for at least 1 of 4 salivary glands. A decrease in EF was observed in 173 of 852 salivary glands (total: 20.3%; mild: 5.4%, moderate: 6.8%, severe: 8.1%), and 43.7% of the patients experienced a decrease in the EF of at least 1 of the 4 salivary glands. Bilateral parotid gland dysfunction was the most commonly observed condition. Thirty-five (16.4%) patients complained of xerostomia at 5 years after RAI ablation. Scintigraphic changes in salivary gland function and xerostomia were more common in patients receiving 5.55 GBq, compared with 3.7 GBq. Xerostomia were more common in patients with submandibular gland dysfunction than those with parotid gland dysfunction (68.8% vs. 33.3%, P<0.05). The number of dysfunctional salivary glands was correlated with xerostomia (P<0.01). Conclusion About 20% of the salivary glands were dysfunctional on SGS at 5 years after a single RAI ablation, especially in patients who received higher doses of radioiodine. While parotid glands are more susceptible to I-131 related damage, xerostomia was more associated with submandibular gland dysfunction and the prevalence of dysfunctional salivary glands.
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