Salivary and Lacrimal Disorders in Patients Treated with Radioiodine for Differentiated Thyroid Cancer: Systematic Review and Meta-Analyses

Radioactive iodine therapy (RIT) is commonly used as an adjuvant treatment for differentiated thyroid cancer (DTC). While its efficacy is well established, this therapy can cause radiation-induced damage to the salivary and lacrimal glands due to their ability to concentrate iodine. These adverse effects may lead to xerostomia, sialadenitis, or xerophthalmia. The aim of this review and meta-analysis was to estimate the prevalence and characteristics of salivary and lacrimal dysfunctions in patients treated with RIT for DTC. Following PRISMA guidelines, a systematic search was conducted in PubMed and Scopus databases to identify studies published between 2000 and 2024. Meta-analyses of prevalence and odds ratios were carried out using random-effects models to estimate the pooled prevalence of events and the influence of administered activity. Thirty-eight studies were included in the review, of which sixteen were retained for the meta-analyses. The pooled prevalence of xerostomia decreased from 60% (95%CI 28;85) at <2 months to 17% (95%CI 10;28) more than one year post-RIT. A significant association was observed between high levels- with study-specific thresholds - of administered I131 activity and the occurrence of xerostomia. Sialadenitis and lacrimal dysfunction were also frequently reported. Despite heterogeneity in protocols and assessment tools, most studies highlighted a frequently persistent impairment in many patients. This systematic review and meta-analysis highlighted the frequency and persistence of salivary and lacrimal dysfunctions following RIT.