Risk Factors of 131I-Induced Salivary Gland Damage in Thyroid Cancer Patients

Context: Sialadenitis and xerostomia are major adverse effects of I-131 therapy in thyroid cancer patients. The risk factors forthese adverse effects, otherthan administered activity of I-131, have not been investigated. Objective: The aim of this study is to identify risk factors for I-131-induced salivary gland damage among follicular cell-derived thyroid cancer patients. Design: We enrolled 216 thyroid cancer patients who visited The Ohio State University Wexner Medical Center between April 2013 and April 2014. Symptoms of xerostomia and sialadenitis were identified via questionnaire and medical record search. To validate the findings in a large cohort, we retrospectively searched for ICD-9/10 codes for sialadenitis, xerostomia, and autoimmune disease associated with Sjogren's syndrome (AID-SS) in our existing database (n = 1507). Demographic and clinical information was extracted from medical records. Multivariate analyses were performed to identify independent predictors for salivary gland damage. Results: I-131 treatment associated with higher incidence of xerostomia and sialadenitis. Patients with xerostomia had 46 mCi higher mean cumulative I-131 activity and 21 mCi higher mean first administered I-131 activity than patients without xerostomia. Increased age associated with higher incidence of xerostomia, and females had a higher incidence of sialadenitis. Patients who experienced sialadenitis before I-131 therapy had higher sialadenitis incidence after I-131 therapy. I-131 treated patients diagnosed with AID-SS, whether before or after I-131 treatment, had a higher incidence of xerostomia and sialadenitis among I-131-treated patients. Conclusion: Risk factors for I-131-induced salivary gland damage include administered I-131 activity, age, gender, history of sialadenitis before I-131 treatment, and AID-SS diagnosis.