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

CONTEXT: Sialadenitis and xerostomia are major adverse effects of (131)I therapy in thyroid cancer patients. The risk factors for these adverse effects, other than administered activity of (131)I, have not been investigated. OBJECTIVE: The aim of this study is to identify risk factors for (131)I-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: (131)I treatment associated with higher incidence of xerostomia and sialadenitis. Patients with xerostomia had 46 mCi higher mean cumulative (131)I activity and 21 mCi higher mean first-administered (131)I 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 (131)I therapy had higher sialadenitis incidence after (131)I therapy. (131)I-treated patients diagnosed with AID-SS, whether before or after (131)I treatment, had a higher incidence of xerostomia and sialadenitis among (131)I-treated patients. CONCLUSION: Risk factors for (131)I-induced salivary gland damage include administered (131)I activity, age, gender, history of sialadenitis before (131)I treatment, and AID-SS diagnosis.