The dental safety profile of high-dose radioiodine therapy for thyroid cancer: long-term results of a longitudinal cohort study

The long-term dental safety profile of high-dose radioiodine therapy remained elusive despite more than 6 decades of clinical use. METHODS: In a cohort study, we investigated the incidence of sialadenitis, xerostomia, caries, and tooth extractions after high-dose radioiodine therapy for differentiated thyroid cancer and explored risk factors by multiple regression models. RESULTS: One hundred seventy-six participants were recruited (median follow-up, 6.6 y; range, 1.1-32.6 y; patient-years: 8,472 before and 1,421 after radioiodine therapy). Scintigraphic salivary gland uptake during radioiodine treatment predicted development of sialadenitis (odds ratio: 1.31 [1.05-1.63], P = 0.015) and xerostomia (odds ratio: 1.58 [1.16-2.16], P = 0.004). The caries risk increased by postradioiodine xerostomia (% increase: 98.8 [26.5-212], P = 0.003). The long-term risk for postradioiodine tooth extractions increased with increasing cumulative radioiodine activities (% increase [per gigabequerel]: 8.14 [1.07, 15.7], P = 0.02). CONCLUSION: High-dose radioiodine treatment can impair the long-term dental health, depending on the cumulative radioiodine activity and individual salivary gland radioiodine uptake.