The Dental Safety Profile of High-Dose Radioiodine Therapy for Thyroid Cancer: Long-Term Results of a Longitudinal Cohort Study

Abstract

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 5 0.015) and xerostomia (odds ratio: 1.58 [1.16-2.16], P 5 0.004). The caries risk increased by postradioiodine xerostomia (% increase: 98.8 [26.5-212], P 5 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 5 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.

Influence of Vitamin C on Salivary Absorbed Dose of 131I in Thyroid Cancer Patients: A Prospective, Randomized, Single-Blind, Controlled Trial

“…Recent reviews of adverse salivary effects after 131 I therapy have indicated an incidence of acute sialadenitis ranging from 24% to 67%, with chronic sialadenitis in 11%243% of those treated (2,8,9). Clinically relevant xerostomia, with dry mouth, swallowing difficulties, and a loss of taste, has, to a certain extent, impaired the quality of life of thyroid cancer patients (2,(4)(5)(6)(7)(8)(9). Therefore, prevention of salivary gland injury in 131 I therapy becomes an important issue.…”

“…Salivary glands are highly radiosensitive (3). Radiation sialadenitis and xerostomia have become the most frequent complication of high-activity 131 I therapy for thyroid cancer (2,(4)(5)(6)(7)(8)(9). Additionally, salivary gland injury can be observed even when the administered 131 I activity is relatively low (7)(8)(9).…”

Effects of Radioiodine Treatment on Salivary Gland Function in Patients with Differentiated Thyroid Carcinoma: A Prospective Study

“…Ongoing sialoadenitis can lead to atrophy of the secretory parenchyma and salivary gland fibrosis, which may result in decreased saliva flow rates (hyposalivation), sensation of a dry mouth (xerostomia), and an increased risk of oral infections and dental caries (7 ). A further loss of salivary gland function due to stem cell damage may become clinically manifest after 60-120 d, because this time is specific for salivary cell turnover (8).…”

Effect of Parotid Gland Massage on Parotid Gland Tc-99m pertechnetate Uptake

“…Recent reviews of adverse effects of 131 I therapy on salivary glands cite incidences of acute sialadenitis from 24% to 67% and of chronic sialadenitis from 11% to 43% (3)(4)(5)19). Clinically relevant xerostomia is characterized by a dry mouth, swallowing difficulties, and a loss of a sense of taste, and markedly impairs quality of life after 131 I therapy (19)(20)(21). Thus, the prevention of salivary gland dysfunction by 131 I is clinically important and methods to prevent this dysfunction are urgently required.…”