Sialadenitis after radioiodine therapy. Analysis of factors that influence the response to medical treatment.

OBJECTIVES To assess the incidence of 131I-induced sialadenitis (SD) in patients with differentiated thyroid cancer (DTC), to analyze clinical and other factors related to metabolic radiotherapy that may predict the lack of response to conventional medical therapy (CMT), and to determine the effectiveness of intraductal steroid instillation in patients failing CMT. MATERIAL AND METHODS Fifty-two patients with DTC, 45 females (86.5%) and 7 males (13.5%) with a mean age of 44.21±13.3 years (r=17-74) who received ablation therapy with 131I after total thyroidectomy. Patients with diseases and/or medication causing xerostomia were excluded. Patients underwent salivary gland scintigraphy with 99Tc (10mCi). RESULTS Eighteen patients (34.62%) had SD and received antibiotics, antispasmodics, and oral steroids for 15 days. They were divided into two groups: responders to medical therapy (n=12, age 44.3±14.4 years, 2 men [17%], 10 women [83%], cumulative dose 225±167.1 mCi) and non-responders to medical treatment, who underwent steroid instillation into the Stensen's duct (n=6 [33%], 2 men [33%], 4 women [67%], age 50±13.8 years, cumulative dose 138.3±61.7 mCi). Scintigraphy showed damage to the parotid and submaxillary glands. CONCLUSION Incidence of 131I-induced sialadenitis was similar to that reported by other authors. Age, mean cumulative dose of 131I, and involvement of parotid and submaxillary glands did not condition response to CMT; however, male sex was a conditioning factor. Symptom persistence for more than 15 days makes instillation into the Stensen's duct advisable. This is an effective and safe method to avoid surgical excision of salivary glands.