title: Salivary gland function 5 years after radioactive iodine ablation in patients with differentiated thyroid cancer: direct comparison of pre- and postablation scintigraphies and their relation to xerostomia symptoms.
abstract: BACKGROUND
  Chronic sialadenitis is one of the most frequent chronic complications after radioactive iodine (RAI) therapy for thyroid cancer. To evaluate the long-term effects of RAI ablation on salivary gland function, we investigated scintigraphic changes in salivary glands by direct comparison of two salivary gland scintigraphies (SGSs) taken before and at 5 years after an RAI ablation.
  
  
  METHODS
  SGS was performed just before RAI ablation (pre-SGS) and ∼5 years after RAI ablation (F/U SGS) in 213 subjects who underwent thyroidectomy for thyroid cancer. The uptake score (U score) was graded, and the ejection fraction (EF) was quantified for the parotid and submandibular glands at pre-SGS and F/U SGS. Changes in salivary gland function were graded as mild, moderate, or severe according to the differences in U score and EF between the two SGSs. Xerostomia was assessed and compared with the SGS findings.
  
  
  RESULTS
  Worsening of the U score was observed in 182 of 852 salivary glands (total: 21.3%; mild: 4.2%, moderate: 7.4%, severe: 9.7%), and 47.4% of the patients had a worsening U score for at least one of four salivary glands. A decrease in EF was observed in 173 of 852 salivary glands (total: 20.3%; mild: 5.4%, moderate: 6.8%, severe: 8.1%), and 43.7% of the patients experienced a decrease in the EF of at least one of the four salivary glands. Bilateral parotid gland dysfunction was the most commonly observed condition. Thirty-five (16.4%) patients complained of xerostomia at 5 years after RAI ablation. Scintigraphic changes in salivary gland function and xerostomia were more common in patients receiving 5.55 GBq, compared with 3.7 GBq. Xerostomia was more common in patients with submandibular gland dysfunction than those with parotid gland dysfunction (68.8% vs. 33.3%, p<0.05). The number of dysfunctional salivary glands was correlated with xerostomia (p<0.01).
  
  
  CONCLUSIONS
  About 20% of the salivary glands were dysfunctional on SGS 5 years after a single RAI ablation, especially in patients who received higher doses of RAI. While parotid glands are more susceptible to (131)I-related damage, xerostomia was more associated with submandibular gland dysfunction and the prevalence of dysfunctional salivary glands.
authors.affiliation: Department of Nuclear Medicine, Kyungpook National University School of Medicine/Hospital , Daegu, Korea.
authors.forename: Shin Young
authors.initials: SY
authors.lastname: Jeong
authors.forename: Hae Won
authors.initials: HW
authors.lastname: Kim
authors.forename: Sang-Woo
authors.initials: SW
authors.lastname: Lee
authors.forename: Byeong-Cheol
authors.initials: BC
authors.lastname: Ahn
authors.forename: Jaetae
authors.initials: J
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy / Q000009:adverse effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D056910:Republic of Korea / Q000453:epidemiology; D012469:Salivary Glands / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology* / Q000528:radiation effects; D012720:Severity of Illness Index; D012793:Sialadenitis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D013363:Submandibular Gland / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology / Q000528:radiation effects; D013364:Submandibular Gland Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D013964:Thyroid Neoplasms / Q000503:physiopathology / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy; D014987:Xerostomia / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals