title: V30 as a predictor for radiation-induced hypothyroidism: a dosimetric analysis in patients who received radiotherapy to the neck.
abstract: BACKGROUND
  The purpose of this study is to evaluate the possible predictors of thyroid disorders after neck radiotherapy, with a focus on radiation dose-volume factors.
  
  
  METHODS
  Thyroid function was measured in 100 patients who had received radiotherapy to the neck, including the thyroid. All radiation-induced thyroid dysfunctions were determined with an endpoint of abnormal thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and thyroxine (fT4) and thyroid peroxidase antibodies and (TPA). The total volume of the thyroid, mean radiation dose to the thyroid (Dmean) and thyroid volume percentage that received radiation doses of 10-50 Gy (V10-V50) were calculated in all patients. The evaluated risk factors for thyroid dysfunction included dose-volume parameters, sex, age, previous surgery, chemotherapy and comorbidity.
  
  
  RESULTS
  There were 52 patients with hypothyroidism and V30 (p = 0.03), thyroid volume (p = 0.01) and Dmean (p = 0.03) appeared to be correlated with hypothyroidism in univariate analysis. However, there was not association found in multivariate analysis for these factors.
  
  
  CONCLUSIONS
  Thyroid disorders after radiation therapy to the neck still represent a clinically underestimated problem. V30 may be a useful tool for evaluating the risk of hypothyroidism when determining an individual patient's treatment.
authors.affiliation: Department of Radiation Oncology, Bezmi Alem Vakif University Medical School, Adnan Menderes Bulvari, 34093 Istanbul, Fatih, Turkey. zuleyhaakgun@gmail.com.
authors.forename: Zuleyha
authors.initials: Z
authors.lastname: Akgun
authors.forename: Beste M
authors.initials: BM
authors.lastname: Atasoy
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Ozen
authors.forename: Dilek
authors.initials: D
authors.lastname: Yavuz
authors.forename: Bahadir
authors.initials: B
authors.lastname: Gulluoglu
authors.forename: Meric
authors.initials: M
authors.lastname: Sengoz
authors.forename: Ufuk
authors.initials: U
authors.lastname: Abacioglu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis*; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000150:complications* / Q000532:radiotherapy*; D006801:Humans; D007037:Hypothyroidism / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011832:Radiation Injuries / Q000175:diagnosis* / Q000209:etiology; D011878:Radiotherapy / Q000009:adverse effects*; D013960:Thyroid Function Tests; D055815:Young Adult
chemical_list: D015415:Biomarkers