Dosimetric analysis for thyroid disorders after radiotherapy to the neck


Akgun Z., Atasoy B., Ozen Z., Gulluoglu B., Abacioglu M. U.

JOURNAL OF CLINICAL ONCOLOGY, cilt.27, sa.15_suppl, ss.17025, 2009 (SCI-Expanded)

  • Yayın Türü: Makale / Özet
  • Cilt numarası: 27 Sayı: 15_suppl
  • Basım Tarihi: 2009
  • Doi Numarası: 10.1200/jco.2009.27.15_suppl.e17025
  • Dergi Adı: JOURNAL OF CLINICAL ONCOLOGY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.17025
  • Acıbadem Mehmet Ali Aydınlar Üniversitesi Adresli: Hayır

Özet

e17025 Background: In our study, we aimed to evaluate the possible predictors of thyroid disorders after radiotherapy to the neck, focusing on radiation dose-volume factors. Methods: Thyroid function was measured in 65 patients treated with radiation ports including the thyroid, between 2005 and 2008. All of the radiation-induced thyroid dysfunction was determined with an endpoint of abnormal thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and thyroxine (fT4), thyroglobulin antibodies (ATG), thyroid peroxidase antibodies (TPA), thyroid binding globulin (TBG) levels. In 65 patients, radiation dose-volume parameters were calculated; e.g. total volume of the thyroid, mean radiation dose to the thyroid, and percentage of the thyroid volume which received radiation doses of no less than 10–50 Gy (V10-V50). The evaluated risk factors for thyroid dysfunction included these dose-volume parameters, sex, age, treatment modality and primary disease. Results: Most patients (72.3%) had a normal thyroid function, 17 (26.2%) hypothyroidism, 1 (1.5%) hyperthyroidism, and 12 (18.4%) thyroiditis with normal thyroid function. Four of 17 patients with hypothyroidism had overt hypothyroidism. In our analysis, DVHs (dose volume histograms) were calculated and no associations were found between the V10, V20, V40, and V50 percentages and thyroid disorders. V30 and minimum absorbed thyroid dose (Dmin) more than 25 Gy appeared to be correlated with high TSH values (p = 0.01 and p = 0.04, respectively). The patients with hypothyroidism were between 40–60 years. Female gender was associated with a higher incidence of TBG abnormality. Baseline TSH values were available in 16 patients, and hypothyroidism was diagnosed in 4 (25%) of them. No correlation was found between tumor-related variables and incidence of thyroid disorders. Conclusions: Thyroid disorders after radiation therapy to the neck still represent a clinically underestimated problem. Further prospective well designed studies on dose-effect relationship for radiotherapy-induced thyroid toxicity are therefore needed, and thyroid should be considered as an organ at risk in all patients treated for head and neck tumors. No significant financial relationships to disclose.