Risk factors for radiation-induced hypothyroidism: AnLiterature-Based Meta-Analysis.
A systematic overview and meta-analysis ofnstudies reporting data on hypothyroidism (HT) after radiationntherapy was conducted to identify risk factors for development ofnHT.
METHODS:
Published studies were identified from the PubMednand Embase databases and by hand-searching published reviews.nStudies allowing the extraction of odds ratios (OR) for HT in 1 ornmore of several candidate clinical risk groups were included. Anmeta-analysis of the OR for development of HT with or without eachnof the candidate risk factors was performed. Furthermore, studiesnallowing the extraction of radiation dose-response data werenidentified for a meta-analysis of the dose-response curve.
RESULTS:
Female gender (OR = 1.6; 95% confidence intervaln[CI], 1.3-1.9; P < .00001), surgery involving the thyroid glandn(OR = 8.3; 95% CI, 5.7-12.0; P < .00001), or other neck surgeryn(OR = 1.7; 95% CI, 1.16-2.42; P = .006) were associated with anhigher risk of HT. Caucasians were at higher risk of HT thannAfrican Americans (OR = 4.8; 95% CI, 2.8-8.5; P < .00001). Thendata showed association between lymphangiography and HT but withnevidence of publication bias. There was a radiation dose-responsenrelation with a 50% risk of HT at a dose of 45 Gy but withnconsiderable variation in the dose response between studies.nChemotherapy and age were not associated with risk of HT in thisnanalysis.
CONCLUSIONS:
Several clinical risk factors for HT werenidentified. The risk of HT increases with increasing radiationndose, but the specific radiation dose response varies between thenstudies. The most likely cause of this heterogeneity is differencesnin follow-up between studies.
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