Serum thyroglobulin is a poor diagnostic biomarker of malignancy in follicular and Hurthle-cell neoplasms of the thyroid.
BACKGROUND
Serum thyroglobulin (Tg) is the most accurate biomarker for thyroid cancer recurrence. However, some clinicians measure preoperative Tg as a diagnostic cancer marker despite lack of supporting evidence. We examined whether Tg accurately predicts malignancy in follicular or Hürthle-cell neoplasms.


METHODS
We reviewed 366 patients who underwent thyroidectomies for follicular/Hürthle-cell neoplasms. We compared Tg in malignant versus benign tumors by univariate and receiver-operator characteristic analyses. We also examined several Tg-derived indices that normalized Tg to known confounding factors including nodule size, thyroid function, and type of Tg assay.


RESULTS
Thirty-nine patients met inclusion criteria for analysis. There were no differences between malignant (n = 16) and benign (n = 23) lesions in Tg or any of the normalized indexes. Receiver-operator characteristic analysis revealed an area under the curve of .59. Lesions with Tg levels greater than 500 mug/L had a positive predictive value of .75.


CONCLUSIONS
Tg has poor accuracy for predicting malignancy in follicular or Hürthle-cell thyroid neoplasms.
Suh
Insoo
I
Department of Surgery, University of California-San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0470, USA. insoo.suh@ucsfmedctr.org
Vriens
Menno R
MR
Guerrero
Marlon A
MA
Griffin
Ann
A
Shen
Wen T
WT
Duh
Quan-Yang
QY
Clark
Orlo H
OH
Kebebew
Electron
E
D018263:Adenocarcinoma, Follicular / Q000097:blood / Q000473:pathology* / Q000601:surgery; D018249:Adenoma, Oxyphilic / Q000097:blood / Q000473:pathology* / Q000601:surgery; D000328:Adult; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy
D015415:Biomarkers; D013954:Thyroglobulin