Thyroglobulin antibody levels do not predict disease status in papillary thyroid cancer.
BACKGROUND
Thyroglobulin antibodies (TgAb) are present in approximately 20% of patients with papillary thyroid cancer (PTC) and invalidate the serum thyroglobulin (Tg) level as a tumour marker. We examined whether trends in the TgAb level could serve as a surrogate marker of disease status in the surveillance of patients with PTC.


METHODS
All patients found to have a least one positive postoperative TgAb level (determined by the Beckman-Coulter Access Assay) after undergoing initial surgery for PTC from 2000 to 2010 at a single institution were included. Log-log transformation and linear regression were applied to longitudinal TgAb levels, yielding patient-specific regression coefficients that categorized as follows: highly negative, moderately negative and positive/no trend. The recurrence rate in each category was then assessed.


RESULTS
Ninety-three of 967 patients with PTC were included. Recurrent disease was detected in 19 patients (20%) after a mean follow-up time of 51 months. Regression coefficients in the highly negative and moderately negative groups were not different, and hence these groups were pooled. The proportion of recurrent cases in the negative trend group was similar to that in the positive/no trend group (19.7% vs 21.9%, NS). The mean regression coefficients were similar for recurrent and nonrecurrent cases within both the negative trend group (-0.89 vs -0.80, NS) and the positive/no trend group (0.08 vs 0.33, NS).


CONCLUSIONS
Trends in the TgAb level do not predict disease status in PTC in our experience. In the context of most commercially available TgAb assays, surveillance of TgAb-positive patients will hinge on high-quality imaging until a valid alternative serum marker to Tg is identified.
Division of Endocrinology, UCLA David Geffen School of Medicine, Los Angeles, CA, USA.
Stephanie
S
Smooke-Praw
Kevin
K
Ro
Olga
O
Levin
Philip H G
PH
Ituarte
Avital
A
Harari
Michael W
MW
Yeh
D000328:Adult; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D014408:Biomarkers, Tumor / Q000097:blood; D002277:Carcinoma / Q000097:blood* / Q000378:metabolism / Q000473:pathology; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000378:metabolism; D013954:Thyroglobulin / Q000097:blood* / Q000276:immunology; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000097:blood* / Q000378:metabolism / Q000473:pathology
D001323:Autoantibodies; D014408:Biomarkers, Tumor; C006606:anti-thyroglobulin; D013954:Thyroglobulin