title: Positive predictive value of detectable stimulated tg during the first year after therapy of thyroid cancer and the value of comparison with Tg-ablation and Tg measured after 24 months.
abstract: This study evaluated the positive predictive value (PPV) of detectable stimulated thyroglobulin during the first year after treatment of thyroid carcinoma (Tg-1) and the value of comparison with Tg-ablation and measured after 24 months (Tg-2). Forty-two consecutive patients undergoing total thyroidectomy and ablation with detectable Tg-1 (>1ng/mL) were selected. The patients had well-differentiated tumors, which were completely resected, and there was no ectopic uptake on whole body scan after 3.7-5.5GBq I(131). Imaging methods during follow-up revealed metastases in 10 patients (24%) (15% if Tg-1 <or=10 ng/mL and 55% if Tg-1 >10 ng=mL). Tg-ablation (cutoff of 10 ng/mL) presented a negative predictive value (NPV) of 91% and PPV of 42%. Comparing Tg-ablation with Tg-1, the PPV of an increase was 100%, whereas the NPV of a decrease was 88%. Thirty-six patients presented negative imaging results upon first assessment and Tg-1 was compared to Tg-2. Metastases were detected in all patients who presented an increase in Tg (n=4), whereas patients without variation (n=4) or with a decrease (n=28) showed no apparent disease. Among disease-free patients (n=32), 50% presented undetectable Tg and 40% showed a >50% decrease after 2 years. In conclusion, most patients with detectable stimulated Tg during the first year after therapy had no metastases, and evaluation of the slope of Tg helped discriminate cases with apparent disease.
authors.affiliation: Department of Thyroid, Endocrinology Service, Santa Casa de Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Maristane M A
authors.initials: MM
authors.lastname: Valadão
authors.forename: Pedro W S
authors.initials: PW
authors.lastname: Rosário
authors.forename: Michelle A R
authors.initials: MA
authors.lastname: Borges
authors.forename: Graciela B C
authors.initials: GB
authors.lastname: Costa
authors.forename: Leonardo L
authors.initials: LL
authors.lastname: Rezende
authors.forename: Eduardo L
authors.initials: EL
authors.lastname: Padrão
authors.forename: Alvaro L
authors.initials: AL
authors.lastname: Barroso
authors.forename: Saulo
authors.initials: S
authors.lastname: Purisch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002648:Child; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000532:radiotherapy* / Q000556:secondary / Q000601:surgery*; D013965:Thyroidectomy; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood
chemical_list: D015415:Biomarkers; D007457:Iodine Radioisotopes; D013972:Thyrotropin; D013954:Thyroglobulin; D013974:Thyroxine