Circulating thyroglobulin mRNA does not predict early and midterm recurrences in patients undergoing thyroidectomy for cancer

BACKGROUND: The aim of the present study was to evaluate if serum Tg mRNA assay predicts recurrence in patients undergoing thyroidectomy for cancer. METHODS: Sixty-four consecutive patients undergoing surgery between April 1997 and July 1999 were studied. One year after surgery, blood samples were taken for serum thyroglobulin (Tg) immunoassay and for Tg mRNA assay by reverse transcription-polymerase chain reaction (RT-PCR). All patients underwent periodical clinical examination, including laboratory tests for serum Tg immunoassay, neck ultrasound, radioiodine scans, and treatment if indicated. Kaplan-Meier estimates of survival were calculated according to the presence or absence of circulating Tg mRNA and according to baseline Tg levels. RESULTS: Tg mRNA was detected in 14 (21.8%) of 64 patients with thyroid carcinoma. After a median follow-up of 110 months, 8 patients (12.5%) relapsed. Among patients with detectable Tg mRNA (n. 14), only 1 distant metastasis occurred (7%), whereas lymph node metastases (n = 3) or distant metastases (n = 4) were detected in 7 of 50 patients (14%) with undetectable Tg mRNA. Tumor relapse occurred in all 7 patients with increased serum Tg and only in 1 out of 57 patients (1.7%) with normal or undetectable serum Tg. The disease-free interval of patients positive at baseline for Tg mRNA was similar to that of patients with undetectable Tg mRNA at baseline. Similar results were obtained when we limited the analysis to only patients who received postsurgical radioiodine ablation. CONCLUSIONS: The results of present study suggest that detection of circulating Tg mRNA 1 year after thyroidectomy for cancer might be of no utility in predicting early and midterm local and distant recurrences.