Molecular staging using qualitative RT-PCR analysis detecting thyreoglobulin mRNA in the peripheral blood of patients with differentiated thyroid cancer after therapy

BACKGROUND: The prognostic significance of molecular staging using thyroglobulin (Tg)-based RT-PCR analysis in the peripheral blood of patients with differentiated thyroid cancer (DTC) was investigated. Herein, the specificity of molecular staging in DTC patients after thyroidectomy and 131I ablation therapy was analysed, using different specific cDNA primers in qualitative nested and classical RT-PCR protocols.

PATIENTS AND METHODS: Ninty-five patients receiving TSH suppressive therapy were included, of whom 51 were disease-free and 44 presented residual/recurrent or metastatic disease as evidenced by biochemical and/or 131I whole-body scan.

RESULTS: Our analysis detected RT-PCR products suggestive of the presence of Tg mRNA in all the blood samples tested, including healthy controls. A splice variant (350 bp) of Tg transcript (missing exon 3) was detected by nested RT-PCR in 34% of blood samples, however, without correlation to disease status.

CONCLUSION: Qualitative Tg-based molecular staging in the peripheral blood of patients with DTC shows poor specificity in assessing DTC disease status.