Detection of Thyrotropin-Receptor Messenger Ribonucleic Acid (mRNA) and Thyroglobulin mRNA Transcripts in Peripheral Blood of Patients with Thyroid Disease: Sensitive and Specific Markers for Thyroid Cancer

Abstract

Because thyroid cancer cells express functional TSH receptors (TSHR), TSHR-mRNA in peripheral blood might serve as a tissue-/cancer-specific marker. We measured circulating TSHR-mRNA by RT-PCR in 51 normal controls, 27 patients with benign thyroid disease, 67 patients with treated differentiated thyroid cancer (DTC), and eight patients with newly diagnosed DTC, preoperatively. Results were compared with thyroglobulin (Tg) mRNA and serum Tg levels. TSHR-mRNA signals were not detected in normal controls and in 24 of 27 (89%) patients with benign thyroid disease. All 19 patients with treated DTC with evidence of distant or local disease tested positive for TSHR-mRNA (sensitivity 100%). Among patients with no evidence of disease, TSHR-mRNA was detected in 1 in 48 (specificity 98%). Six of the eight newly diagnosed DTC patients tested preoperatively were positive for TSHR-mRNA. The concordance between TSHR-mRNA and Tg-mRNA and between TSHR-mRNA and serum Tg was 95%. Fourteen patients with DTC (21%) had Tg antibodies, three with local disease (all positive for TSHR-mRNA), and 11 with no evidence of disease (all negative for TSHR-mRNA). Our results indicate that TSHR-mRNA and/or Tg-mRNA in peripheral blood are both equally sensitive and specific markers for monitoring thyroid cancer patients. Their principal value resides in the Tg antibody-positive patients in whom a positive or a negative mRNA value might have indicated or obviated the need for a whole-body scan. Furthermore, the high specificity combined with their ability to predict thyroid cancer preoperatively suggests a potential role in detecting thyroid cancer in patients with thyroid nodules.

Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Taskforce

“…Decreasing antibody levels are correlated with "disease-free" status while increasing levels suggest persistent disease (199,296). Measurement of thyroglobulin mRNA in the blood may be a sensitive marker for persistent thyroid cells even in the presence of anti-thyroglobulin antibodies (297)(298)(299), but RNA extraction is not well standardized and some studies question the specificity of this marker (300,301). Future studies optimizing thyroglobulin mRNA measurements in blood from DTC patients with antithyroglobulin antibodies, further development of thyroglobulin assays that have limited interference by antithyroglobulin antibodies or methods to clear antithyroglobulin antibodies prior to thyroglobulin measurement are needed to better monitor this challenging subgroup of patients with DTC.…”

Oncofoetal fibronectin – a tumour-specific marker in detecting minimal residual disease in differentiated thyroid carcinoma

“…A recently published review concluded that Tg mRNA measurement is an invalid approach in the postoperative care of patients with DTC due to illegitimate expression of this marker in peripheral blood cells, although RT-PCR concepts in general are worthy of further investigations (Verburg et al, 2004). However, two other studies demonstrated results opposite to the conclusions drawn in this review, and reported a high specificity of Tg or TSH-R mRNA for thyroid cancer, hence promoting their application in DTC detection (Chinnappa et al, 2004;Li et al, 2004). Therefore, the experimental usefulness of Tg transcripts and the potential clinical relevance of this marker are still under debate.…”

“…Despite improved therapy concepts and excellent prognosis, tumour relapse and metastases do occur in 10% of patients (Mazzaferri, 2000). Thus, over the last decade, many studies have attempted to improve DTC diagnosis and patient follow-up using RT -PCR-based approaches in order to track down circulating tumour cells (Ditkoff et al, 1996;Tallini et al, 1998;Ringel et al, 1999;Wingo et al, 1999;Biscolla et al, 2000;Bojunga et al, 2000;Weber et al, 2000;Bugalho et al, 2001;Takano et al, 2001;Eszlinger et al, 2002;Span et al, 2003;Chinnappa et al, 2004;Elisei et al, 2004;Li et al, 2004).…”

Development, characterization and clinical validation of new sensitive immunofluorometric assay for the measurement of serum thyroglobulin

“…Having continuous access to the same methodology, we will be able to study alternatives in order to deal with the interference of these antibodies in our assay. Until now, to prevent interference by TgAb, we and others have developed qualitative RT-PCR assay to amplify mRNA Tg present in circulating thyroid cells from patients with DT, allowing differentiation between patients "free of disease" and those with metastases (34,35). Therefore, mRNA Tg could be an appropriate molecular marker for the follow-up of patients with thyroid carcinoma, especially in patients with positive TgAb.…”