Context: The BRAFT1799A transversion is the most frequent morphotype-specific somatic mutation in papillary thyroid carcinoma (PTC). The ability to detect this mutation in the circulation could aid in diagnosis and follow-up of PTC patients. Objective: Our objective was to develop and clinically validate a sensitive and specific assay for the detection of BRAFT1799A in blood samples from PTC patients. Design: We developed an allele-specific real-time PCR method for the detection of BRAF T1799A in blood samples and studied prospectively blood samples from 193 patients with thyroid cancer (173 PTC, 20 non-PTC) attending for routine follow-up. The results of molecular testing were correlated with disease status and thyroglobulin measurements. BRAFT1799A status of the original tumor samples was also confirmed, where available. Results: The assay had a detection sensitivity of fewer than one heterozygote BRAFT1799A- carrying cell per 100,000 diploid cells, without detectable cross-reactivity between wild-type BRAF and BRAFT1799A. Circulating BRAF T1799A was detected in 20 of 173 PTC patients and in none of the 20 non-PTC patients. BRAFT1799A-positive samples contained between one in 326 and fewer than one in 100,000 copies of BRAFT1799A. Tissue BRAF status correlated with blood BRAF status, whereas BRAFT1799A positivity in blood correlated with the presence of active disease at the time of the blood draw, with eight of the 38 PTC patients with persistent/recurrent disease being positive for circulating BRAFT1799A (relative risk vs. circulating BRAFT1799A-negative, 2.55; P < 0.04). Conclusions: BRAFT1799A can be detected in the blood of PTC patients with residual or metastatic disease and may provide diagnostic information.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical