For monitoring thyroid cancer patients post-diagnosis, the current practice involves blood tests to measure serum thyroglobulin, indicating cancer recurrence or residual disease. Dr. Chih-Yuan Wang, Deputy Director of the Department of Internal Medicine at National Taiwan University Hospital (NTUH), and his research team have identified thyroglobulin in urine exosomes as a biomarker for post-operative monitoring of thyroid cancer. This non-invasive urine test can track recurrence trends with significant sensitivity and accuracy, detecting signs of recurrence five to six years earlier than traditional methods. This technique has already received an international patent.
"Before a blood test, thyroid cancer patients must receive an injection of recombinant human TSH (thyroid-stimulating hormone), costing around NT$40,000 per dose, to enhance test accuracy. Moreover, blood tests are invasive," Dr. Wang explained. Urine testing, being non-invasive, reduces patient anxiety. This method leverages exosomes in the urine to detect early changes and trends in thyroglobulin levels. Since there are no thyroglobulin antibodies in urine, detecting thyroglobulin peptide sequences becomes more accurate, unimpeded by interference.
According to the latest cancer registry report by the National Health Agency, thyroid cancer ranks seventh among the top ten cancers. In Taiwan, over 5,000 thyroid surgeries are performed annually. Dr. Wang emphasized that the rapid increase in thyroid cancer cases necessitates efficient, non-invasive, safe, and easy-to-use diagnostic and monitoring indicators in clinical practice. Urine exosomes serve as crucial prognostic markers and therapeutic targets for cancer.
Dr. Wang explained that exosomes are minuscule substances secreted by cells, measuring just 10 nanometers (one-billionth of a meter). Past cell experiments have shown that certain drugs can induce exosome changes related to patient prognosis. Using mass spectrometry, the detection of thyroid cancer recurrence via exosomes involves protein sequencing and quantification with an accuracy exceeding 99%.
NTUH has conducted clinical trials using urine tests to monitor the prognosis of numerous thyroid cancer patients. Dr. Wang shared a case where a patient, reassured by the non-invasive nature of urine testing, showed no signs of cancer recurrence in blood tests but displayed abnormalities in urine tests. Subsequent nuclear medicine examinations revealed tissues potentially leading to recurrence, prompting the medical team to adjust the follow-up and treatment plan accordingly.
Currently, this testing method has not yet been commercialized. If hospitals were to offer it as a self-pay service, the costs associated with reagents and testing would be significant. Beyond prognostic tracking, urine exosome testing could also be developed for early diagnosis. Future collaborations with the industry could help reduce patient burdens and benefit more patients.
