PET Scans Read Normal but Patient Dies From Metastatic Disease

This case involves a fifty-nine-year-old male with a history of a goiter on the right side of his neck that was removed in 2010. A follow-up biopsy was performed that revealed suspicious tissue and the patient was advised to have his left thyroid removed as a precaution. Two PET Scans were done after both surgeries with the first scan being read as suspicious and the second being read as normal. The patient initially had PET scans done every six months and then tests were recommended yearly. He was told all PET Scans were normal. One year after his last scan, the patient was working in his yard, and he felt a tear and pop in his left shoulder. He went to the emergency room where additional diagnostic scans were performed. The patient was told he had bone destruction and deterioration from a cancerous metastatic disease that was detected in his ribs and vertebrae.

Question(s) For Expert Witness

1. What is the normal follow-up protocol in detecting the recurrence or metastasis of thyroid cancer?

Expert Witness Response E-000348

Patients are regularly monitored every six to twelve months with serial radioiodine scanning and serum thyroglobulin measurements after surgery and radioiodine therapy. Thyroglobulin is a useful marker of tumor recurrence because well-differentiated thyroid cancers synthesize thyroglobulin. It is only useful, however, after total thyroid ablation. Serum thyroglobulin is measured at the time of follow-up thyroid scanning, during the withdrawal of thyroid hormone, or the administration of recombinant TSH. Serum antithyroglobulin antibodies are measured in addition to thyroglobulin because their presence invalidates the assay. Thyroglobulin antibody levels should be obtained with each thyroglobulin measurement. Rising thyroglobulin levels after thyroid ablation suggests recurrence. Ultrasonography of the neck can also be used to detect regional recurrences.