SAN DIEGO — Patients with stage I thyroid cancer who have a negative first follow-up test performed within 1 year after iodine-131 ablation have a low risk of recurrence and do not require further thyroid stimulation tests, results from a single-center French study showed.
“Some authors suggest periodic testing [with] recombinant human thyroid-stimulating hormone [rhTSH] in all thyroid cancer patients, but there is no consensus” on the issue, Dr. Paolo Zanotti-Fregonara said at the annual meeting of the Society of Nuclear Medicine. “Follow-up recommendations are likely to have economic consequences.”
He and his associates evaluated 129 thyroid cancer patients referred to the department of nuclear medicine at Saint Antoine University Hospital, Paris, between 2002 and 2004 for rhTSH testing. They classified the patients into three groups based on the International Union Against Cancer TNM (primary tumor, regional lymph nodes, distant metastasis) risk classification and the results of their first control test.
All patients had undergone a first control test after thyroxine withdrawal within 1 year of
Of the 129 patients, 75 had stage I thyroid cancer and a negative first control (group 1), 19 had stage I disease and a positive first control (group 2), and 35 had stage II-IV disease (group 3). The researchers performed rhTSH testing an average of 6 years after the first control test.
Dr. Zanotti-Fregonara reported that diagnostic scanning after rhTSH was negative in all patients in group 1. Only one patient in this group had detectable thyroglobulin after rhTSH injection. However, this patient's level of thyroglobulin at baseline was the same as that after stimulation. Therefore, it was considered a false-positive result, probably due to antibody interference.
Seven patients in group 2 had residual thyroglobulin and two had residual
He concluded rhTSH testing is not necessary in stage I thyroid cancer patients who have a negative first follow-up test 1 year after