Thyroid Cancer Follow-up
After treatment, physicians will schedule routine follow-up visits and depending on the type of the cancer, may use blood tests to monitor serial serum thyroglobulin levels. Doctors may also order follow-up imaging tests such as radioactive whole-body scintigraphy to make sure the cancer has not returned.
Functional imaging studies such as PET/CT may be recommended for patients where the results of radioactive whole-body scintigraphy were normal, but the patient's thyroglobulin levels are rising. This could indicate that a phenomenon called "flip flop phenomenon" has occurred, where differentiated thyroid cancer cells transform over time and lose some or all of their ability to absorb radioactive iodine. When tumors become non-iodine-avid they may be detectable by PET/CT scans which can help localize suspected recurrent disease.
It is in this role that PET/CT imaging has the greatest impact, by helping the physician determine if thyroglobulin producing, iodine-negative metastatic thyroid cancer has returned. When iodine-negative metastatic disease is detected and localized, appropriate treatment of surgical resection or external radiotherapy can be started.
If cancer does return the ability to detect and treat thyroid cancer recurrence early is critically important.
Source: Atlas of Clinical Positron Emission Tomography by Sallie F. Barrington, Michael N. Maisey and Richard R. Wahl. Oxford University Press, Inc. New York, NY. 2006.