FDG-PET Detects Thyroid Cancer Better Than Conventional Imaging

OncologyONCOLOGY Vol 15 No 12
Volume 15
Issue 12

Fluorodeoxyglucose positron-emission tomography (FDG-PET) detected recurrent cancer 50% more often than did conventional imaging in people with thyroid cancer who had indications that their cancer had recurred, according to results of

Fluorodeoxyglucose positron-emission tomography (FDG-PET)detected recurrent cancer 50% more often than did conventional imaging in peoplewith thyroid cancer who had indications that their cancer had recurred,according to results of a study published in the October 2001 issue of the Journal of Nuclear Medicine. Indeed, use of the FDG-PET scan led to changes inclinical management in almost 80% of patients.

The study evaluated 37 persons with differentiated thyroid carcinoma, who hadelevated levels of thyroglobulin and negative iodine-131 (I-131) whole-body scanresults after a thyroidectomy and radioactive iodine treatment. An elevatedhuman thyroglobulin (hTg) level is a strong indicator that the cancer persistsor has recurred.

Some patients with metastases do not concentrate I-131, and there areindications that they are more likely to have aggressive disease. Finding a wayto locate tumors when evidence suggests recurrence but I-131 scan results arenegative is, therefore, particularly important.

PET Uncovers Additional Sites of Disease

Of the 37 patients who underwent FDG-PET scanning, 28 (76%) had positivefindings. Conventional imaging of the same patients (ultrasound, magneticresonance imaging [MRI], computed tomography [CT], and x-ray) produced positiveresults in only 10 cases (27%). Among the 10 patients in whom conventionalimaging did not detect a tumor, FDG-PET detected an additional 11 sites ofdisease, including distant metastases in 5 patients. Among those whose cancerwas only detected by the PET scan, 44 different tumor sites were detected.

Overall, the FDG-PET scan findings changed the management of 29 patients; 23underwent surgery, and disease was confirmed in 20. In three patients, pathologydetermined that the high FDG uptake was the result of inflammatory disease, foran overall true-positive rate of 70%.

"Our study shows that PET detects significantly more disease thanconventional images for these cancer patients. We believe that a PET scan shouldbe added as a first-line investigative tool to look for disease when there is anegative I-131 posttherapy scan yet the patient’s thyroglobulin levels arehigh," said study coauthor Dr. Badia O. Helal, Hôpital Antoine Béclère,Clamart, France.

Related Videos
The use of a single-port robot may allow for surgically treating more patients with head and neck cancer in a more timely manner, according to Hilary McCrary, MD, MPH.
Treatment with toripalimab does not yield the same vascular toxicity seen with pembrolizumab in patients with advanced or metastatic nasopharyngeal carcinoma, according to Barbara Burtness, MD.
Overall survival also appears to improve with toripalimab compared with chemotherapy among patients with metastatic or advanced nasopharyngeal carcinoma.
Eric J. Sherman, MD, highlights several drugs that are being used to treat RET-positive thyroid cancer.