rhTSH Stimulated FDG-PET/CT in Selected DTC Patients with Slightly Elevated Thyroglobulin Enables to Optimize the Treatment Efficacy

Program: Abstracts - Orals, Poster Previews, and Posters
Session: SAT 270-310-Thyroid Neoplasia (posters)
Saturday, April 2, 2016: 1:15 PM-3:15 PM
Exhibit/Poster Hall (BCEC)

Poster Board SAT 301
Alicja Hubalewska-Dydejczyk1, Monika Buziak-Bereza1, Malgorzata Trofimiuk-Muldner*2, Agata Baldys-Waligorska2, Anna Sowa-Staszczak3 and Maciej Kolodziej4
1Jagiellonian University Medical College, Krakow, Poland, 2Jagiellonian University Medical College, Faculty of Medicine, Krakow, Poland, 3Jagielloniak University Medical College, Faculty of Medicine, Krakow, Poland, 4University Hospital in Krakow, Krakow, Poland
Basal and rhTSH stimulated serum thyroglobulin (Tg) are the main markers of successful DTC patients treatment.  However, the management of DTC patients with slightly elevated serum Tg after thyroidectomy and 131I treatment still remains a clinical challenge. Recurrent/persistent tumor is rarely found in early stages. rhTSH stimulated FDG-PET/CT seems to be helpful in such cases in tumor detection however the literature data is sparse. Tg measurement always needs to be repeated to confirm its actual increase.

Material and methods:

Five patients, aged 56.6 ±9.6 (45 – 70) years, who were initially successfully treated with surgery and radioiodine, were qualified to the FDG-PET/CT after rhTSH administration due to suspicion of the DTC recurrence. Three out of 5 patients suffered from follicular cancer, in 2 subjects follicular variant of papillary cancer was diagnosed (TNM staging: pT1b N0Mx to pT3 N0Mx). All patients had the repeated slightly elevated Tg levels and  negative results of both 131I post therapeutic scans and unstimulated FDG-PET/CT scans. Maximal values of  l-thyroxin suppressed and rhTSH stimulated Tg  were 12.9 ±7.8 ng/ml and 52.7±16.3 ng/ml respectively; a-Tg antibodies were negative in each case.

Results: rhTSH stimulated FDG-PET/CT scans were positive in 4 out of 5 patients.

rhTSH FDG-PET/CT result influenced further patients management as follows: patient 1 (female): 2 bone metastases were detected and successfully treated with external beam, remission; patient 2 (female): single pulmonary meta (9/10 lung segment) was found and  confirmed histopathologically; patient 3 (male): 4 mm focal FDG uptake in FTC recurrence in the neck fascia was detected and removed; patient 4 (female): focal tracer uptake in the neck region was found, due to contraindication to surgery and increasing thyroglobulin levels thyroid inhibitor treatment was applied; patient 5 (male): negative scan, the decrease of Tg level was observed.  

Conclusions: rhTSH administration improves the sensitivity of FDG-PET/CT in selected DTC patients enabling to optimize the treatment with a more effective strategy. Further studies should be undertaken to validate the clinical usefulness of this procedure.

Nothing to Disclose: AH, MB, MT, AB, AS, MK

*Please take note of The Endocrine Society's News Embargo Policy at https://www.endocrine.org/news-room/endo-annual-meeting/pr-resources-for-endo