(68)Ga-DOTA-peptide: A novel molecular biomarker for nasopharyngeal carcinoma.
BACKGROUND
Increased somatostatin receptor (SSTR) expression in patients with undifferentiated nasopharyngeal carcinoma (NPC) has been demonstrated with receptor autoradiography, (111) In-Octreotide scintigraphy, and (68) Ga-DOTA-TOC positron emission tomography (PET)/CT imaging. We sought to compare and correlate the uptake of fluorodeoxyglucose (FDG) and DOTA-NOC in undifferentiated NPC to ascertain the possible role of (68) Ga-DOTA-NOC PET/CT as a new imaging biomarker and to assess whether targeted peptide receptor radionuclide therapy is a feasible treatment option.


METHODS
After obtaining approval from our institutional review board, 4 patients with biopsy proven nonkeratinizing undifferentiated NPC who had just undergone routine staging/restaging (18) F-FDG PET/CT imaging were prospectively and consecutively recruited for (68) Ga-DOTA-NOC PET/CT imaging. Of these 4 patients, 3 were newly diagnosed with untreated NPC, whereas 1 patient was diagnosed with a case of recurrent NPC with previous treatment. These patients subsequently underwent (68) Ga-DOTA-NOC PET/CT within 10 days from the (18) F-FDG PET/CT to ensure lesion comparability. Tracer uptake in tumor lesions were assessed visually and semiquantitatively by measuring maximum standardized uptake values (SUVmax).


RESULTS
There were 12 FDG-avid lesions of which 7 showed avid uptake of DOTA-NOC greater than liver uptake, whereas 5 showed low uptake of DOTA-NOC less than liver uptake. Subset analysis of the FDG-avid lesions at the primary and recurrent sites showed that all the FDG-avid primary tumors in the nasopharynx showed avid uptake of DOTA-NOC. On the contrary, the case of recurrent NPC showed avid FDG uptake but low DOTA-NOC uptake. Subset analysis of the suspicious FDG-avid cervical lymph nodes showed that 50% of them demonstrated avid DOTA-NOC uptake greater than liver uptake, whereas the remaining demonstrated low-grade DOTA-NOC uptake less than liver uptake. The 2 subcentimeter cervical lymph nodes that showed low-grade uptake of FDG lower than mediastinal blood pool activity were deemed to be reactive/inflammatory and showed low-grade uptake of DOTA-NOC.


CONCLUSIONS
This study highlights the potential of (68) Ga-DOTA-peptide PET/CT as a new molecular biomarker for newly diagnosed undifferentiated NPC, and less so for recurrent NPC and metastatic nodes. This potentially opens up new diagnostic and therapeutic options in the management of undifferentiated NPC.
Department of Diagnostic Imaging, National University Hospital, Singapore.
Lih Kin
LK
Khor
Department of Diagnostic Imaging, National University Hospital, Singapore.
Hoi Yin
HY
Loi
Department of Diagnostic Imaging, National University Hospital, Singapore.
Arvind Kumar
AK
Sinha
Department of Nuclear Medicine and PET, Singapore General Hospital, Singapore.
Kian Ti
KT
Tong
Department of Hematology and Oncology, National University Hospital, Singapore.
Boon Cher
BC
Goh
Department of Otolaryngology, National University Hospital, Singapore.
Kwok Seng
KS
Loh
Nuclear Medicine and PET Centre, Mount Elizabeth Hospital, Singapore.
Suat-Jin
SJ
Lu
D000328:Adult; D000368:Aged; D015415:Biomarkers; D014408:Biomarkers, Tumor / Q000008:administration & dosage*; D002277:Carcinoma; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging*; D009364:Neoplasm Recurrence, Local; D009942:Organometallic Compounds / Q000008:administration & dosage*; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011446:Prospective Studies; D017481:Receptors, Somatostatin / Q000378:metabolism*
C504894:68Ga-DOTANOC; D015415:Biomarkers; D014408:Biomarkers, Tumor; D009942:Organometallic Compounds; D017481:Receptors, Somatostatin; D019788:Fluorodeoxyglucose F18
18FDG positron emission tomography (PET)/CT; 68Ga-DOTA-peptide; nasopharyngeal carcinoma; somatostatin receptors