18F-FDG PET/CT for detecting nodal metastases in patients with oral cancer staged N0 by clinical examination and CT/MRI.
(18)F-FDG PET has a high accuracy in staging head and neck cancer, but its role in patients with clinically and radiographically negative necks (N0) is less clear. In particular, the value of combined PET/CT has not been determined in this group of patients.


METHODS
In a prospective study, 31 patients with oral cancer and no evidence of lymph node metastases by clinical examination or CT/MRI underwent (18)F-FDG PET/CT before elective neck dissection. PET/CT findings were recorded by neck side (left or right) and lymph node level. PET/CT findings were compared with histopathology of dissected nodes, which was the standard of reference.


RESULTS
Elective neck dissections (26 unilateral, 5 bilateral; a total of 36 neck sides), involving 142 nodal levels, were performed. Only 13 of 765 dissected lymph nodes harbored metastases. Histopathology revealed nodal metastases in 9 of 36 neck sides and 9 of 142 nodal levels. PET was TP in 6 nodal levels (6 neck sides), false-negative in 3 levels (3 neck sides), true-negative in 127 levels (23 neck sides), and false-positive in 6 levels (4 neck sides). The 3 false-negative findings occurred in metastases smaller than 3 mm or because of inability to distinguish between primary tumor and adjacent metastasis. TP and false-positive nodes exhibited similar standardized uptakes (4.8 +/- 1.1 vs. 4.2 +/- 1.0; P = not significant). Sensitivity and specificity were 67% and 85% on the basis of neck sides and 67% and 95% on the basis of number of nodal levels, respectively. If a decision regarding the need for neck dissection had been based solely on PET/CT, 3 false-negative necks would have been undertreated, and 4 false-positive necks would have been overtreated.


CONCLUSIONS
(18)F-FDG PET/CT can identify lymph node metastases in a segment of patients with oral cancer and N0 neck. A negative test can exclude metastatic deposits with high specificity. Despite reasonably high overall accuracy, however, the clinical application of PET/CT in the N0 neck may be limited by the combination of limited sensitivity for small metastatic deposits and a relatively high number of false-positive findings. The surgical management of the N0 neck should therefore not be based on PET/CT findings alone.
Schöder
Heiko
H
Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA. schoderh@mskcc.org
Carlson
Diane L
DL
Kraus
Dennis H
DH
Stambuk
Hilda E
HE
Gönen
Mithat
M
Erdi
Yusuf E
YE
Yeung
Henry W D
HW
Huvos
Andrew G
AG
Shah
Jatin P
JP
Larson
Steven M
SM
Wong
Richard J
RJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000737:chemistry*; D006801:Humans; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy*; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D019788:Fluorodeoxyglucose F18