Role of 18F-FDG PET/CT in Guiding Surgical Management of Clinically Node Negative Neck (cN0) in Carcinoma Oral Cavity.

Abstract

Conventional staging paradigm with clinical examination or imaging invariably leads to underestimation of occult metastatic neck disease in oral cavity carcinoma. The advantage of 18F-FDG PET/CT is in its ability to identify lymph nodes without morphological changes yet harboring occult metastases. We present findings of our study to evaluate diagnostic accuracy of 18F-FDG PET/CT, in detecting occult cervical lymph node metastasis in carcinoma oral cavity. In a single institution prospective study, 51 consecutive patients with histologically proven (cT1/T2) oral cavity carcinoma and clinically node negative neck (cNo), underwent 18F-FDG PET/CT before elective neck dissection of 58 neck sides. 18F-FDG PET/CT findings were compared with histopathology of dissected nodes, to calculate diagnostic accuracy. 18F-FDG PET/CT correctly characterized the occult lymph node metastasis status (true positive + true negative) in 51 of 58 neck sides, yielding diagnostic accuracy of 87.93%. Sensitivity of 18F-FDG PET/CT was 90% and specificity was 87.5%. While a positive 18F-FDG PET/CT accurately predicted the disease in only 60% (positive predictive value), a negative 18F-FDG PET/CT reasonably ruled out occult metastases in 97.67% (negative predictive value). If a decision regarding the need for neck dissection had been based solely on 18F-FDG PET/CT, the number of neck dissections would have been reduced by 74.13%. Based on diagnostic accuracy and high negative predictive value, incorporating 18F-FDG PET/CT in preoperative staging paradigm of cT1/T2 carcinoma oral cavity will guide in selection of patients in which cN0 neck can be safely observed.