Objective: The objective of this study was to determine the sensitivity, specificity, and predictive value of 18-fluorodeoxyglucose positron emission tomography (PET) in predicting residual cervical metastatic disease in patients with N-positive necks undergoing curative radiotherapy and chemoradiotherapy for squamous cell carcinoma (SCC) of the upper aerodigestive tract.
Methods: The authors studied a prospective case series of patients (2003-2005) of patients undergoing radiotherapy and chemoradiotherapy for advanced head and neck SSC. Study entry criteria included N-positive neck disease, a complete response to treatment at the primary tumor site, posttreatment PET scan (8-12 weeks after completion of treatment), followed by salvage neck dissection. The posttreatment PET scan neck findings were correlated to the salvage neck dissection pathology report. The sensitivity, specificity, and predictive values of the PET scan to predict residual cervical metastatic disease after curative chemoradiotherapy were calculated.
Results: Twenty-one neck dissections (pretreatment N1 = 5, N2a = 2, N2b = 8, N3 = 6) were entered into the protocol. Four (19.0%) of the 21 neck specimens were positive for residual cervical metastatic disease, whereas the remaining 17 (80.9%) specimens demonstrated no residual carcinoma. The overall sensitivity and specificity were 75.0% and 64.7%, respectively. The positive predictive value was 33% and the negative predictive value was 91.7%.
Conclusions: Although the role of posttreatment neck dissection remains controversial, the surgeon must rely on clinical examination and imaging studies. Our practice has been to perform planned staged neck dissections on all N2 and N3 necks, as well as N1 necks with an incomplete response to treatment. Based on this small prospective study, it appears that PET imaging lacks adequate sensitivity and specificity to reliably predict the presence of residual cervical metastatic disease after completion of chemoradiotherapy. With a negative predictive value of 91.7%, however, a negative PET scan appears to be a reliable predictor of the absence of residual tumor.