Detection of circulating tumor cells for prediction of recurrence after adjuvant chemoradiation in locally advanced squamous cell carcinoma of the head and neck

Background: The prognostic role of persistence of circulating tumor cells (CTC) after upfront tumor surgery for outcome of adjuvant (chemo) radiation in locally advanced squamous cell carcinoma of the head and neck (LASCCHN) was evaluated. Patients and methods: In this prospective study, peripheral blood samples from 144 patients with LASCCHN presenting after tumor resection for adjuvant treatment were analyzed for CTC. Their detection was correlated with tumor site, clinical risk factors, disease-free (DFS) and overall survival (OS). Results: CTC were detected in 42 of 144 patients (29%). CTC detection was higher in cases with nodal involvement and in carcinomas located at the tonsil or base of tongue but was not influenced by age, smoking history, T stage, extracapsular lymph node extension, surgical margins or the human papillomavirus status. Overall, the presence of CTC was not predictive for OS or DFS. However, while in oropharyngeal carcinomas (OPC, n = 63), the detection of CTC was associated per trend with improved DFS [CTC+ versus CTC-(% of patients without evidence of disease at 2 years): 100% versus 79%; log rank: P = 0.059]; the reverse was observed for carcinomas from other sites (non-OPC, n = 81; CTC+ versus CTC-: 29% versus 75%; P = 0.001). In multivariate analysis, CTC remained an independent prognostic marker for DFS [hazard ratio (HR) 4.3, 95% confidence interval (CI) 1.7-10.9, P = 0.002] and OS (HR 2.7, 95% CI 1.2-6.3, P = 0.016) in non-OPC. Conclusions: Assessment of CTC in non-OPC should prove useful for identification of patients who benefit from treatment intensification. The basis for the good prognostic value of CTC in OPC has to be elucidated in future studies.