Prognostic Utility Of Circulating Tumor Cells/Cell Clusters In Head And Neck Cancers.

Abstract Background: Metastases remains the major cause of death in head and neck cancer (HNC) patients. Circulating tumour cells (CTCs) that are shed from primary and metastatic sites and circulate in patients' peripheral blood, represent an important window into disease status. Minimally invasive techniques are required to identify at time of diagnosis, which patients will have worse prognosis due to distant relapse. Method: We collected bloods from treatment naïve, locoregionally advanced HNC patients (n=72) at the time of diagnosis, and CTCs were isolated using a spiral microfluidic device. CTCs were then immobilised onto glass slides and identified by using immunofluorescence staining (Cytokeratin/CD45/DAPI). We then correlated the CTC numbers of each patient to their clinical outcome based on either PET/CT scan and/or clinical assessment after definitive treatment. Results: CTCs were detected in 39/72 (54%) of patients (ranging from 1-18 CTCs/10 mL blood) at diagnosis. CTC numbers were correlated to TNM staging (p<0.01), especially the Node staging (p<0.01). Patients with ≥2 CTCs at baseline showed significantly worse prognosis than those with no CTCs detected (P<0.001). We also found that baseline CTCs is an independent predictor of the adverse clinical outcome (residual disease, recurrence, and equivocal clinical presentation) even after adjusting to other prognostic factors (hazard ratio=4.613, p<0.05). Patients with CTC cluster had poor prognosis compared to patients with single CTCs. Conclusion: We were able to predict disease progression based on CTC numbers, thus providing potential additional prognostic information for locally advanced HNC patients. The ability to detect CTCs at diagnosis allows us to stratify the risk in patients as well as to understand the fundamental mechanisms by which CTCs spread. The clinical benefit of establishing the use of CTCs in HNC is likely to translate into better patient selection for treatment intensification and/or de-intensification strategies. Citation Format: Xi Zhang, Kai Tang, Brett Hughes, Sarj Vasani, Zhen Liu, Majid Warkiani, Gunter Hartel, Rahul Ladwa, Liz Kenny, Chamindie Punyadeera. Prognostic utility of circulating tumor cells/cell clusters in head and neck cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 602.