Abstract B30: Clinical correlation of circulating tumor cells as a blood marker in Indian head and neck cancer patients
Authors: Khandare Jayant , Qayyumi Burhanuddin Nuruddin , Bharde Atul , Aland Gourishankar , Sagare Ajit , Tripathi Swati , Singh Nitin , Jayant Sreeja , Muglikar Ashish , Badave Reecha , Vasudevan Aravindan , Prabhash Kumar , Chaturvedi Pankaj 
Published: June 2020

Objectives: To establish a rapid, highly specific, efficient, sensitive, and affordable CTC enumeration liquid biopsy technology and to validate its efficacy to isolate CTC disseminating from epithelial tumors of HNC subpopulation in India. Furthermore, to study the correlation of CTC distribution from peripheral blood with respect to various clinicopathologic factors in these patients.

Materials and Methods: A cross-sectional study was conducted using peripheral blood from enrolled 350 HNC patients. CTC were isolated using DCGI, India-approved technology, that exploits EpCAM-based immunomagnetic separation. EpCAM+ tumor cells were isolated from only 1.5 mL blood and critically assayed for cytokeratin 18 (CK18) expression and quantified using fluorescence imaging of CTCs so as to obtain a threshold to further minimize nonspecific and false-positive enumeration. CTC enumeration was subsequently subjected to statistical correlation with various clinical and pathologic parameters.

Results: We detected CTCs from all HNC patients across its various subsites, and there was a minimum threshold of at least 12 CTC in early oral cancer patients according to their clinicopathologic signatures. Compared to early oral cancer patients, advanced nodal patients showed 40% escalation in CTC count, while up to 80% increase in CTC count was observed when associated with aggressive features such as lymphovascular emboli (LVE) and with extranodal extensions. Of note, laryngopharyngeal primary had the highest mean CTC count of 33 in 1.5mL blood. Conversely, patients with advanced disease had higher CTC count and this was staggered in comparison with nearly but not all of the clinical features. Remarkably, higher clinical N (nodal) stage statistically correlated with increased CTC count and a marked increase in CTC was seen in tumors that showed lymphovascular emboli on histopathology and extranodal extension. The CTC counts were independent of parameters such as the age, sex, T stage, perineural invasion, bone involvement, or skin involvement. There was a notable trend towards reduced CTC count after chemotherapy; however, it was not statistically significant.

Conclusion: Our rapid and efficient CTC platform has demonstrated and clinically validated its use in Indian HNC phenotypes. This is the first comprehensive study to show a staggering positive correlation of CTC with various clinicopathologic factors. It comprised the largest number of oral cancer patients throughout the entire spectrum of HNSCC, the most common cancer in India. High CTC counts among HNC patients could possibly be one of the reasons for their dismal outcomes, and further studies with a correlation of CTC with patient survival in HNC are warranted. However, this study strongly implicates a perspective utility of CTC as a tumor marker in establishing the clinical staging in HNC patients.

Citation Format: Jayant Khandare, Burhanuddin Nuruddin Qayyumi, Atul Bharde, Gourishankar Aland, Ajit Sagare, Swati Tripathi, Nitin Singh, Sreeja Jayant, Ashish Muglikar, Reecha Badave, Aravindan Vasudevan, Kumar Prabhash, Pankaj Chaturvedi. Clinical correlation of circulating tumor cells as a blood marker in Indian head and neck cancer patients [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B30.