Background

Head and neck squamous cell carcinoma is the leading cancer in India, with oral squamous cell carcinoma (OSCC) as the most frequent subtype. OSCC is classified as a locoregional disease, and its increased frequency is attributed to a lack of effective biomarkers compared to other epithelial cancers. At the time of diagnosis, above 50% of cases present with advanced-stage disease and are predisposed to treatment failure despite appropriate intervention. Thus, early diagnosis of OSCC can significantly reduce the disease burden. Here, we describe a regulatory-approved method to establish the presence of circulating tumor cells (CTCs) in Indian OSCC patients and its positive correlation with various clinicopathological parameters, suggesting the potential use of CTCs as a significant parameter to stratify oral cancer with respect to disease advancement.

Methods

In a cross-sectional observational study, 230 OSCC patients at different pathological stages of the disease and treatment modes were enrolled. CTCs were isolated using the approved OncoDiscover liquid biopsy technology (approved by the Drug Controller General of India), a platform based on immunomagnetic CTC enumeration. CTCs were detected for CK18 presence and well-defined, DAPI-stained nuclei. Enumerated CTCs were subsequently analyzed for various clinicopathological parameters such as pathological stage (pStage), extra-capsular spread (ECS), lymphovascular emboli (LVE), perineural invasion (PNI), and depth of invasion (DOI). CTC cut-off values were obtained to differentiate early vs. advanced stages with respect to different clinical stages and parameters.

Results

CTCs of OSCC patients correlated positively with cancer stages (clinical as well as pathological) as well as aggressive pathological features. In the presence of aggressive pathological features that often suggest a poor disease outcome, we observed a 25–50% increase in CTC numbers. Early-stage, treatment-naive patients had a lower number of CTCs. The mean CTC number in advanced-stage patients was 50% higher than in early-stage OSCC patients.

Conclusions

Considering the positive correlation of CTC numbers with various pathophysiological features, CTCs can be contemplated as a reliable parameter to predict disease outcome in oral cancer. The consistent presence of CTCs across all disease stages also suggests the probable nature of OSCC as a biological systemic disease.

Clinical Trial Information

CTRI/2018/03/012905.