Pre-treatment circulating tumour cells (CTC) numbers correlate with treatment response in patients with head and neck cancer, Queensland researchers have shown.

A Griffith University study compromised 135 adult patients with locoregionally advanced SCCs of the head and neck mucosa. Patients were mostly those with p16 positive oropharyngeal cancer (OPC) and other head and neck cancers of the oral cavity cancer, p16 negative OPC, hypopharynx cancer, larynx cancer and cancer with unknown primary site.

Salivary gland, thyroid and nasopharynx cancer and patients with metastatic cutaneous malignancies were excluded from the study.

All HNC patients were treatment-naïve at the time of baseline blood collection. Patient treatment responses were determined by analysing the clinical reports of FDG-PET-CT imaging and MDT consensus at 13 weeks post-treatment.

CTCs were successfully isolated and enriched using a novel spiral microfluidic device and identified using immunofluorescence staining.

The study, published in Cellular Oncology, found that the absence of CTCs at diagnosis was positively correlated with treatment outcomes in HNC patients.

In patients with no CTCs at baseline, 98.3% achieved a complete response at 13 weeks, and only 1.7% had an incomplete response.

“At least 1 baseline CTC was detected in 50.04% of HNC patients and in 90.9% (10/11) of HNC patients with an incomplete response based on 13th week PET-CT scan results and MDT decision making.”

“Furthermore, the mean baseline CTC count was found to be significantly higher in HNC patients with an incomplete response compared to that in patients with a complete response (2.33 vs. 1.58).”

The study also found the expression level of cell-surface vimentin (CSV) on CTCs was significantly higher in patients with persistent or progressive disease, thus providing additional prognostic information for stratifying the risk at diagnosis in HNC patients.

“The ability to detect CTCs at diagnosis allows more accurate risk stratification, which in the future may be translated into better patient selection for treatment intensification and/or de-intensification strategies.”

Professor Chamindie Punyadeera, from the Saliva and Liquid Biopsy Translational Laboratory at the Griffith Institute for Drug Discovery, told the limbic that risk stratification at baseline would provide an opportunity to step up or down the intensity of treatment.

“We have 11 patients who have incomplete response, and 10 of them have CTC at the point when they were diagnosed with cancer. So it’s like 80-90% sensitive. So what we’re trying to say here is that we can at least stratify or predict outcome using CTC numbers.”

She said CTC platforms were FDA-approved for prostate, colorectal and breast cancer but not yet for head and neck cancer which was an area of unmet clinical need.

The current study will continue to follow patients at 6, 12 and 24 months, providing the scientific evidence ahead of a clinical trial.

The study was funded by Cancer Australia.