Relationships between ADC histogram analysis parameters and PD-L 1-expression in head and neck squamous cell carcinomas. A preliminary study.

Correlations between ADC and PD-L 1 in HNSCC

Abstract

Background. Programmed death 1 ligand (PD-L 1) treatment has become a cornerstone of the novel anticancer immunotherapy. It might be crucial to predict its expression non-invasively by imaging. The present study used Diffusion-weighted imaging quantified by whole lesion apparent diffusion coefficient (ADC) values to elucidate possible associations with PD-L 1 expression in head and neck squamous cell cancer (HNSCC).

Patients and methods. Overall, 29 patients with primary HNSCC of different localizations were involved in the study. DWI was obtained by using a sequence with b-values of 0 and 800 s/mm² on a 3 T MRI. ADC values were evaluated with a whole lesion measurement and a histogram approach. PD-L 1 expression was estimated on bioptic samples before any form of treatment using 3 scores (Tumor positive score, Immune cell score, ICS and Combined positive score).

Results. An inverse correlation between skewness and ICS was identified (r=-0.38, p=0.04). There was a trend for ADCmax to correlate with ICS (r=-0.35, p=0.06) but did not reach statistical significance). The other parameters did not show any association with the calculated scores.

Conclusions. There is a weak association between skewness derived from ADC values and PD-L 1 expression in HNSCC, which might not be strong enough to predict PD-L 1 expression in clinical routine. Presumably, ADC values are more influenced by the whole amount of tumor cells than only of a single subset of tumor associated cells.