Associations of Tumor PD-1 Ligands, Immunohistochemical Studies, and Textural Features in 18F-FDG PET in Squamous Cell Carcinoma of the Head and Neck

Abstract

To know tumor PD-L1 expression through IHC or the FDG-PET related radiomics, we investigated the association between programmed cell death protein 1 ligand (PD-L1) expression and immunohistochemical (IHC) biomarkers or textural features of 18F-fluoro-2-deoxdeoxyglucose positron emission tomography (¹⁸F-FDG PET) in 53 oropharyngeal or hypopharyngeal cancer patients who were ready to undergo radiotherapy-based treatment. Differences in textural features or biomarkers between tumors with and without PD-L1 expression were tested using a Mann-Whitney U test. The predicted values for PD-L1 expression were examined using logistic regression analysis. The mean percentages of tumor PD-L1 expression were 6.2 ± 13.5. Eighteen tumors had PD-L1 expression ≥5%, whereas 30 tumors ≥1%. Using a 5% cutoff, the p16 staining percentage and the textural index of correlation were two factors associated with PD-L1 expression. The odds ratios (ORs) were 17.00 (p = 0.028) and 0.009 (p = 0.015), respectively. When dichotomizing PD-L1 at 1%, the p16 and Ki-67 staining percentages were two predictors for PD-L1 expression with ORs of 11.41 (p = 0.035) and 757.77 (p = 0.045). p16 and Ki-67 staining percentages and several PET/CT-derived textural features can provide supplemental information to determine tumor PD-L1 expression in HNCs.

Figure 1

PD-L1 expression of ≥5% associated with quantitative values of the IHC intensity of p16 (1 A), textural index of correlation (IB), and their ROC curves (1 C). The AUCs for p16 and the textural index of correlation were 0.72 ± 0.07 (p = 0.011) and 0.24 ± 0.07 (p = 0.002), respectively.

Figure 2

PD-L1 expression of ≥1% associated with the quantitative values of the IHC intensity of p16 (1 A), Ki-67 (IB), and their ROC curves (1 C). The AUCs for p16 and the textural index of correlation were 0.75 ± 0.06 (p = 0.002) and 0.72 ± 0.07 (p = 0.006), respectively.