Table 3. PD-L1 expression in tissue and peripheral blood of healthy controls and OSCC patients.

	n	mean ΔCT	SD	p-value	AUC	FC	COP	No. of cases	+	-	% pos. cases	p-value χ2 test
PD-L1_4 tissue	78			< 0.001	0.83	3.19	7.99	78	41	37		< 0.001
controls	35	8.82	1.11					35	6	29	17.1%
patients	43	7.15	1.59					43	35	8	81.4%
PD-L1_4 blood	75			0.165	nd	nd	nd	nd	nd	nd	nd	nd
controls	31	7.17	1.40
patients	44	6.90	1.24
PD-L1_2 tissue	74			< 0.001	0.76	3.18	10.37	74	40	34		< 0.001
controls	31	10.92	1.45					31	8	23	25.8%
patients	43	9.25	1.94					43	32	11	74.4%
PD-L1_2 blood	75			0.287	nd	nd	nd	nd	nd	nd	nd	nd
controls	31	7.10	1.33
patients	44	6.92	1.21

Comparison of PD-L1 mRNA expression between OSCC patients (group patients) and healthy volunteers (group controls). Expression of PD-L1 splicing variants 1 and 4 (PD-L1_4) and splicing variants 1 and 2 (PD-L1_2) in tissue (OSCC tumor tissue vs. healthy oral mucosa of volunteers) and peripheral blood was analyzed. The mean ΔCT value (mean), standard deviation (SD) and the p-value provided by the Mann-Whitney U test are shown. Higher ΔCT values indicate lower PD-L1 mRNA expression. Regarding PD-L1 expression in tissue, area under the curve (AUC), fold-change FC and cut-off point (COP) values are given. Based on their ΔCT value related to the COP, the cases were determined as positive (malignant) and negative (healthy). The percentage of positive tested cases (% pos. cases) in the controls and patients group is presented. A Statistical analysis was carried out by the Chi-square test (χ² test). Fold-change (FC) of PD-L1 mRNA expression was determined by the ΔΔCT method comparing the average ΔCT values of the two groups. nd: not determined.