PD-L1 Expression and Ultrasound Characteristics in Papillary Thyroid Carcinoma and Its Effect on Recurrence.

Abstract

Programmed death-ligand 1 (PD-L1) is a component of the tumor microenvironment, which is closely involved in the occurrence and development of tumors. We investigated the correlation between the expression of PD-L1 and ultrasound characteristics in papillary thyroid carcinoma (PTC) and its effect on recurrence. Fifty-two patients at the Department of General Surgery of Qingdao Municipal Hospital underwent thyroid ultrasonic examination before surgery and their clinicopathological variables were collected. Then, immunohistochemistry staining was conducted to evaluate the PD-L1 expression in tumors and adjacent normal tissues. The correlations of PD-L1 expression with clinicopathological and ultrasound characteristics were analyzed. The expression of PD-L1 was positive in 59.7% (40/67) of PTC tumor tissues. In clinicopathological analyses, PD-L1 positivity was related to multifocality of tumors (p=0.031). In analyses of ultrasound characteristics, the expression of PD-L1 was positively correlated with halo sign (p=0.035), capsular invasion (p=0.003), microcalcification (p=0.02), and recurrence (p=0.009). In multivariate logistic analysis of ultrasonic characteristics and recurrence of thyroid carcinoma, microcalcification [odds ratio=13.349, 95% confidence interval (CI)=2.052-86.832, p=0.007] and the halo sign (odds ratio=15.273, 95% CI=1.451-160.747, p=0.023) were factors associated with recurrence of PTC. In the multivariate Cox regression analysis, positive PD-L1 staining [hazard ratio (HR)=5.031, 95% CI=1.092-23.172, p=0.038] and a halo sign (HR=4.998, 95% CI=1.084-23.051, p=0.039) were independent predictors for poorer recurrence-free survival. Positive expression of PD-L1 predicted worse recurrence-free survival in the subgroup of patients with a halo sign (HR=6.537, 95% CI=1.863-22.94, p=0.037). Positive expression of PD-L1 in PTC affects the clinical and ultrasonic characteristics of the tumor and may negatively affect the prognosis of patients with PTC.