Discordant Immune Marker Expression Between Preoperatively Biopsied and Matched Surgically Resected Specimens in Patients With Oral Squamous Cell Carcinoma

Programmed cell death ligand 1 (PD-L1) expression and tumor-associated immune cell (TAIC) density can be the biomarkers of survival outcome and for predicting the efficacy of immune checkpoint inhibitors in oral squamous cell carcinoma (OSCC), but whether single biopsy accurately reflects the values of these parameters in resected specimens is unclear. To clarify this, we evaluated the concordance of immune marker expression (PD-L1, PD-1, CD3, CD4, CD8, and CD68) between 39 paired biopsied and surgically resected specimens obtained from patients with OSCC at Kobe City Medical Center General Hospital between July 2011 and January 2016. Immune marker expression was assessed using immunohistochemistry. PD-L1 expression was consistent between the biopsied and surgically resected specimens in only 76.9% of cases. TAIC density was significantly lower in biopsied than in surgically resected specimens. There was considerable discordance in immune marker expression between biopsied and surgically resected specimens. We should take into consideration that PD-L1 positivity and TAIC density would be underestimated by single small biopsies compared to the estimations by surgically resected specimens.