INTRODUCTION

High incidence rates of cervical cancer (CC) are reported in Sub-Saharan Africa (SSA). The vast majority of CCs are associated with persistent high-risk human papilloma virus (hrHPV) infection. p16 is overexpressed in HPV infected cells thus it is used as a surrogate marker for HPV. In SSA a high incidence of CC is occurring in an HIV pandemic milieu. Thus, a recent therapeutical biomarker as PDL-1 expression could also be of interest to study in an SSA setting. Biomarkers studies using whole slide (WS) preparations yields a high cost per case, thus cost-effective methods as tissue microarray (TMA) are of importance to facilitate SSA based clinical research.

OBJECTIVE: To evaluate the effectiveness of TMA in p16 and PDL-1 expression in CC compared to WS.

METHODS: We selected and anonymized 20 cases of CC diagnosed at Orebro university hospital. p16 and PDL1 expression was immunohistochemically investigated.  All WS were scanned, ten representative virtual TMA cores per sample were selected with 0.6 mm in diameter and scored. 10 random combinations of 3 cylinders per case were assessed for each marker. Each cylinder and WS was considered was considered negative or positive for p16 and PDL1. Agreement of scoring between TMA samples and whole sections were evaluated by kappa statistics.

RESULTS: p16 WS was considered as positive in 19 cases with a kappa value of 1.00 (1.00-1.00, 95% confidence interval) concerning TMA evaluation.  PDL-1 was scored as negative in 15 cases and positive in 5 on WS, with a TMA concordance with k=0.66 (0.54-0.79). Thus, TMA agreement was excellently and substantial for the evaluated biomarkers.

CONCLUSIONS: TMA is a valuable method in the research setting and is a cost-effective tool for cancer research especially in the SSA setting. However, each biomarker needs to be assessed concerning TMA and WS concordance.