Validation of Tissue Microarray for Immunohistochemical Analysis of Oral Squamous Cell Carcinoma by Using Virtual Cores

Background: There is significant amount of research done on Oral Squamous cell carcinoma (OSCC). One research technique is immunohistochemical (IHC) analysis using whole sections. With little availability of OSCC tissues high throughput analysis such as Tissue Microarray (TMA) are capable of efficient analysis of small samples. However, the results become questionable if the tumor exhibits high degree of heterogeneity as TMA cores might not accurately represent the whole section. Aim: The aim of this study is to determine the optimal number of TMA cores required to provide an accurate representation of the whole section with IHC analysis in OSCC. Materials and Methods: Twenty tissue samples stained with anti-p53 antibody were scanned at 40x magnification. Three to six virtual cores of size 0.6 mm, 1.0 mm and 1.5 mm were drawn on the scanned slides. H-scores were obtained for both whole sections and cores using NuclearQuant (3DHistech, Budapest, Hungary) software after eliminating non-tumour cells and artifacts manually. The correspondence between the cores and whole sections were calculated using intra-class correlation and one sample t-test. Results: Good correlation was obtained with just a single core of 0.6mm (0.826). Subsequent increase in core number and size resulted in improved correlation coefficient and smaller confidence interval. Conclusion: Three TMA cores of 0.6 mm would be the most optimal, as not only was there very strong correlation with the whole tissue section, the extra core will also be able to act as confirmation if the results of the first 2 cores are in doubt.