Anaplastic Thyroid Carcinoma Exhibits Intratumoral Molecular Homogeneity for a Therapeutic Target Panel

Background: The objective of this work was to determine if molecular heterogeneity exists between different intratumoral histological subtype foci of anaplastic thyroid carcinoma (ATC). Materials and Methods: A tissue microarray composed of 12 ATC specimens from 6 patients (two discrete histological subtype foci from each tumor) were evaluated for expression of 51 different molecular markers. Significant associations between marker staining and tumor focus (primary versus secondary) or subtype (epithelioid, giant cell, or spindled) were determined using contingency table statistics and samples and markers were clustered using a hierarchical clustering algorithm. Correlation between marker staining for the two tumor foci was also evaluated for each patient using a Spearman correlation. Results: Significant correlations and clustering were observed for the overall staining patterns for paired anaplastic foci from the same patient. This suggests that the different intratumoral foci showed consistent or homogeneous staining. Conclusion: These results suggest that observed ATC phenotypic heterogeneity does not necessarily reflect heterogeneity for therapeutic target expression.