Tissue microarrays: emerging standard for biomarker validation.

With the widespread use of DNA microarrays, hundreds of biomarkers are in need of validation in cohorts of well-annotated clinical samples. Tissue microarrays are emerging as the tool par excellence to rapidly perform DNA, RNA, and especially protein expression analyses on large numbers of clinical samples. Although still somewhat limited by the subjectivity of scoring methods and tissue sample representativeness, TMAs represent an increasingly validated means of understanding the clinical impact of diagnostic-related, prognostic-related, and therapy-related markers. Automated methods are being developed for TMA analysis and cell microarrays and frozen tissue TMAs have been better optimized. More and more biomarker studies are availing themselves of the high-throughput nature of TMAs, recognizing that they are becoming indispensable for rapid translation of laboratory data to the clinic.