Tissue microarrays have rapidly become a vital tool in the analysis of protein biomarkers on large patient cohorts. Composed of hundreds of miniature histologic tissue cores taken from patient tumors and arrayed in a grid pattern, tissue microarrays have great potential for automation. However, unlike DNA/RNA expression arrays, they contain spatial information, such that successful automation requires both the ability to quantitate and localize biomarkers within the tissue. This review traces tissue microarray analysis from the simplest of systems (visual inspection) to dedicated, automated quantitative analyzers capable of localizing biomarkers to sub-cellular compartments. It focuses on the importance of automating the process of tissue microarray analysis, while commenting on the inherent problems associated with both manual and automated analysis. Finally, it discusses the future of automated tissue microarray analysis, emphasizing the many areas of development and potential improvement.

Although much has been written about overdiagnosis in mammographical screening, analytical estimates of the extent of overdiagnosis are rare in the literature. Estimates specific to ductal carcinoma in situ (DCIS) and the implications for future invasive disease are even more difficult to find. In this paper, we review studies of incidence of DCIS within breast screening programmes and its association with subsequent incidence of invasive breast cancer. Although sparse, published results suggest that the majority of DCIS cases have the propensity to progress to invasive disease.