Table 2.

Summary of Proposed Recommendations

Recommendations
Collection of the blocks to form the cohort
Write a protocol for the proposed study, including prospective design of the collection methods, anticipated studies to be performed, and statistical analyses to be completed, if known at the time of array construction.
Determine whether tissue subset available for TMA is consistent with total cohort with respect to relative risk of effect of primary end point of study. If representative and powered, then proceed to block review. If not representative, consider conversion to case-control series or selected cases series, or consider repeating efforts to obtain more blocks.
HE-stained slides from each block must be reviewed by a qualified reviewer (usually a pathologist) to define the region of interest for coring. Establish the cohort of patients who have acceptable amounts of target tissue for the specified TMA design.
Array construction issues
For large cohorts, use the 0.6-mm core size unless tissue type or TMA need justifies larger core.
To prevent map orientation confusion, use asymmetric array construction.
Use at least two-fold nonadjacent redundancy.
Include appropriate controls on every TMA master block.
If greater than one core from each patient is to be used in a single master block, we recommend nonadjacent placement of the cores.
Postconstruction array validation
Slides should be stained as soon as feasible after cutting (within 5 days) of the blocks or appropriately preserved. To minimize loss, TMA master blocks should be cut in batches of at least 10 slides to minimize loss related to facing the block.
Quality control should include HE staining and pathologist review of at least every 20th cut.
Statistical review of the final cohort from whom biomarker data were obtained should include assessment of the subset of the cohort missing from the TMA to be sure missing patients as a result of technical issues do not introduce bias into the cohort analysis, and comparison of row means and column means on each TMA section and between TMA blocks stained for the same biomarker to identify any systemic bias in data collection.

Abbreviations: TMA, tissue microarray; HE, hematoxylin and eosin.