Potential role of tissue microarrays for the study of biomarker expression in benign breast disease and normal breast tissue.

BACKGROUND: Tissue microarrays (TMAs) are commonly used to study biomarker expression in invasive breast cancers. Whether or not TMAs may also be a potentially useful platform for assessing biomarkers in benign proliferative breast lesions (BPBL) and normal breast tissue has not been previously studied in detail.
METHODS: We evaluated the success of capturing the targeted areas in TMAs constructed from benign breast biopsy blocks of 368 Nurses' Health Study and Nurses' Health Study II participants. Areas targeted included 214 BPBL and 361 normal terminal duct lobular units (TDLUs). At least three 0.6 mm cores were obtained from the areas of interest from each donor paraffin block and arrayed into a recipient block. Sections cut from TMA blocks were stained with hematoxylin and eosin. Each TMA slide was examined to determine the number of cores per case in which the targeted area was represented.
RESULTS: Overall, the targeted area was present in 776 of 1800 TMA cores (43%). At least 1 of the cores contained the area of interest for 401 of the 575 targeted foci (70%), including 76%, 66%, 60%, and 40% of cases in which the targeted areas were normal TDLUs, usual ductal hyperplasia, atypical lobular hyperplasia, and atypical ductal hyperplasia, respectively.
CONCLUSIONS: In TMAs constructed from BPBL and normal TDLUs, the targeted area was present on at least 1 core in 70% of cases. Our findings indicate that it is feasible to construct TMAs from donor tissue blocks consisting of BPBLs and normal breast tissue with a relatively high rate of capture of the targeted area.