Aims: Fluorescence in situ hybridization (FISH) testing is the 'gold standard' method for Her-2 status assessment in breast cancer patients, yet is only employed in about 30% of tests carried out because of cost and labour considerations. We have previously described tissue microarray (TMA)-based testing to eliminate cost constraints, and now describe a rapid screening approach to reduce time spent testing.
Methods and results: We examined 88 cases of invasive breast cancer on TMAs comparing formal FISH scoring with a rapid screening technique. Each core was screened by two observers and results recorded as positive, equivocal or negative. Each approach was timed. Data were analysed by comparing the rapid screening results with formal counts. Using rapid screening, two-thirds of negative and half the positive cases could be eliminated with 100% accuracy. It took 2 min per observer per case to rapid screen six TMA cores at x100 magnification. The remaining cases required formal counting, which took no longer than with whole-section techniques.
Conclusion: Rapid screening of TMAs for routine Her-2 FISH testing is safe, economical and time efficient. The technique ensures that all patients receive 'gold standard' testing.