Utilization of Cell-Transfer Technique for Molecular Testing on H&E-stained Sections- A Viable Option for Small Biopsies that Lack Tumor Tissues in Paraffin Block

Abstract

Context.— In some instances the standard method of doing molecular testing from formalin-fixed, paraffin-embedded block is not possible because of limited tissue. Tumor cell–enriched cell-transfer technique has been proven useful for performing immunocytochemistry and molecular testing on cytologic smears. Objective.— To establish the cell-transfer technique as a viable option for isolating tumor cells from hematoxylin-eosin (H&E)–stained slides. Design.— Molecular testing was performed by using the cell-transfer technique on 97 archived H&E-stained slides from a variety of different tumors. Results were compared to the conventional method of molecular testing. Results.— Polymerase chain reaction–based molecular testing via the cell-transfer technique was successfully performed on 82 of 97 samples (85%). This included 39 of 47 cases for EGFR, 10 of 11 cases for BRAF, and 33 of 39 cases for KRAS mutations. Eighty-one of 82 cell-transfer technique samples (99%) showed agreement with previous standard method results, including 4 mutations and 35 wild-type alleles for EGFR, 4 mutations and 6 wild-type alleles for BRAF, and 11 mutations and 21 wild-type alleles for KRAS. There was only 1 discrepancy: a cell-transfer technique with a false-negative >KRAS result (wild type versus G12C). Conclusions.— Molecular testing performed on H&E-stained sections via cell-transfer technique is useful when tissue from cell blocks and small surgical biopsy samples is exhausted and the only available material for testing is on H&E-stained slides.