Multiparameter analysis of DNA content and cytokeratin expression in breast carcinoma by laser scanning cytometry.

OBJECTIVE The objective of this study was to test a new laboratory technology, laser scanning cytometry, for the purpose of performing multiparameter DNA content analysis of breast carcinomas. DESIGN We developed a simplified method of multiparameter DNA content analysis using cytokeratin expression to positively gate epithelial cells. Over 300 consecutive cases of breast carcinoma were analyzed by multiparameter laser scanning cytometry. The first 73 cases were analyzed in parallel by single parameter flow cytometry. SETTING The Department of Pathology, Christ Hospital and Medical Center, Oak Lawn, Ill. SPECIMENS Three hundred eighteen consecutive cases of breast carcinoma presenting between March 1994 and December 1995. MAIN OUTCOME MEASURES Outcome measures included the percentage of cases for which DNA content analysis could be successfully performed given the limitations of specimen size. Additionally, for the first 73 cases, laser scanning cytometry results were compared with flow cytometry results. RESULTS All of the first 73 cases were successfully analyzed by laser scanning cytometry, but for 8 cases (11%) there was insufficient material for flow cytometry. Correlation of DNA content for the remaining 65 cases analyzed in parallel by the two methods was nearly perfect (p = .994). Five seemingly discrepant cases highlighted the importance of cytokeratin gating of epithelial cells by any technique, as well as other advantages specific to laser scanning cytometry, such as the ability to examine individual cells microscopically and correlate cytologic morphology with DNA content results. CONCLUSIONS Laser scanning cytometry is a promising new technology for DNA content analysis of solid tissue tumors. Further work needs to be performed to validate the prognostic potential of the laser scanning cytometric assay results and to generate methodologies aimed at providing highly objective determinations of tumor cell S-phase fraction.