Evaluation of a new slide-based laser scanning cytometer for DNA analysis of tumors: Comparison with flow cytometry and image analysis

DNA measurements generated by a new automated slide-based cytometer, the laser scanning cytometer (LSC), were compared with those produced by commercial flow cytometry (FCM) and image analysis (IA) devices. Laser scanning-cytometric analysis was performed by scanning alcohol-fixed, propidium iodide-stained tumor imprints with a 5-μm spot laser beam. Fifty- three malignant tumors (51 breast carcinomas and 2 lung carcinomas) were studied. Ploidy concordance rates for FCM versus LSC, IA versus LSC, and FCM versus IA were 96%, 91%, and 91%, respectively. Statistically significant agreement between methods was determined by linear regression analysis of DNA indices. Synthesis-phase fractions generated by FCM and LSC also were comparable, as demonstrated by linear regression (r = .83). Mean coefficients of variation for the LSC compared favorably with those for FCM and IA. The few discrepancies in ploidy status between methods could be explained by sampling error, the presence of possible near-diploid aneuploid populations that could not be effectively resolved by one or another modality, and the visual selection bias with IA when small aneuploid cell populations were present. The LSC shares many useful features with FCM, including automation, accuracy of quantitation, rapidity, and generation of reliable information regarding cell proliferation (synthesis-phase fraction). In addition, it has some of the advantages of IA, such as minimal tissue requirement, no need for special preparation, and the potential for visual selection of the cells measured. The LSC holds great promise for use in the clinical laboratory because of these combined characteristics.