Intraoperative scrape cytology: comparison with frozen sections, using receiver operating characteristic (ROC) curve

The diagnostic role of intraoperative cytology (IC) has been demonstrated by many comparative studies. These studies have used sensitivity and specificity as statistical tools, based on binary principles. Statistical methods based on binary principles appear to be inappropriate for comparing anatomic pathology studies which involve significant human judgment with a range of subjective nonbinary result patterns. In this study, we applied the receiver operating characteristic (ROC) curve, which is based on probabilistic principles for the comparison of diagnostic accuracy with IC and frozen sections (FS). Seven observers studied a variable number of IC alone, FS alone, and IC/FS together from a pool of 446 specimens. The results were analyzed by ROC curve, using the MEDCALC software program (MedCalc Software, Mariakerke, Belgium). The accuracy with IC alone and FS alone was comparable. IC alone was diagnostic for many lesions, offering the choice of not freezing the tissue, and thus avoiding the introduction of artifacts. This strongly favors the routine practice of preparing IC during intraoperative consultation.