Eye-Tracking Experiments Underscore the Bias That Architecture Exerts on Nuclear Grading in Prostate Cancer
Dario Bombari, Braulio Mora, Stephan C Schaefer, Fred Mast, Hans-Anton Lehr. University of Bern, Bern, Switzerland; CHUV, Lausanne, Switzerland; Inselspital, Bern, Switzerland
Background: We recently described that nuclear grade assignment of prostate carcinomas is subject to a cognitive bias induced by the architectural organization of the tumor.
Design: Here, we asked whether this bias is mediated by the unconscious selection of nuclei that “match the expectation”. 20 pathologists were asked to grade nuclei in high power fields of prostate carcinomas on a computer screen, superimposed over a low power image of the tumor architecture. Unknown to the subjects, each carcinoma was shown twice, once before a background of a well-differentiated, tubule-rich carcinoma and once before the background of an undifferentiated, solid carcinoma. Eye tracking allowed to identify which nuclei the pathologists fixated on during the 8 second projection period.
Results: Nuclear grade assignment was significantly biased by the architectural differentiation of the tumors. “Gravitation” of nuclear grades towards the architectural grade depended on the magnitude of the architectural grade difference of the background images, but not on the experience of the pathologists. Most pathologists tended to fixate on bigger or darker nuclei when high power fields were projected before background images of undifferentiated, solid carcinomas and vice versa. However, the morphological differences of the thus selected nuclei accounted only for about 11% of the total bias induced by the tumor architecture.
Conclusions: We conclude that the selection of « matching nuclei » represents nothing but an unconscious effort to vindicate the bias induced by the architectural growth pattern.
Category: Quality Assurance
Monday, March 19, 2012 1:00 PM
Poster Session II # 268, Monday Afternoon