Challenging the concept of "risk of malignancy" in cytology.

Several standardized systems for nongynecological cytopathology have been published following the successful implementation of The Bethesda System for Reporting Cervical Cytology. Each of these systems comprises a set of reporting categories accompanied by a risk of malignancy. However, in most cases, these risk of malignancy estimates have not been based on high-quality evidence and often may not be consider proper "risks" (because they have been estimated based on cross-sectional studies). This commentary discusses the problems related to the data used to generate these risks. To make nongynecological cytopathology reporting more evidence-based, large-scale prospective cohort studies and randomized trials, in addition to high-quality systematic reviews and meta-analyses, should be performed.