Abstract
This editorial comments on Yang et al's article that reported a correlation between dynamic contrast-enhanced ultrasound (CEUS) quantitative parameters and Ki67/tumor differentiation. The validation of CEUS as a diagnostic modality in this study deserves merit. However, it raises interesting points of discussion: (1) Since pancreatic cancer is an overarching term that includes conventional pancreatic ductal adenocarcinoma (PDAC), other subtypes, and neuroendocrine neoplasms (NENs), the inclusion/exclusion criteria require better clarification; (2) Most PDACs are grade 1-2 which contrasts with Yang et al's study where 46% were grade 3; (3) Ki67 is officially recognized for grading NENs, but not for PDAC; (4) Hotspots are selected for the Ki67 grading of NENs. However, for other tumors (e.g., breast carcinoma), the average count or hotspots are used; (5) There is no agreement for defining high-grade Ki67 cut-off for non-NENs; reports range from 10% to 50%; and (6) Ki67 reflects cellular proliferation but is not always the most important indicator for biologic aggressiveness. That notwithstanding, since the ratification of Ki67 for prognosis in NENs was based on survival outcomes, the real gold standard should be survival, instead of using Ki67 as a surrogate gold standard. In conclusion, the validation of CEUS parameters for PDAC is a work in progress. CEUS is valuable in assessing PDAC but should be viewed as augmenting other modalities such as computed tomography, magnetic resonance imaging, positron emission tomography and endoscopic ultrasound.