NACT is known to induce a spectrum of histological changes in PDAC.7,8 Since the 1980s, several groups have proposed histopathological systems for the grading of response to chemo- and radiotherapy, aimed at developing a prognostic tool to guide postsurgical patient management.9–12 To date, these schemes have been based on the assessment of the amount of residual tumor, viability, tumor destruction, presence of mucin, and fibrosis. The gene discussed is MUC5AC; the disease is neoplasm.