Tsai S, George B, Wittmann D, et al. - Given carbohydrate antigen 19-9 (CA19-9) is an established prognostic marker in pancreatic cancer (PC), researchers tried to clarify how CA19-9 monitoring should be employed to guide multimodality treatment. They also investigated what level of alteration in CA19-9 constitutes a meaningful treatment response. The participants were patients with localized PC who exhibited a high CA19-9 (≥ 35 U/dL) at diagnosis. Among participants, CA19-9 measurements were evaluated at diagnosis (pretx), following completion of all planned neoadjuvant therapy (preop), and following surgery (postop). Experts categorized patients by: quartiles of pretx CA19-9 (Q1-4); proportional alterations in CA19-9 (ΔCA19-9) following the completion of neoadjuvant therapy; normalization (CA19-9 < 35 U/dL) of preop CA19-9; and normalization of postop CA19-9. According to the findings, after neoadjuvant therapy, the strongest prognostic marker for long-term survival was normalization of CA19-9, rather than the magnitude of change.