Carbohydrate antigen (CA) 19–9 levels after resection are considered to predict prognosis; however, the significance of decreased CA19–9 levels after neoadjuvant therapy has not been clarified. This study aimed to define the prognostic significance of decreased CA19–9 levels after neoadjuvant therapy in patients with pancreatic adenocarcinoma. Between 2001 and 2012, 240 consecutive patients received neoadjuvant therapy and subsequent resection at seven high-volume institutions in Japan. These patients were divided into three groups: Normal group (no elevation [≤37 U/ml] before and after neoadjuvant therapy), Responder group (elevated levels [> 37 U/ml] before neoadjuvant therapy but decreased levels [≤37 U/ml] afterwards), and Non-responder group (elevated levels [> 37 U/ml] after neoadjuvant therapy). Analyses of overall survival and recurrence patterns were performed. Uni- and multivariate analyses were performed to clarify the clinicopathological factors influencing overall survival. The initial metastasis sites were also evaluated in these groups. The Responder group received a better prognosis than the Non-responder group (3-year overall survival: 50.6 and 41.6%, respectively, P = 0.026), but the prognosis was comparable to the Normal group (3-year overall survival: 54.2%, P = 0.934). According to the analysis of the receiver operating characteristic curve, the CA19–9 cut-off level defined as no elevation after neoadjuvant therapy was ≤103 U/ml. The multivariate analysis revealed that a CA19–9 level ≤ 103 U/ml, (P = 0.010, hazard ratio: 1.711; 95% confidence interval: 1.133–2.639), tumor size ≤27 mm (P = 0.040, 1.517; (1.018–2.278)), a lack of lymph node metastasis (P = 0.002, 1.905; (1.276–2.875)), and R0 status (P = 0.045, 1.659; 1.012–2.627) were significant predictors of overall survival. Moreover, the Responder group showed a lower risk of hepatic recurrence (18%) compared to the Non-responder group (31%), though no significant difference in loco-regional, peritoneal or other distant recurrence were observed between groups (P = 0.058, P = 0.700 and P = 0.350, respectively). Decreased CA19–9 levels after neoadjuvant therapy predicts a better prognosis, with low incidence of hepatic recurrence after surgery.

Cholangiocarcinoma is an aggressive malignant tumor originating from intrahepatic or extrahepatic bile ducts. Its malignant phenotypes may be assumed by cancer stem cells (CSC). Here, we demonstrate that CD274 (PD‐L1), known as an immunomodulatory ligand, has suppressive effects on CSC‐related phenotypes of cholangiocarcinoma. Using two human cholangiocarcinoma cell lines, RBE and HuCCT1, we attempted to isolate the CD274^low and CD274^high cells from each cell line, and xenografted them into immunodeficient NOD⁄scid⁄γcnull (NOG) mice. We found that the CD274^low cells isolated from both RBE and HuCCT1 are highly tumorigenic in NOG mice compared with CD274^high cells. Furthermore, the CD274^low cells possess several CSC‐related characteristics, such as high aldehyde dehydrogenase (ALDH) activity, reduced reactive oxygen species production and a dormant state in the cell cycle. Furthermore, depletion of CD274 expression by shRNA in RBE cells enhances their tumorigenicity and increases ALDH activity. These findings are compatible with our observation that clinical cholangiocarcinoma specimens are classified into low and high groups for CD274 expression, and the CD274 low group shows poorer prognosis when compared with the CD274 high group. These results strongly suggest that CD274 has a novel function in the negative regulation of CSC‐related phenotypes in human cholangiocarcinoma, which is distinct from its immunomodulatory actions.

Aim: This study aimed to clarify the usefulness of tumor markers from peritoneal lavage in selecting patients with a high risk of recurrence and predicting site‐specific recurrence in patients with pancreatic cancer.Methods: The levels of serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19–9 (sCEA/sCA 19–9) and paired peritoneal lavage CEA and CA 19–9 (pCEA/pCA 19–9) were measured in 90 patients with pancreatic cancer who underwent surgery. Using the cutoff values determined by maximally selected rank statistics for disease‐free survival (DFS), the risk of recurrence and its patterns were evaluated in combination with different markers and different test specimens.Results: In univariate and multivariate analysis, an elevated pCA 19–9 level (>1.3 U/mL) was an independent prognostic marker for both DFS (hazard ratio [HR], 2.391; P = .018) and overall survival (HR, 3.194; P = .033). Combination analyses contributed to further stratification of a very high risk of recurrence. Of the 58 patients with resectable pancreatic cancer who underwent curative resection, elevated pCA19–9 was also associated with inferior DFS and overall survival (OS). Patients with elevated pCA 19–9 levels were more likely to have an earlier onset of peritoneal recurrence than those with normal pCA 19–9 levels (P = .048, Gehan–Breslow–Wilcoxon test).Conclusion: pCA 19–9 is a reliable marker for predicting postoperative recurrence in patients with pancreatic cancer after surgery. Further risk stratification can be achieved by using combination assays. The combination of pCA 19–9 and sCA19–9 also serves as a predictor of recurrence site‐specific recurrence.