High Expression of P38α and Preoperative Carbohydrate Antigen 19-9 Indicate Poor Prognosis in Patients with Pancreatic Ductal Adenocarcinoma

Background: P38α is a ubiquitous protein kinase, which plays diverse roles in cancers. Surprisingly, P38α functions vary markedly in different cancers (e.g., cancer suppressor vs cancer promoter). However, there is no report on the expression of P38α, the family's most important member, in pancreatic ductal adenocarcinoma (PDAC) and its association with clinicoathological parameters and patients' prognosis. Materials and methods: We retrospectively analyzed 152 patients who underwent surgery and were pathologically diagnosed with PDAC from September 2013 to September 2015. We used immunohistochemistry to detect P38α expression in tumor and adjacent normal tissues. The significance of the association between P38α and clinicopathological parameters was evaluated using the χ² test and t tests. The Kaplan-Meier method was used to assess the association between P38α expression and preoperative carbohydrate antigen 19-9 (CA19-9) levels and patients' overall survival. The Cox regression model was used to analyze the association between clinicopathological parameters, P38α and preoperative CA19-9 levels, and prognosis. Statistical significance was defined as P < 0.05. Results: P38α was expressed in 63.16% tumor tissues of PDAC, which was significantly higher compared with the adjacent normal tissues (26.32%, P < 0.001). High expression of P38α was associated with patients' histological grade (P = 0.013), lymphatic metastasis (P = 0.025) and TNM stage (P = 0.048). The median survival time of the P38α-high group was 9.2 months, which was shorter compared with that of the P38α-low group (17.3 months, P = 0.011). The median survival time of the CA19-9 > 43.63 group was 11.1 months shorter than that of the CA19-9 < 43.63 group (24.8 months, P < 0.001). The Cox regression model revealed that age (P = 0.003), lymphatic invasion (P = 0.015), TNM stage (P = 0.003), histological grade (P < 0.001), preoperative CA19-9 (P = 0.049), and P38α expression (P = 0.008) were statistically significant independent risk factors affecting prognosis. Specifically, overall survival was 28.4 months in the P38α-low and CA19-9 < 43.63 groups, 16.3 months in the P38α-high or CA19-9 > 43.63 groups, and 9.7 months in the P38α-high and CA19-9 > 43.63 groups (P < 0.001). Conclusions: High expression of P38α was significantly associated with histological grade, lymphatic metastasis, TNM stage and prognosis in patients with PDAC. P38α and preoperative CA19-9 levels were independent risk factors affecting the prognosis of PDAC patients. High expression of p38α and preoperative carbohydrate antigen 19-9 indicate poor prognosis in patients with PDAC.