Combining prognostic value of serum carbohydrate antigen 19-9 and tumor size reduction ratio in pancreatic ductal adenocarcinoma

BACKGROUND Pancreatic ductal adenocarcinoma (PDAC) is a common cancer with increasing morbidity and mortality due to changes of social environment. AIM To evaluate the significance of serum carbohydrate antigen 19-9 (CA19-9) and tumor size changes pre- and post-neoadjuvant therapy (NAT). METHODS This retrospective study was conducted at the Chongqing Key Laboratory of Translational Research for Cancer Metastasis and Individualized Treatment, Chongqing University Cancer Hospital. This study specifically assessed CA19-9 levels and tumor size before and after NAT. RESULTS A total of 156 patients who completed NAT and subsequently underwent tumor resection were included in this study. The average age was 65.4 10.6 years and 72 (46.2%) patients were female. Before survival analysis, we defined the post-NAT serum CA19-9 level/pre-NAT serum CA19-9 level as the CA19-9 ratio (CR). The patients were divided into three groups: CR < 0.5, CR > 0.5 and < 1 and CR > 1. With regard to tumor size measured by both computed tomography and magnetic resonance imaging, we defined the post-NAT tumor size/pre-NAT tumor size as the tumor size ratio (TR). The patients were then divided into three groups: TR < 0.5, TR > 0.5 and < 1 and TR > 1. Based on these groups divided according to CR and TR, we performed both overall survival (OS) and disease-free survival (DFS) analyses. Log-rank tests showed that both OS and DFS were significantly different among the groups according to CR and TR (P < 0.05). CR and TR after NAT were associated with increased odds of achieving a complete or near-complete pathologic response. Moreover, CR (hazard ratio: 1.721, 95%CI: 1.373-3.762; P = 0.006), and TR (hazard ratio: 1.435, 95%CI: 1.275-4.363; P = 0.014) were identified as independent factors associated with OS. CONCLUSION This study demonstrated that post-NAT serum CA19-9 level/pre-NAT serum CA19-9 level and post-NAT tumor size/pre-NAT tumor size were independent factors associated with OS in patients with PDAC who received NAT and subsequent surgical resection.