Early response evaluation using CT and CA 19-9 in patients with pancreatic cancer of all stages undergoing first-line FOLFIRINOX treatment.

Objectives: To propose an effective integration method for CT and carbohydrate antigen (CA) 19-9 responses applicable to patients with all stages of pancreatic ductal adenocarcinoma (PDAC) treated with first-line FOLFIRINOX.

Methods: We retrospectively identified patients with PDAC who underwent first-line FOLFIRINOX treatment at a single tertiary hospital between 2017 and 2020. Those with baseline and 8-week follow-up CT scans were included in the CT response dataset. Patients with both CT and CA 19-9 information comprised the CT/CA 19-9 response dataset. CT reports and CA 19-9 levels at baseline and 8-week follow-up were collected. CT response was based on Response Evaluation Criteria in Solid Tumors. CA 19-9 changes were determined as CA 19-9 levels normalized (<37 U/mL), decreased (>37 U/mL), or increased. Overall survival (OS) was compared.

Results: In the CT response dataset (n = 392), patients with progressive disease (PD; n = 44) exhibited shorter OS than stable disease (SD; n = 228; P = .01) or partial response (PR; n = 120; P = .001). OS did not significantly differ between PR and SD (P = .40). In the CT/CA 19-9 response dataset (n = 242), integrated CT and CA 19-9 responses revealed the shortest OS in patients with either PD or increased CA 19-9 (n = 74; median OS, 14.3 months), followed by PR/SD with decreased CA 19-9 (n = 113; median OS, 19.8 months; P = .003), and PR/SD with normalized CA 19-9 (n = 55; median OS, 23.6 months; P = .04).

Conclusion: Our combined evaluation of CT and CA 19-9 responses successfully stratified the survival of patients with PDAC treated with FOLFIRINOX, irrespective of disease stage.