Abstract 2399: Stage-matched prognosis comparison between ypTNM and pTNM stage in pancreatic cancer

Abstract Introduction: The prognostic significance of pathological stage in pancreatic cancer is well-established. The 8th American Joint Commission on Cancer (AJCC) TNM staging introduced the ypTNM stage for neoadjuvant treatment (NAT) patients responding to the increased use of NAT. Despite this, there has been no comparative assessment of the prognosis between ypTNM and pTNM stages in pancreatic cancer. This study aimed to evaluate and compare the prognoses between ypTNM and pTNM stages in surgically resected pancreatic cancer. Method: A cohort of 586 patients who underwent pancreatic cancer surgery at a tertiary center from January 2018 to March 2022 was analyzed. Exclusions comprised those with prior pancreatectomy, suspicious liver metastasis or peritoneal seeding before NAT, those with open biopsy, R2 resection, and distant metastasis during operation, and postoperative mortalities or immediate follow-up losses. Clinicopathologic demographics underwent analysis, and a propensity score-matched (PSM) analysis (1:3) was conducted based on factors influencing overall survival (OS) in multivariate analysis. Subgroup analyses, categorized by stage, compared survival between ypTNM and pTNM stages. Results: The analysis included 541 patients, with 100 undergoing NAT (ypTNM) and 441 opting for upfront surgery (pTNM). Comparable OS was observed between ypTNM and pTNM patients (median 51.0 vs. 46.0 months, 3-year survival rate (YSR) 68.7% vs 56.3%, p = 0.094). Subgroup analysis by stages I (3YSR 76.8% vs 67.5%, p = 0.577), II (56.2% vs 53.0%, p = 0.715), and III (26.5% vs 28.7%, p = 0.596) revealed similar survival between ypTNM and pTNM. Multivariate analysis identified factors such as age >65 (HR 1.651, p = 0.002), CA19-9 >150 (HR 1.476, p = 0.010), preoperative biliary drainage (HR 1.372, p = 0.048), pathologic T2 stage (HR 2.188, p = 0.002) and T3, 4 stage (HR 3.178, p < 0.001) compared to T0, 1 stage, lymphovascular invasion (HR 2.087, p < 0.001), and adjuvant treatment (HR 0.243, p < 0.001) associated with OS. After PSM analysis, stages I (3YSR 76.8% vs 71.7%, p = 0.923), II (56.2% vs 46.6%, p = 0.886), and III (26.5% vs 31.4%, p = 0.856) exhibited no significant difference in OS between ypTNM and pTNM stages. Conclusions: Our study underscores comparable survival outcomes between ypTNM and pTNM stages in surgically resected pancreatic cancer, affirming the applicability of the TNM staging system after NAT. Consistent survival results, even following PSM analysis, highlight the reliability of TNM staging for guiding therapeutic decisions even in patients with NAT. Citation Format: Hyeong Seok Kim, Hochang Chae, Soo Yeun Lim, Hye Jeong Jeong, So Jeong Yoon, Sang Hyun Shin, In Woong Han, Jin Seok Heo, Hongbeom Kim. Stage-matched prognosis comparison between ypTNM and pTNM stage in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2399.