Intraoperative decision-making for pancreatic ductal adenocarcinoma with occult para-aortic lymph node metastasis: Proposal of a pathology-based weighted risk scoring system.

BACKGROUND: Para-aortic lymph node (PALN) metastasis in pancreatic ductal adenocarcinoma (PDAC) is generally considered unresectable. However, resection for PDAC with PALN metastasis diagnosed by intraoperative sampling remains controversial. This study aimed to develop a risk scoring system for intraoperative decision-making regarding PDAC resection. METHODS: Between 2005 and 2021, 60 patients with PALN metastasis diagnosed by intraoperative sampling were analyzed. Six pathological factors were evaluated in sampled PALNs: maximum lesion size, number of lesions, lesion localization, histological grade, desmoplastic reaction, and extranodal extension. Weighted scores were assigned using β coefficients derived from the Cox proportional hazards regression model. RESULTS: Histological grade G3 scored 3 points; maximum lesion size >2.0 mm, ≥3 lesions, and intranodal localization scored 2 points; desmoplastic reaction and extranodal extension scored 1 point. A cut-off score of 4 by 2-year time-dependent receiver operating characteristic curve analysis stratified patients into high- and low-risk groups. Patients were categorized into low-risk/resection (n = 20), low-risk/no-resection (n = 4), high-risk/resection (n = 22), and high-risk/no-resection (n = 14). Overall survival was significantly better in the low-risk/resection group than in the low-risk/no-resection group (p = 0.003), whereas there was no significant difference between the high-risk/resection and high-risk/no-resection groups (p = 0.603). Multivariable analysis identified pathological findings in the sampled PALNs (Hazard ratio = 2.463, p = 0.021) as an independent prognostic factor in 42 patients who underwent resection. CONCLUSION: The weighted risk scoring system may enable objective intraoperative decision-making and treatment optimization.