Predictive Factors for Occult Metastases in Clinically M0 Pancreatic Cancer: A Prospective Multicenter Analysis of Staging Laparoscopy

BACKGROUND: Staging laparoscopy (SL) is a minimally invasive approach for detecting occult metastases in patients with pancreatic cancer (PC) without signs of metastasis on imaging. This study aimed to identify the predictive factors for imaging-negative occult metastases. METHODS: This prospective study enrolled 199 patients with histologically confirmed PC from three institutions between August 2021 and April 2023. All patients were scheduled for a treatment plan that included SL. RESULTS: The overall metastasis rate as detected using SL was 25.1%, which varied from 20.6% in patients with resectable PC (R-PC) to 33.8% in those with borderline resectable or locally advanced unresectable PC (BR/URLA-PC). In 152 patients who did not receive neoadjuvant therapy, BR/URLA status (odds ratio 3.261; 95% confidence interval 1.185-9.483, p = 0.022) and pancreatic body/tail lesions (odds ratio 2.653; 95% confidence interval 1.037-7.214, p = 0.042) were independent risk factors for occult metastatic lesions (M1). Among the 107 patients with R-PC, M1 disease was significantly associated with pancreatic body/tail lesions, tumor size, and elevated levels of tumor markers. In particular, elevated carbohydrate antigen 19-9 levels were consistent across all patients with M1 pancreatic head cancer. In contrast, no statistical differences were observed for any of these factors in the 45 patients with BR/URLA-PC. CONCLUSIONS: Our findings support the importance of SL in patients with BR/UR PC. For R-PC, patients with pancreatic head lesions and normal tumor marker values may represent a very low-risk subgroup where selective omission of SL can be considered in resource-constrained settings.