“…Nevertheless, up to 15% of patients with pancreatic cancer are found unresectable at the time of surgery, which is attributable to occult vascular invasion, presence of undetected metastasis or positive peritoneal lavage cytology [25]. Whether preoperative CA 19-9 serum levels can serve as a surrogate marker for tumor resectability has been extensively evaluated [22,25,26,[29][30][31][32][33][34][35][36] (Table 3). Schleiman et al evaluated preoperative CA 19-9 serum levels in 89 pancreatic cancer patients prior to surgical exploration and noted that mean CA 19-9 serum levels were significantly lower in resectable tumors compared to those with locally advanced tumors (63 vs. 592 U/ml, p<0.003) or with metastatic disease (63 vs. 1,387 U/ml, p<0.001) [32] (Table 3).…”