The study population was patients (n = 574, 67.1 +/- 11.3 years old, 397 males) who received potentially curative resection of colorectal adenocarcinoma (stage I-III) between January 1994 and August 2002, including preoperative measurements of CEA and CA19-9. Clinicopathological characteristics and associated follow-up data were retrospectively collected by reviewing available medical charts. CEA higher or equal to 5 ng/ml was defined as abnormal (CEA+). The CA19-9 level was set at 37 U/ml (CA19-9+)