Individualized Cutoff Value of the Serum Carcinoembryonic Antigen Level According to TNM Stage in Colorectal Cancer

levels of ≥4 ng/mL vs. <4 ng/mL, the relative risk was 1.4 (P < 0.07). The 2-year survival rates in the groups of patients with preoperative serum CEA levels >4 ng/mL and <4 ng/mL were 16% and 38%, respectively, for patients with Dukes’ stage D cancer, 73% and 91% for patients with Duke’s stage B/C cancer, and 100% and 98% for patients with Dukes’ stage A cancer. Also, Takagawa et al. [2] reported that the relapse-free survival was significantly different in patients with stage II and III according to preoperative CEA level (>10 ng/mL vs. <10 ng/mL). However, in patients with stage I, there was no significant difference in relapse-free survival. Park et al. [9] divided patients with colorectal cancer into four subgroups by using serum CEA cutoff values of 3, 6, and 17 ng/mL. Their 5-year disease free survival rates were 85.3% (<3.0 ng/mL), 70.0% (3–6 ng/mL), 64.2% (6–17 ng/mL), and 55.2% (>17 ng/mL) (P < 0.001). According to stage, a significant difference in survival was observed only in patients with stage III tumors (P = 0.007). In this study, the authors tried to determine the individual optimal cutoff value of CEA according to TNM stage [10]. The conventional cutoff value of CEA (5 ng/mL) has no significant prognostic value in stage T1–2, N0 and stage T1–4, N2. Optimal cutoff values from the receiver operating characteristic curve were 7.4, 5.5 and 4.5 ng/mL for TNM stages I, II and III, respectively. Those for stages N0, N1 and N2 were 5.5, 4.8 and 3.5 ng/mL, respectively. The 5-year disease free survivals were significantly different with these cutoff values for each TNM and N stages. However, one has to consider that a sub-normal CEA level may be a cutoff value that can be used as a prognostic marker.