Clinical significance of serial serum carcinoembryonic antigen values for treating rectal cancer with preoperative chemoradiotherapy.

Objective: Preoperative chemoradiotherapy is now widely accepted to treat rectal cancer; however, the prognosis for rectal cancer patients during and after chemoradiotherapy must be determined. The aim of this study was to evaluate the serial serum carcinoembryonic antigen (s-CEA) samples in patients with rectal cancer who underwent radical surgery after concurrent chemoradiotherapy (CRT).

Methods: This study evaluated 236 patients with rectal cancer who received preoperative CRT followed by curative surgery between June 2005 and June 2010. We measured the patient's s-CEA levels pre-CRT, post-CRT and post-surgery. Patients were classified into four groups according to their s-CEA concentrations (group 1, high, high, high; group 2, high, high, normal; group 3, high, normal, normal; group 4, normal, normal, normal). We analyzed the clinicopathologic factors and the outcomes among these groups.

Results: Of the 236 patients, 12 were in group 1, 31 were in group 2, 67 were in group 3, and 126 were in group 4. The 3-year disease-free survival rate in group 1 was poorer than those in group 3 (P = 0.007) and group 4 (P < 0.001). In a univariate analysis, type of surgery, clinical N stage, pathologic T or N stage, lymphovascular invasion, perineural invasion, and CEA group were prognostic factors. A multivariate analysis revealed that type of surgery, pathologic T stage, and lymphovascular invasion were independent prognostic factors; however, no statistical significance was associated with the CEA group.

Conclusions: High pre-CRT, post-CRT, and post-surgery s-CEA levels in patients with rectal cancer were associated with high rates of systemic recurrence and poor survival. Therefore, patients with sustained high s-CEA levels during CRT require careful monitoring after surgery.