Clinical significance of pre- to post-chemoradiotherapy s-CEA reduction ratio in rectal cancer patients treated with preoperative chemoradiotherapy and curative resection.

PURPOSE: To evaluate the clinical significance of a reduction in serum carcinoembryonic antigen (s-CEA) concentration ratio from before to after preoperative chemoradiotherapy (CRT) in terms of recurrence and prognostic factors in rectal cancer patients.
METHODS: We retrospectively evaluated 333 rectal cancer patients who received preoperative CRT followed by surgery with curative intent between January 2000 and December 2006. Patients were divided into three groups: those with pre-CRT s-CEA≤6 ng/mL (group 1), those with pre-CRT s-CEA>6 mg/mL and post-CRT s-CEA≥70% lower than pre-CRT s-CEA (group 2), and those with pre-CRT s-CEA>6 mg/mL and post-CRT s-CEA<70% lower or higher than pre-CRT s-CEA (group 3).
RESULTS: The 5-year disease-free survival rate was similar in group 1 (76.0%) and group 2 (66.0%), but significantly lower in group 3 (39.5%) (p<0.001). Multivariate analysis showed that CEA group 3, ypT stage, ypN stage, and type of surgery were independent prognostic factors for disease-free survival.
CONCLUSIONS: The reduction ratio of pre- to post-CRT s-CEA concentration may be an independent prognostic factor for disease-free survival following preoperative CRT and surgery in rectal cancer patients with initial s-CEA>6 ng/mL.