The significance of serum carcinoembryonic antigen in locally advanced rectal cancer treated by neoadjuvant chemoradiotherapy

Objective To investigate the significance of serum carcinoembryonic antigen (CEA) in locally advanced rectal cancer treated by neoadjuvant chemoradiotherapy. Methods A retrospective analysis was performed on the clinical data of 84 patients with rectal cancer, who underwent neoadjuvant chemoradiotherapy followed by radical surgery. The patients were all given the test of CEA level prior to and after the new adjuvant therapy. The relationship between CEA levels and pathological complate response (pCR) were assessed. Results In 84 patients, 18 (21.4%) achieved pCR after neoadjuvant chemoradiotherapy. The univariate analysis showed that circumferential extent of the tumor (≤1/2 cycle) (P=0.008), pre-chemoradiotherapy serum carcinoembryonie antigen (CEA) level (≤5 μg/L) (P=0.001), pre-chemoradiotherapy T stage (cT1-3) (P=0.001), pre-chemoradiotherapy N stage (P=0.049), distance between tumor and the anal verge (≤5 cm) (P=0.023) were associated with pCR or non-pCR after neoadjuvant chemoradiotherapy for rectal cancer. After neo-adjuvant therapy, more patients achieved pCR was observed in patients that CEA decreased ≥50%. Conclusion Patients with low CEA level are more likely to achieve pCR and patients with CEA decreased significantly are more likely to achieve greater pCR after neoadjuvant chemoradiotherapy for rectal cancer. Key words: Rectal cancer; Carcinoembryonic antigen; Neoadjuvant chemoradiotherapy; Pathological complete response