Carcinoembryonic antigen BEFORE AND AFTER neoadjuvant chemoradiotherapy IN PREDICTION OF pathological complete response in patients with locally advanced rectal cancer

Abstract

Carcinoembryonic antigen (CEA) is widely used to evaluate the effectiveness of treatment in patients with rectal cancer.The aim of the studywas to investigate whether the CEA levels measured before and after neoadjuvant chemoradiotherapy (nCRT) can be used to predict pathological complete response (pCR) in patients with locally advanced rectal cancer.Material and methods.179 patients with locally advanced rectal cancer were treated with nCRT followed by surgical treatment. The serum CEA level was measured before and 610 weeks after the completion of nCRT. Preand post nCRT CEA levels were compared with pCR. The factors associated with pCR were studied.Results.pCR after nCRT was achieved in 12 % (22/179) patients. The incidence of pCR was higher in patients with normal (<5 ng/mL) pre-treatment CEA level (20 %vs8 %, p=0.019). In patients with the elevated pre-treatment CEA level (> 5 ng/mL), there were no significant differences in the incidence of pCR between cases with normalization and without normalization of CEA level after treatment (p=0.08). The maximum likelihood of pCR determined by the ROC curve was <2.8 ng/mL with pre-treatment CEA (31 %) and <1.8 ng/mL with post-treatment CEA (23 %). Well differentiated tumors (G1) had higher likelihood of pCR (46%) in patients with low pre-treatment CEA (<2.8 ng/mL).Conclusion.Low CEA before and after nCRT is a predictor of pCR. Well differentiated tumors increase the probability of pCR after nCRT.