CEACAM5 and rectal cancer: However, it is known that aside from embryological, anatomical, and physiological differences between the colon and rectum, colon and rectal cancer seem to differ in oncogenesis.19 Thus, the aim of the present study was to elucidate the further clinicopathologic significance of increase in pretreatment serum CA19-9 and test the hypothesis that the combination of preoperative CEA and CA19-9 serum levels could be more sensitive and specific in prediction of survival in locally advanced rectal cancer following neoadjuvant chemoradiotherapy (neo-CRT).