CEACAM5 and rectal cancer: Few studies have reported some conflicting result of clinical predictive factors for pCR, including tumor size,[13] tumor size from calculation by volumetry method,[14] nodal stage,[15] and pretreatment carcinoembryonic antigen (CEA) level.[16] Tumor length, as measured by computerized tomography scan or magnetic resonance imaging, is one of the routine clinical parameters collected in management of rectal cancer.