Concordance and survival implications of preoperative subclassification of T3 rectal cancers by depth of mesorectal invasion using a 5-mm cut-off point with endorectal ultrasound and magnetic resonance imaging.

BACKGROUND: Validated rectal cancer staging groups T3 tumours in a single stage and depth of mesorectal invasion subclassification is not standard practice. Our aim is to report concordance between magnetic resonance imaging (MRI) and endorectal ultrasound (ERUS) for preoperative staging of T3 rectal tumours using a 5-mm cut-off point and possible survival implications. METHODS: Prospective cohort study including patients staged preoperatively as cT3 by ERUS or magnetic resonance imaging. The maximum depth of penetration beyond the outer longitudinal muscle layer was measured according to a 5-mm cut-off point. Concordance rate and Kappa coefficient were calculated for both techniques. Prima…