Tumor regression grading after preoperative chemoradiotherapy for locally advanced rectal carcinoma revisited: updated results of the CAO/ARO/AIO-94 trial. by Fokas, E, Liersch, T, Fietkau, R, Hohenberger, W, Beissbarth, T, Hess, C, Becker, H, Ghadimi, M, Mrak, K, Merkel, S, Raab, H, Sauer, R, Wittekind, C, Rödel, C