Operative versus nonoperative treatment for stage 0 distal rectal cancer following chemoradiation therapy - Habr-Gama, Angelita; Perez, Rodrigo Oliva; Nadalin, Wladimir; Sabbaga, Jorge; Ribeiro Junior, Ulysses; Sousa Junior, Afonso Henrique Silva e; Campos, Fábio Guilherme; Kiss, Desidério Roberto; Gama-Rodrigues, Joaquim (Annals of Surgery, 2004)