Preoperative staging of rectal and colonic cancer.

In rectal cancer, endosonography assesses the tumor penetration depth, EUS T1 to EUS T3, with a sensitivity of 96% and a specificity of 89%. The evaluation of lymph nodes is less accurate, at 79%. The surgical strategy is different in the three parts of the rectum, and depends on the endosonographic tumor stage: upper third of the rectum--anterior resection for all tumor stages; middle third of the rectum--EUS T1 N0: transanal endoscopic microsurgery for "low-risk" carcinomas; EUS T1-2: anterior resection; EUS T3: anterior resection with complete excision of the mesorectum, reconstruction with coloanal pouch; lower third of the rectum--EUS T1 N0: transanal endoscopic microsurgery for "low-risk" carcinomas; EUS T1-2: anterior or intersphincteric resection with complete excision of the mesorectum, reconstruction with colon pouch; EUS T3: abdominoperineal excision. With the impact of endosonography, the proportion of abdominoperineal excisions has dropped from 46% to 15% during the last five years. Laparoscopic technology is likely to have an increasing impact on surgical procedures that have previously required an open approach. The following treatment policy derived from the endosonographic staging of colon tumors is proposed: EUS T1, laparoscopic segmental resection; EUS T2, laparoscopic oncological resection; EUS T3, conventional open surgery.