Staging of colonic neoplasms by colonoscopic miniprobe ultrasonography

In contrast to the situation in the upper gastrointestinal tract staging of colonic neoplasm by endoscopic ultrasonography (EUS) has not gained importance because until yet preoperative staging is without any clinical consequences. This may change with the introduction of minimally invasive surgical procedures and endoscopic resection techniques as an alternative to conventional (open) surgery.

We performed EUS with a miniprobe in 54 consecutive patients with colonic tumors who had been referred to our hospital for endoscopic resection or for laparoscopic resection of their lesions. Therefore patients with locally advanced tumors or systemic tumor spread were not included. After detection of the lesion during colonoscopy miniprobe EUS was performed with water-filling of the colonic lumen. The depth of invasion (T classification) and the local lymph node status (positive or negative) was ascertained. Lymph node-negative lesions staged as T1 underwent endoscopic resection whenever this was technically possible. In lymph node-negative T2-3 tumors laparoscopic resection was planned if they were localized at least 10 cm apart from the flexuras. All other lesions were resected by open surgery. The EUS findings were later compared with the final pathological results (pTN classification) of the resected specimen.

In 50 patients (93%) a sufficient EUS evaluation of the colonic tumor was possible. In one patient with a tumor at the left flexura the lesion could not be completely visualized, and in three patients a sufficient water filling of the colon was impossible. The infiltration depth was correctly classified in 17 adenomas, 16 T1, 8 T2, 5 T3, and one T4-carcinoma (EUS accuracy for T staging: 94%). Two T2 and one T3 carcinoma were overstaged by EUS while no understaging was recorded. The lymph node status was correctly classified in 42/50 patients (84%), and a false-negative lymph node status was found in only 4/50 cases (8%). The overall accuracy of EUS was 80%.

Miniprobe EUS is suitable and has a sufficient but not optimal accuracy for staging of colonic neoplasm. Its employment makes sense if minimally invasive resection techniques in patients with high-risk for open surgery are planned.