Intraoperative US Staging of T in gastric cancer. Final Results of a blind prospective study.

Abstract Background In order to improve the accuracy in the assessment of depth of tumor invasion, we performed an ultrasound examination of the resected specimen intraoperatively just after removal by the surgeon (Intraoperative Ultrasonography (IUS). This prospective blind study reports the results obtained with the IUS in the staging of T in a group of 281 patients who underwent curative gastrectomy for gastric cancer. Methods After the removal by the surgeon, the portion of the stomach harboring the tumor was submitted to ultrasonography with a linear 7.5 Mhz probe. An echo-free standoff pad was placed between the probe and the organ; a second echo-free standoff pad was interposed between the stomach and the support surface. The diagnosis of depth of invasion was based on the degree of disruption of the five-layer sonographic structure of the gastric wall. Results The IUS staging of T corresponded to the pathological diagnosis in 256 out of 281 cases (overall accuracy 91.1%). The sensitivity in the different classes of T was, respectively, 91.2 in T1m cases, 83.3 in the T1sm cases, 89.6 in the T2 cases, and 93.5% in the T3 cases. Conclusion The IUS on the resected specimen has a high degree of accuracy in the assessment of depth of tumor invasion and seems to be an important advance in the clinical staging of gastric cancer.