Preoperative staging of colorectal cancer by a 15 MHz ultrasound miniprobe

Abstract Background: Our objective was to examine the accuracy of a 15 MHz ultrasound miniprobe in the preoperative staging of colorectal cancer by assessing the depth of tumor infiltration and involvement of pericolonic lymph nodes. Methods: Thirty-three patients with colorectal cancer who underwent ultrasonography with a miniprobe were studied prospectively. The results of this imaging were compared with the histologic findings of the resected specimens. Results: The accuracy of the miniprobe for depth of invasion (T category) was 82% (27 of 33) for all tumors, 76% (13 of 17) in pT1 cases, and 88% (14 of 16) in pT2 to pT4 cases. The accuracy of the miniprobe for nodal staging (N category) was 87% (26 of 30) overall. The sensitivity was 63% (5 of 8), the specificity was 95% (21 of 22), the positive predictive value was 83% (5 of 6), and the negative predictive value was 88% (21 of 24). Conclusions: The miniprobe is an accurate method for the preoperative TN staging of colorectal cancer. We recommend its preoperative use because the results may influence the surgical approach. (Surgery 1998;123:264-9.)