A New Rectal Ultrasonographic Method for the Staging of Rectal Cancer

Abstract

Background: Radial transrectal ultrasound (R-TRUS) is the accepted method for rectal cancer staging. Accuracy rates fluctuate between 64% and 70% for T & N-staging. It is indicated in case of distal and non stenosing rectal tumors. The use of frontal probe may overcome the R-TRUS drawbacks. Aim: To compare the accuracy of transrectal ultrasound performed with a frontal probe (F-TRUS) to the classical radial probe (R-TRUS) in the preoperative T and N staging of rectal cancer. Patients and Methods: Seventy-four patients with biopsy proven rectal adenocarcinoma underwent both techniques at the same day. Thirty patients had the procedure after a neoadjuvant treatment. Staging accuracy of both methods were compared to surgical histopathology. Results: Forty-six men and 28 women were recruited. F-TRUS was performed in all the patients. Staging was amenable only in 58 patients with the R-TRUS because the tumors were either stenotic of too proximal. The F-TRUS was accurate in the T-staging of 89% of the tumors, while the R-TRUS reached only 69% (p=0.004). The difference was even more significant when we compared the accuracy among 58 patients in whom both examinations were completed (p=0.002). Both methods had similar accuracy for lymph node staging. Neoadjuvant treatment had no influence on accuracy. No overstaging was diagnosed with the F-TRUS. Understaging was more frequently encountered with the R-TRUS than with the F-TRUS (26% vs. 11%, p=0.036). Conclusions: As compared to R-TRUS, the F-TRUS has a better accuracy for T staging of rectal cancer. Its advantage in overcoming R-TRUS' drawbacks may make this procedure the method of choice for rectal cancer staging.