Value Of Miniature Endoscopic Ultrasound In The Preoperative Staging Of Rectal Cancer

ObjectiveTo evaluate the value of miniature endoscopic ultrasound (MUP) in the preoperative staging of rectal cancer.Methods71rectal cancer patients were enrolled and all underwent EUS with mini probe of12MHz before surgery. The pictures of the EUS were collected for staging by a sonographer doctor, who was blinded to the pathologic results, according to the newest version7UICC TNM staging system. The EUS results were compared with the pathologic results.ResultsThe overall concordance rates of12MHz MUP in T staging was72%(51/71). The accuracy, sensitivity and specificity of T staging were82%,46%,100%for T1tumors, 76%,92%,68%for T2tumors,90%,78%,93%for T3tumors and95%,78%,98%for T4tumors, respectively. The sensitivity and specificity of T staging for early cancer (Tl)46%,100%, respectively. There were21%(15/71) overstaged, while7%(5/71) were understaged in T staging. The overall concordance rates in N staging was73%(52/71). The accuracy, sensitivity and specificity were73%,93%,12%for NO tumors,83%,20%,93%for Nl tumors,90%,0,100%for N2tumors, respectively.6%(4/71) tumors were overstaged and21%(15/71) tumors were understaged in N staging. T staging concordance rates for low rectal tumors (0-6cm from the anal verge) was68%(30/44), whereas74%(17/23) and100%(4/4) of mid (7-12cm) and high (>12cm) tumors were staged correctly, respectively. The differences were not statistically significant,as well as for the low versus the mid and high rectal tumors. The concordance rates was57%for large tumors (>2cm), which was lower than73%for small tumors (<2cm). Differences did not reach statistical significance.ConclusionMUP is an accurate technique for preoperative TN staging, with different concordance rates but no statistically significant differences as the distance of tumors from the anal verge and tumors size vary. The specificity was very high for T1tumors(early rectal cancer), while the sensitivity for node positive yet needs to be improved. More experienced operators, and choosing lower frequency standard probe when making diagnoses for large lesions or lymph nodes, as well as EUS-FNA may make MUP more accuracy.