[Rectal cancer staging with endoscopic ultrasonography: correlation with pathological staging].

OBJECTIVE

our aim was to evaluate the accuracy of endosonography (EUS) in our experience, to stage rectal cancer.

MATERIAL AND METHODS

we prospectively included all patients with rectal cancer staged in our unit from September 2002 until February 2006 in a database. We selected those patients who had a complete EUS examination and were surgically treated without neoadjuvant therapy. Once we had the results of the histopathological staging (pTN), which was considered the gold standard, we compared the results of the previous EUS staging (uTN) with those of the pTN. We calculated the sensitivity, specificity, positive predictive value, negative predictive value and accuracy for each T stage, and for N staging considered as N positive or negative. We also calculated the global accuracy for T stage. We also calculated the agreement of uTN with pTN staging using the kappa index for N stage, and quadratic weighted kappa index for T stage.

RESULTS

we staged 120 patients with rectal cancer during the mentioned period. Of these, 36 patients met inclusion criteria and were evaluated, 21 women and 15 men. Mean age was 68,53+/-10,15 yo (range: 48-90). Global T stage accuracy was 83%. N stage accuracy was 72%. We obtained a S, E, PPV, NPV and A of 91, 100, 100, 96 and 97% for T1; 82, 88, 75, 91 and 86% for T2; 86, 91, 86, 91 and 89% for T3; and 14, 86, 20, 80 and 72% for N stage respectively. Kappa value for T stage was 0,87 indicating a "very good" agreement between uT and pT according to the kappa index criteria. Kappa value for N stage agreement was 0,005; "poor" according to the same criteria.

CONCLUSIONS

in our experience, the diagnostic accuracy of EUS for T and N staging of rectal cancer is 83% and 72% respectively, similar results as previously published. uT staging for rectal cancer shows a "very good" agreement with pT staging.