ASSESSMENT OF TUMOR INFILTRATION DEPTH IN RECTAL-CANCER WITH TRANSRECTAL SONOGRAPHY - CAUTION IS NECESSARY

PURPOSE: To assess the depth of infiltration of rectal cancer with tra nsrectal ultrasound (US) (TRUS) and analyze interpretation errors. MAT ERIALS AND METHODS: Fifty-five consecutive patients with rectal cancer who underwent TRUS were prospectively studied. The effect of differen t patient inclusion criteria and US criteria was evaluated retrospecti vely. RESULTS: Extensive overstaging of T2 tumors, partially caused by inflammatory (desmoplastic) reaction or retraction of the muscularis propria, resulted in a specificity of only 24% for detection of perire ctal infiltration. Sensitivity was 97%, and accuracy was 64%. Consider able variation in staging accuracy was observed when different patient selection criteria were used. Variation of US criteria improved diffe rentiation between T2 and T3 tumors only slightly. CONCLUSION: The eff ect of different US criteria on differentiation of T2 and T3 tumors is limited. Spontaneous or iatrogenic inflammation is a major limiting f actor. The accuracy of TRUS in staging rectal cancer is affected by pa tient inclusion criteria.