Anal carcinoma: prognostic value of endorectal ultrasound (ERUS). Results of a prospective multicenter study.

ABSTRACT

BACKGROUND AND STUDY AIMS: The classification of anal carcinoma is based on the clinical examination and the estimation of the tumor height (Union Internationale Contre le Cancer (UICC) 1987 Classification). This classification has a direct therapeutic application since tumors which are designated T1 and T2 are generally treated by radiotherapy whereas T3, T4 or N+ lesions are treated by concomitant radiation and chemotherapy. The aim of this prospective multicenter study was to evaluate endorectal ultrasound (ERUS) and to define an ERUS-based classification. PATIENTS AND METHODS: Between January 1994 and May 1997, 146 patients (42 men and 104 women; mean age, 63) from eight different centers were studied prospectively. The ERUS classification incorporates disease of the anal canal and the perirectal lymph nodes, thus usT1 describes involvement of the mucosa and submucosa with sparing of the internal sphincter; usT2, involvement of the internal sphincter with sparing of the external sphincter; usT3, involvement of the external sphincter; usT4, involvement of a pelvic organ; N0 describes no suspicious perirectal lymph nodes, and N+, perirectal lymph nodes fulfilling endosonographic criteria for malignancy (e.g. round, hypoechoic). Tumors classified as UICC T1-T2 (<4cm) N0 were treated by radiotherapy alone, whereas lesions with a UICC classification of T2 (> 4 cm), T3-T4, N0-N1-2-3 received combined radiochemotherapy. RESULTS: Data concerning the treatment and follow-up were available for 115/146 patients (78.7%). We compared the prognostic importance of the two classification schemes for treatment response and the rate of local relapse (chi-squared test). A significantly greater proportion of T1-T2N0 lesions classified by ERUS had a complete response to treatment than those classified by conventional UICC staging (94.5% vs. 80%, respectively; P = 0.008). The ERUS T and N stage were significant predictors of relapse (P=0.001 and P=0.03, respectively) whereas the corresponding clinical (UICC) stages were not (P = 0.4 and P = 0.5, respectively). Using a Cox model, usT stage was the only significant predictive factor for patient survival. CONCLUSION: This muticenter prospective study demonstrated the superiority of ERUS-based staging over traditional clinical staging in the prediction of important outcomes such as local tumor recurrence and patient survival.