Substaging of T1 bladder carcinoma based on the depth of invasion as measured by micrometer - A new proposal

BACKGROUND, A significant number of T1 bladder carcinoma patients are under staged by transurethral resection of the bladder (TURB), indicating a subst antial need for more accurate staging. METHODS. The authors studied 55 patients with T1 bladder carcinoma detected by TURB at the Mayo Clinic between December 1979 and July 1984. The mean a ge of the patients was 66 years (range, 50-78 years). All patients were tre ated by cystectomy. The median interval from TURB to cystectomy was 10 days . Grading was performed according to the 1998 World Health Organization/Int ernational Society of Urologic Pathology grading system. The 1997 TNM class ification was used for pathologic staging. In addition, the depth of invasi on was measured from the mucosal basement membrane by micrometer. Receiver operating characteristic (ROC) analysis was used to evaluate the usefulness of depth of invasion asa marker for advanced stage bladder carcinoma (grea ter than or equal to T2). RESULTS, The final pathologic stages were Ta (2 patients), T1 (10 patients) , T2a (9 patients), T2b (13 patients), T3 (11 patients), and T4 (10 patient s) at cystectomy. There was a significant correlation between the depth of invasion at TURB and the final pathologic stage (Spearman correlation coeff icient = 0.63; P < 0.001). The overall accuracy for the prediction of advan ced stage (greater than or equal to T2) bladder carcinoma as measured by th e area under the ROC curve was 0.89 (standard error, 0.05). Using 1.5 mm as a threshold (with >1.5 mm indicating advanced stage disease), the sensitiv ity, specificity, and positive and negative predictive values were 81%, 83% , 95%, and 56%, respectively, Histologic grade at the time of TURB also was associated significantly with final pathologic stage at cystectomy (P = 0. 03) whereas stratification of patients according to invasion above or below the muscularis mucosae at TURB tvas not a significant predictor of final p athologic stage. CONCLUSIONS, The results of the current study show that substaging of T1 bl adder carcinoma according to the depth of invasion (as measured by micromet er) provides significant prognostic information. Therefore the authors reco mmend that it be reported in specimens obtained by TURB. (C) 1999 American Cancer Society.