Tumor size predicts the survival of patients with pathologic stage T2 bladder carcinoma: A critical evaluation of the depth of muscle invasion

BACKGROUND. Accurate examination of radical cystectomy specimens is critical for stratifying patients into prognostically important groups and determining the need for adjuvant treatment. Evidence has accumulated that cancers invading the superficial muscle wall (T2a) behave similarly to those invading the deep muscle wall (T2b). Quantitative analysis of the depth of invasion in relation to patient outcome is needed. METHODS. The authors systematically evaluated the depth of invasion by micrometer measurement and its relation to the survival of 64 patients with bladder carcinoma pathologic classification as pT2 who had long term follow-up after radical cystectomy. Numerous clinical and pathologic variables were analyzed with univariate and multivariate Cox proportional hazards models. The mean age of patients was 64 years, and their mean follow-up was 8.3 years. RESULTS. There was no significant difference in clinical outcome between patients with T2a carcinoma and those with T2b. Lymph node metastasis and tumor size were each significantly associated with distant metastasis free and cancer specific survival. Ten-year distant metastasis free and cancer specific survival were 100% and 94%, respectively, for patients with tumors <3 cm (P = 0.006) and 68% and 73%, respectively, for patients with tumors ≥3 cm (P = 0.005). After adjustment for lymph node status, tumor size maintained significance in predicting distant metastasis free survival (risk ratio, 1.5; 95% confidence interval, 1.1-2.0; P = 0.009) and cancer specific survival (risk ratio, 1.5; 95% confidence interval, 1.1-1.9; P = 0.01). Age was associated with recurrence free survival and all-cause survival. None of the other variables, including gender, vascular invasion, presence of carcinoma in situ, pathologic classification (T2a vs. T2b), depth of invasion, depth of muscle invasion, ratio of depth of invasion to bladder wall thickness, and percentage of muscle wall invasion, were significantly associated with patient outcome. CONCLUSIONS. The findings of this study indicate that the subclassification of T2 bladder carcinoma by depth of muscle invasion is of no prognostic value; conversely, tumor size, an easily measured factor, is predictive of distant metastasis free and cancer specific survival.