Validation of the AJCC TNM Substaging of pT2 Bladder Cancer: Deep Muscle Invasion Is Associated with Significantly Worse Outcome

Background: The current TNM bladder cancer staging system stratifies bladder muscle invasion into superficial (pT2a) and deep (pT2b). Controversy exists regarding the significance of the extent of muscle invasion on clinical outcome. Objective: Our aim was to compare the cancer-specific outcomes of patients with pT2 urothelial carcinoma of the bladder (UCB) at radical cystectomy (RC) in a large international cohort of patients. Design, setting, and participants: The records of patients treated with RC for UCB at six centers were reviewed. Of the 2605 reviewed patients, 565 (21.7%) had pT2 disease. None of the patients received preoperative systemic chemotherapy or radiotherapy. Measurements: Patients' characteristics and outcome were evaluated. Results and limitations: The median patient age in the entire group was 66.2 yr. Of the 565 patients with pT2 UCB, 249 patients (44.1%) had substage pT2a; 316 patients (55.9%) had pT2b. One hundred and eleven patients (19.6%) had metastases to regional lymph nodes. Median follow-up was 50.5 mo. Recurrence-free survival (73.2% vs 58.7%) and cancer-specific survival (78.0% vs 65.1%) estimates were significantly better for pT2a patients compared with those with pT2b (p = 0.002 and p = 0.001, respectively). Pathologic T2 substaging was associated with worse recurrence-free and cancer-specific survival after adjusting for the effects of standard pathologic features (p = 0.011 and p = 0.006, respectively). The statistical significance of these associations was reconfirmed in subgroup analysis limited to those patients with pathologically negative lymph nodes. Conclusions: In this large international cohort, pathologic substaging helped to stratify patients with lymph node-negative pT2 UCB into statistically significantly different risk groups. These data support the value of the current American Joint Committee on Cancer TNM staging.