['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.', '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.', '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.', "Patients' characteristics and outcome were evaluated."] Is validation of the AJCC TNM substaging of pT2 bladder cancer : deep muscle invasion associated with significantly worse outcome?