Clinical significance of definite muscle layer in TUR specimen for evaluating progression rate in T1G3 bladder cancer: multicenter retrospective study by the Sapporo Medical University Urologic Oncology Consortium (SUOC)

Purpose To evaluate the clinical impact on progression and recurrence according to presence and absence of a muscle layer, we conducted a retrospective, multicenter study. Methods We retrospectively reviewed 247 patients who received transurethral resection (TUR) of bladder tumors and were pathologically diagnosed as having T1G3 bladder cancer from 1990 to 2009. We ruled out 8 patients who received immediate cystectomy and analyzed the remaining 239 T1G3 patients. Patients who had invasion to the prostatic urethra and patients who underwent a second TUR were not included. Results TUR specimens from 194 patients were confirmed to have a definite muscle layer and those from 45 did not. The median follow-up period was 53 months, ranging from 3 to 181 months. The progression-free survival rates at 5 years after TUR were 91.1 % for patients who had a muscle layer in their specimen and 77.3 % for those who did not ( p = 0.005, log-rank test). Multivariate analysis indicated that the absence of a muscle layer was a risk factor for progression ( p = 0.006, Cox proportional hazards analysis). Conclusions Patients without a muscle layer in the specimen had high risk for progression. The initial TUR must have a muscle layer in the specimen. Variations of progression rates in previous studies might be due to different proportions of patients who had a muscle layer in TUR specimens.