Background: Few and partially contradictory data are available regarding the prognostic signature of downstaging of muscle-invasive clinical tumour stages in patients treated with radical cystectomy.
Materials and methods: Clinicopathological parameters of 1,643 patients (study group, SG) treated with radical cystectomy due to muscle-invasive urothelial bladder cancer were summarized in a multi-institutional database. Patients of the SG fulfilled the following conditions: clinical tumour stage T2 N0 M0 and no administration of neoadjuvant radiation or chemotherapy. Cancer-specific survival (CSS) rates were calculated referring to pathological tumour stages in cystectomy specimens (<pT2, pT2, >pT2) (mean follow-up: 51 months). Furthermore, a multivariable model integrating clinical information was developed in order to predict the probability of downstaging.
Results: A total of 173 patients (10.5%) of the SG presented with downstaging in pathological tumour stages (pT0: 4.8%, pTa: 0.4%, pTis: 1.3%, pT1: 4.1%); 12 of these patients had positive lymph nodes (7%, in comparison with 21% pN+ of pT2 tumours and 43% of >pT2 tumours). Patients with tumour stages <pT2, pT2 and >pT2 had CSS rates after 5 years of 89, 69 and 46%, respectively (p<0.001). In a multivariable Cox model the presence of pathological downstaging resulted in a significant reduction of cancer-specific mortality (HR 0.30; 95% CI 0.18-0.50). By logistic regression analysis the date of TURB (benefit for more recent operations) was identified as the only independent predictor for downstaging of muscle-invasive clinical tumour stages. Age, gender, grading and associated Tis in the TURB did not reveal any significant influence.
Conclusion: Patients with muscle-invasive clinical tumour stages and downstaging in cystectomy specimens represent a subgroup with significantly enhanced CSS rates. Further trials that integrate the parameters tumour size, stages cT2a vs cT2b and focality are required in order to define the independent prognostic signature of downstaging of tumour stages more precisely.