OBJECTIVE Tissue polypeptide antigen (TPA) is a differentiation and proliferation tissue marker of epithelia. Increased serum levels were found in some patients with invasive bladder cancer. We present the results of a prospective study that evaluated the role of serum TPA (S-TPA) in bladder carcinoma. METHODS The series included 167 patients treated for invasive bladder cancer between 1989 and 1996. S-TPA concentrations were measured by radioimmunoassay before treatment, at the end of treatment, and during follow-up evaluation. The upper normal limit of the test was set at 80 UI/L. RESULTS With a specificity of 100%, the diagnostic sensitivity was 46%. Pretherapeutic S-TPA levels were significantly correlated with tumor stage (T2 v T3 and T4; P = .02), with nodal stage (N0 v N1 and N2; P = .00001), and with metastatic stage (M0 v M1; P = 10[-6]), but not with histologic grading (grade 1 and 2 v 3). In the subset of patients with normal pretherapeutic S-TPA levels, 95% had no residual disease at the end of treatment, compared with 53% of patients with initial elevated S-TPA (P = 10[-8]). Among patients who achieved a complete response, 27% experienced a relapse, with an increase of S-TPA in 72% of cases. The mean follow-up time was 20 +/- 17 months. For patients with normal pretherapeutic S-TPA levels, 3-year overall survival and disease-free survival rates were 76% and 67% respectively. These were 46% (P = .001) and 25% (P = 10[-7]), respectively, for patients with high pretherapeutic S-TPA. Multivariate analysis showed that S-TPA was an independent prognostic factor for survival (P = .03). CONCLUSIONS In invasive bladder cancer, S-TPA level is correlated with initial tumor stage. It is a valuable parameter for follow-up evaluation and appears to be a prognostic factor in multivariate analysis.