Background: The infiltration of muscularis mucosa in superficial bladder cancer has been reported to be predictive of an unfavourable course of the disease.
Materials and methods: We studied immunohistochemically Ki-67, PCNA and p53 tumour markers in 68 P1a and Pib bladder tumours.
Results: A statistically significant difference (p = 0.01) was found in the distribution of grades between stages P1a and P1b, with more grade 3 and less grade 2 tumours in the latter category. Univariate analysis revealed a strong association of Ki-67 (p = 0.001) and PCNA (p = 0.032) only with stage. P53 protein expression did not have any significant association with either stage or grade. In 60 patients entered into the multivariate analysis a clearly predominant, significant effect of stage on Ki-67 (p = 0.000) was shown.
Conclusion: Increased proliferative activity when compared to P1a is present in P1b bladder tumours, as detected by the increased expression of Ki-67 proliferating antigen. The immunohistochemical study of Ki-67 antigen may help in predicting stage P1 tumours' behaviour, even in cases where pathological distinction of P1a and P1b substages is difficult.