Expression of pS2 protein in transitional cell bladder tumours.

A series of 201 bladder cancer biopsy specimens was analysed immunohistochemically for the expression of pS2 protein. Altogether, 61 per cent of the tumours were pS2-negative; in 16 per cent less than 1 per cent and in 23 per cent of cases more than 1 per cent of cells were pS2-positive. Normal transitional epithelium was negative for pS2. The fraction of positive cells was higher in poorly differentiated non-papillary tumours and in invasive tumours with pelvic lymph-node (P = 0.05) and distant metastasis (P = 0.10). pS2 expression was not related to sex, while patients aged 60-70 years had low fractions of pS2-positive cells (P = 0.03). DNA ploidy, S-phase fraction, mitotic index, morphometric nuclear features, and expression of c-erbB-2, p53, and epidermal growth factor receptor were independent of expression of pS2. Tumours expressing pS2 in over 10 per cent of cells had a lower survival probability (P = 0.0486). The results show that pS2 is expressed in 40 per cent of transitional cell bladder tumours, but that this marker has no clinical significance over established prognostic factors.