Expression of CD44 standard and variant-v6 proteins in transitional cell bladder tumours and their relation to prognosis during a long-term follow-up.

The expression of the standard CD44 (CD44s) and its v6 isoform (CD44v6) was analysed immunohistochemically in 173 cases of transitional cell bladder cancer. The results of immunohistochemical analyses were related to established prognostic factors and clinical follow-up data. The expression intensity of CD44s in non-basal tumour cells was significantly related to TN classification, S-phase fraction (SPF), mitotic index, grade, density of tumour infiltrating lymphocytes. The expression intensity of CD44v6 in non-basal tumour cells was inversely related to DNA ploidy, SPF, and mitotic index. The expression intensity of CD44v6 in basal tumour cells was also inversely related to T-category, grade, papillary status, DNA ploidy, SPF, and mitotic index. Strong expression of CD44s in non-basal tumour cells was related to unfavourable outcome in univariate analysis (p = 0.008), whereas the strong expression of CD44v6 in both non-basal cells (p = 0.005) and basal cells (p = 0.0008) was related to high survival probability. In multivariate survival analysis, the expression intensity of CD44v6 was independently related to favourable outcome in muscle invasive tumours, while in superficial tumours, CD44s was an independent prognostic factor. The results suggest that the expression of CD44s and CD44v6 is associated with malignant features and prognosis in bladder cancer.