Prognostic value of immunohistochemically detected CD44 isoforms CD44v5, CD44v6 and CD44v7–8 in human breast cancer

We investigated the expression of CD44 isoforms containing variant exons v5, v6 and v7–8 in 115 human breast cancer specimens by means of immunohistochemistry. CD44 isoforms CD44v5, CD44v6 and CD44v7–8 were detected in 56% ( n = 64), 24% ( n = 28) and 15% ( n = 17), respectively. In 36 specimens of axillary lymph node metastasis, expression of CD44v5, CD44v6 and CD44v7–8 was found in 94% ( n = 34), 92% ( n = 33) and 89% ( n = 32), respectively. Five year survival rates with or without CD44v5 and CD44v6 expression were 71% versus 86% (log-rank test, P = 0.02) and 62% versus 81% (log-rank test, P = 0.001), respectively. For disease-free survival, expression of CD44v5, CD44v6 and CD44v7–8 showed a prognostic impact (log-rank test, P = 0.004, P = 0.0001 and P = 0.0001, respectively). However, multivariate analysis revealed that all investigated CD44 isoforms failed to be independent predictors of the patient's outcome.