Epidermal‐growth‐factor‐receptor expression is associated with rapid tumor proliferation in bladder cancer

Epidermal‐growth‐factor‐receptor (EGF‐r) expression has been proposed as a prognostic marker in bladder cancer and is associated with rapid proliferation in cell lines. Ninety‐three fresh and 74 formal in‐fixed bladder tumors were examined by fluorescence in situ hybridization (FISH) and immunohistochemistry to assess the relationship between EGF‐r expression and proliferation as well at the prevalence of epidermal‐growth‐factor‐receptor (EGF‐r) gene amplification. EGF‐r expression was strongly associated with BUdr labeling index, grade and stage. EGF‐r expression emerged as a stronger predictor of tumor proliferation than grade or stage in analysis of variance. Rapid tumor proliferation might be responsible for bad prognosis reported in EGF‐r positive bladder tumors. Also chromosome 7 copy number was associated with grade and stage. EGF‐r gene amplification was uncommon (5 of 107 tumors). However, FISH analysis allowed characterization of the pattern of amplification, with clustering of signals suggestive of intrachromosomal amplification more common than diffuse distribution consistent with extrachromosomal amplification. © 1994 Wiley‐Liss, Inc.