Epidermal growth factor receptor in human bladder cancer: a comparison of immunohistochemistry and ligand binding

Epidermal growth factor receptors were measured in biopsies from patients with newly diagnosed bladder cancer. Two methods to detect these receptors were compared: immunohistochemical staining of frozen sections, and a ligand binding study using radiolabeled epidermal growth factor and tumor cell membranes. We studied 101 patients by immunohistochemistry and 47 patients by both methods. An association was found between immunohistochemical positivity for epidermal growth factor receptors and high tumor stage (p less than 0.001). Thus, most of the muscle invasive tumors were positive (35 of 49, 71 per cent) and more stage pT1 tumors were positive (8 of 18, 44 per cent) than were stage pTa tumors (5 of 34, 15 per cent, p less than 0.05). The ligand binding study was slightly more sensitive in detecting receptors than immunohistochemistry (30 of 47, 64 per cent and 25 of 47, 53 per cent, respectively). Greater amounts of receptors were found in muscle invasive tumors compared to tumors not invading muscle (p less than 0.05). A significant association was found between the 2 methods in the detection of receptors (p less than 0.001) and no discrepancies were found between the 2 methods in tumors containing high levels of receptors. Immunohistochemistry provides a satisfactory method to detect receptors in tumors with high levels of receptors, although ligand binding is more sensitive in tumors with low levels of receptors.