Modification of the growth rates and hypoxic fractions of xenografted A431 tumors by sialoadenectomy or exogenously supplied epidermal growth factor.

We studied A431 epidermoid carcinomas xenografted into male nude mice either in the unperturbed state or after either surgical removal of the salivary glands or i.p. injection of exogenous epidermal growth factor (0.2 mg/kg daily for 7 days). The percentage of hypoxic cells in unperturbed tumors was 10.5% (95% confidence limits, 6.6-16.8%). In mice that received epidermal growth factor injections, hypoxic percentages decreased to 3.7% (1.7-7.8%), and tumor growth rates increased. In sialoadenectomized mice, hypoxic percentages increased to 35.2% (27.1-45.6%), and tumor growth rates decreased. These data indicate that the biology of solid tumors can be significantly modified by the host status.