The influence of immunosenescence on tumor growth and spread: lessons from animal models.

There has been a long-standing clinical impression that tumor grow more slowly in elderly patients, but, because of confounding variables, this impression has been difficult to substantiate by epidemiologic data. Animal models offer a way to explore the relationship between host age and tumor growth under more controlled conditions. Our studies with murine B16 melanoma xenografts, discussed here, show that tumor growth and spread is in fact reduced in older animals and suggest that age-associated changes in immune function may be partially responsible.