Neuroendocrine modulation of tumor metastases. I. Effect of adrenalectomy on B16 melanoma metastases.

: There is increasing evidence to suggest a link between the neuroendocrine system and the immune system. Since it is well known that the immune response influences the establishment, progression or elimination of malignancy, we have examined the effects of adrenalectomy on B16 melanoma pulmonary tumor metastases and immune function in C57BL/6 mice to investigate the role of adrenal corticosteroids. Adrenalectomized mice were injected with 10(5) B16 melanoma cells on day 0. On day 9 the mice were sacrificed and the number of lung colonies counted. Adrenalectomized animals had a greater than 3 to 4-fold increase in the number of metastases as compared with sham operated animals. Steroid replacement therapy using dexamethasone delivered at 1 microgram/hr did not lead to any reduction in tumor metastases in adrenalectomized animals. These studies indicate that normal levels of adrenal steroids may influence the ability of tumor cells to colonize target organs and/or the ability of the immune system to mount an effective response.