Vagus nerve regulates breast cancer metastasis to the adrenal gland

Metastasis of breast cancer to adrenal glands may alter neuroendocrine functions which increase the severity of the disease. In this study the role of vagus nerve activity in adrenal metastases was examined. 48 Balb/c mice (n=48) were divided into four groups; control, sham-operated, right vagotomy or left vagotomy. Vagotomies were performed one week before orthotopic injection of 4THM breast carcinoma cells and the degree of adrenal metastasis was assessed. In control animals, besides extensive metastases within and around the adrenal, 70% loss of medulla was observed which was significantly more than cortical loss. Sham operation by itself significantly decreased both the extent of metastases and medullary loss. Compared to sham group, vagotomy increased intra- and extra-adrenal metastasis. There was laterality in the regulation of metastasis by the vagus nerve, such that the right adrenal gland was affected the most. Vagus nerve activity may reduce adrenal metastasis as well as tumor-induced alterations of adrenal functions.