Unique patterns of brain metastasis produced by different human carcinomas in athymic nude mice.

The purpose of this study was to develop an in vivo model to study the growth pattern and biological behavior of brain metastases produced by different human carcinomas. To do so, human tumor cells from 8 different carcinomas of the colon, breast, kidney and lung were injected into athymic nude mice either by a direct intracerebral route or into the internal carotid artery. All carcinoma cells invaded through the blood-brain barrier and produced progressively growing lesions in the brain parenchyma. Unique patterns of growth were discernible among the carcinomas. Human colon carcinomas produced multiple lesions that spread by extension. Lung carcinoma cells produced widespread lesions throughout the brain. A very high degree of vascularization was associated with lesions produced by renal-cell carcinoma. The influence of estrogen on the growth of estrogen-receptor-positive human breast carcinoma cells was well demonstrated in this model. We conclude that the athymic nude mouse can be a useful model for studies of the biology and perhaps therapy of brain metastases produced by human carcinoma cells.