Cancers that can metastasize or spread to the brain and can lead to Brain Cancer include lung cancer, breast cancer, bladder cancer, kidney cancer, etc. However, the exact cause for the change from normal cells to cancer cells in both metastatic and primary brain tumors is not yet understood. Some environmental factors and genetic conditions may contribute to the development of brain cancer, but several other factors that are Brain Cancer causes cannot be overlooked. Research shows that primary brain tumors are less common than secondary brain tumors, in which cancer begins elsewhere in the body and spreads to the brain. In most cases, a brain nodule or a tumor is the result of cancer that began elsewhere in your body like the colon, breast, melanoma, etc.