I read the following online: Metastasis is the process where cancer breaks out from where a tumour has initially grown and spreads to other parts of the body. It is usually the reason why cancer is fatal. Now if the cancer would'nt spread then would'nt it still be fatal as the place where the cancer started, would eventually become a tumor. Also is the reason that the spread of cancer fatal because tumors will form at multiple locations throughout the body? And why exactly is a tumour bad for health?