Final answer:
Tumors evolve through a multi-step process known as carcinogenesis, which involves mutation, proliferation, and natural selection, transforming normal cells into cancer cells. This process results in cell populations that can metastasize and is influenced by various carcinogens.
Step-by-step explanation:
Tumors evolve by repeated rounds of mutation, proliferation, and natural selection - otherwise known as carcinogenesis.
Carcinogenesis, also referred to as oncogenesis or tumorigenesis, is the process by which normal cells are transformed into cancer cells.
This transformation is a multi-step event that begins with a single cell acquiring a mutation that prevents appropriate cell death, leading to unregulated cell growth.
Further mutations within the rapidly dividing cells select for even more aggressive cell behavior, creating a tumor that grows and can ultimately become malignant.
During these stages, proto-oncogenes may be activated to become oncogenes, and tumor suppressor genes may be inactivated, which contributes to the cancerous state of the cells.