What does "clonal expansion" refer to in cancer biology?

Clonal expansion refers to the process in which a single cancer cell undergoes multiple rounds of division, resulting in the proliferation of identical daughter cells. This phenomenon is central to the development of tumors, as it creates a large population of cells that share the same genetic mutations and characteristics as the original mutated cell. When a mutation occurs in a single cell that gives it a growth advantage, that cell can rapidly divide, leading to a mass of similar cells that can outcompete normal cells and dominate the tissue environment.

This concept is fundamental in understanding how cancers grow and evolve over time. The continuous division and the accumulation of additional mutations within these identical cells can further enhance their capabilities, making the cancer more aggressive and resistant to treatment. Clonal expansion underscores the significance of genetic alterations in cancer biology and illustrates the challenges of developing effective therapies against heterogeneous tumor populations.