Clonal expansion is a critical aspect of cancer evolution. It occurs when a single cancer cell acquires a mutation that gives it a growth advantage over its neighbors. This cell and its descendants proliferate more rapidly, forming a clone. As the tumor grows, additional mutations can arise within this clone, leading to the formation of subclones with distinct genetic profiles. This intratumoral heterogeneity makes the cancer more adaptable and can complicate treatment, as different subclones may respond differently to therapy.
