Cancer, for the most part, is caused by multiple somatic mutations in a single cell and its progeny. However, in some individuals, constitutional genetic alterations may also play a role. Depending on the specific cell type, the affected cell and its progeny accumulate sequential mutations and sustain multiple genetic alterations over decades. The defective genetic anomalies lead to disabled critical cellular pathways, which with DNA replications in between, evolve clonally and expand into a malignant phenotype. Additional mutations in some genes confer a further selective growth advantages and the neoplastic process progresses to invade surrounding tissues and metastasise to other organs.