Cancer is a diverse group of diseases characterized by uncontrolled growth of abnormal cells. Cancercells grow abnormally because of damage to their DNA. This DNA damage garbles the genetic signals for normalgrowth. The molecular approach to cancer gets to the heart of the matter. Molecular studies have uncoveredmany of the details whereby a normal cell becomes cancerous. These discoveries have revealed cancer to bea multi-step process, involving the progressive loss of control by the malignant cell, failure of DNA repair, andloss of backup systems for preventing abnormal cell growth. The process of neoplasia is a result of stepwisealterations in cellular function. These phenotypic changes confer proliferative, invasive, and metastaticpotential that are the hallmarks of cancers.