Similar to humans, cancer is the leading cause of death among older cats. It is caused by uncontrolled cell growth, and affects a wide range of cell types and organs in the body. Feline cancer initially manifests as a lump or bump on any parts of the body. It rapidly grows in the affected cell; attaches itself to the tissue under the skin in that area; and, depending on the tumour, it can spread to other parts of the body.