Disability is lack of ability related to a personal or group standard or norm. In reality there is often simply a spectrum of ability. Disability may involve physical impairment, sensory impairment, cognitive or intellectual impairment, mental disorder (also known as psychiatric or psychosocial disability), or various types of chronic disease. A disability may occur during a person's lifetime or may be present from birth.

Cancer may affect people at all ages, even fetuses, but the risk for most varieties increases with age. Cancer causes about 13% of all deaths. According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007.