Cats as pets

In captivity, indoor cats typically live 14 to 20 years, though the oldest-known cat lived to age 36.[44] Domesticated cats tend to live longer if they are not permitted to go outdoors (reducing the risk of injury from fights or accidents and exposure to diseases) and if they are spayed or neutered. Some such benefits are: neutered male cats cannot develop testicular cancer, spayed female cats cannot develop ovarian cancer, and both have a reduced risk of mammary cancer.

Source : http://en.wikipedia.org/wiki/Cat#Feral_cats