Cancer Cancer is a class of diseases caused by loss of cell cycle control. 8. In animals, cell numbers are under exquisite control Loss of this control leads to proliferation of unwanted cells .8 Cancer arises when the above situation reaches a certain degreeCancer is a class of diseases caused by loss of cell cycle control. Cancer ❖ In animals, cell numbers are under exquisite control ❖ Loss of this control leads to proliferation of unwanted cells ❖ Cancer arises when the above situation reaches a certain degree