Cancer cells unlike normal cells grow out of control instead of dying off. Although there are many different types of cancer cells they all start from a cell that is growing abnormally which can start in any part of the body. Cells like these are created from reasons such as gene mutations, these mutations develop over time when people get older and genes wear out. However, genes can also be damaged from cigarettes, alcohol or ultra violet radiation from the sun. All of these substances have poisons in them which confuse the blueprint, that then creates the cancer cell, however the cancer cell continues to multiply and grow due to the blueprint being unaware of the type of cell its creating. Cancer cells might take months to spot because it keeps on developing and growing around the whole body creating tumours.