We've known for a long time that cancer cells, unlike normal cells, multiply uncontrollably, ignoring the usual signals to stop. But over the past two decades cancer research has uncovered much more.
Many factors come together to cause each type of cancer.
Genetic mistakes can be inherited or they can be acquired as a result of exposure to chemicals, radiation, or viruses. Random mistakes also occur each day in the course of duplicating the three billion units in our DNA during cell division. No one mutation is enough to make a cell cancerous. Multiple genetic changes, in specific classes of genes, are needed to transform a normal cell into a neoplastic cell that grows out of control. A small percentage of people inherit a susceptibility for certain types of cancer, putting all their body's cells one step closer to the disease.