Cancer is a genetic disease—that is, cancer is caused by mistakes in genes, called mutations, that control the way our cells function, especially how they grow and divide. Cancer begins when the cell starts to grow and divide out of control.
Cancer is common and many families have at least one or a few members who have had cancer. One in three individuals will develop cancer in his/her lifetime.
Most cancers are sporadic, which means they occur by chance.
However, in some families, genetic changes that increase cancer risk can be inherited from our parents. This is the case in only 5 to 10 percent of all cancers.