Normal cells divide and duplicate themselves in a very controlled way, but sometimes an error occurs, and the DNA is not copied correctly. Most of the time this error is corrected, or the cell cannot function and is destroyed. Yet sometimes the tiny change in the DNA is not repaired, and the error is passed on when the cell divides to make new cells.
If the change is a mutation that interferes with a critical function such as DNA repair or the regulation of cell growth, then the mutation can make the cells more cancer-like. If enough mutations occur within a cell over time, it can lead to cancer.
A gene mutation is a permanent change in the DNA that makes up a particular gene. For cancer, two kinds of gene mutations are important.
Random (acquired): the mistakes that occur in DNA by chance and get repeated. These mistakes are more likely to happen as people get older. Being exposed to ultraviolet radiation from the sun, or to certain chemicals or environmental elements, can also make random genetic changes more likely.
Inherited: the genetic changes that a person is born with, usually passed on by the person’s father or mother or both.
Most cancers develop from random mutations, but up to 10% come from inherited genetic changes passed on by a parent. Certain inherited mutations can make it much more likely that a person carrying the mutation will get cancer—and will get cancer earlier.
If you do carry an inherited mutation that has been linked to cancer, knowing your risk can help you and your doctor make better, more informed decisions about your health, possibly before cancer has a chance to develop. It can also help you protect your children and other family members.