We all have variations in the genetic code which is why we are all unique. Most variations are harmless. However, variations to the genetic information can sometimes make the gene faulty which means that a particular protein is not produced properly, produced in the wrong amounts or not produced at all.
Variations that make the gene faulty are called mutations.
For example: If “The cat ate the rat” is a genetic code and a mutation causes one letter to be missing, “Thc ata tet her at” has lost all meaning.
Genetic damage causes cancer
Cancer is caused by changes to genes that control the way cells function, grow and divide. As part of the aging process, DNA gets damaged and the cell either repairs the damage or the cell dies. In cancer cells, the damaged DNA is not repaired and the cell does not die and continues to grow and form new, abnormal cells. These cancer cells can also invade (grow into) other tissues, something that normal cells cannot do.
The factors that are associated with an increased risk of cancer cause this DNA damage. Most cancers occur in older people and are part of the aging process. However smoking, alcohol, ultraviolet light damage and an unhealthy diet will also result in damage to our DNA.
The greatest risk factor for breast and ovarian cancer is inheritance of a mutation in one of the breast cancer susceptibility genes, BRCA1 & BRCA2.