Cancers begin when genetic mutations occur in cells of a specific organ. These mutations may be inherited from parents, and include the BRCA1 and BRCA2 gene mutations. However, there are other gene mutations that can cause cancer in other organ systems. As it turns out, different gene mutations tend to be specific to causing cancers in a particular organ. However, there is a fair amount of overlap, so that a gene mutation like BRCA1 or BRCA2 which usually causes cancer in breast, ovary and uterine tissue may also cause an increased risk for colon cancer, or pancreatic cancer. This concept of ‘Genetic Overlap’ is the foundation for the current model of cancer development, where certain gene mutations may increase the risk for cancer in several organ systems.