Better scientific tools have allowed researchers to learn more about inherited genetic mutations that increase risk or mutations that develop inside of the cancer cell that help fuel its growth. Breast cancer happens to have good examples of both kinds of mutations.
Mutations in the genes called BRCA1 and BRCA2 can be inherited (passed on) through the mother or the father. The BRCA genetic mutations increase the risk of breast and ovarian cancer in women, and breast and prostate cancer in men. Testing for the BRCA mutation is recommended for women and men with a strong family history of breast cancer, as it gives someone who tests positive for the mutation the opportunity to consider risk-reduction options.
Following a breast cancer diagnosis, the tumor tissue is tested to see if it carries the HER2 mutation. HER2 mutations are not inherited. They are one of the many mutations that can occur inside and help transform a normal cell into a cancer cell. Breast tumors are tested for this mutation because tumors that are HER2-positive can be treated with a HER2-targeted therapy, like Herceptin.
But that’s not the whole story. Another piece of the cancer puzzle is epigenetics—marks that can occur on top of a gene. These marks don’t change the gene’s DNA, but they can change how it functions. This means they can turn genes on that should be off, or turn off genes that should be on. Because these marks are not necessarily permanent, it is possible that scientists could find ways to return the genes into their correct on or off position.
Researchers are also studying epigenetic patterns to see if there is a relationship between certain genes being on and off and cancer risk. In June, researchers from the University of College, London, published a study in Genome Medicine about an epigenetic pattern they identified in women with a BRCA1 genetic mutation that also was found in women who had developed breast cancer but did not have a BRCA1 mutation. It is possible that a test like this might one day be used to identify women who are at high risk of developing breast cancer even though they don't have the BRCA1 mutation—and maybe even reverse what the epigenetic marks have done.
Read more about epigenetics:
University of Utah Health Sciences: http://learn.genetics.utah.edu/content/epigenetics/
Discover Magazine: http://discovermagazine.com/2013/may/13-grandmas-experiences-leave-epigenetic-mark-on-your-genes
Check out this timeline of epigenetic breakthroughs in cancer research: http://epigenie.com/epigenetics-in-cancer-timeline/