"A breast cancer therapy that blocks estrogen synthesis to activate cancer-killing genes sometimes loses its effectiveness because the cancer takes over epigenetic mechanisms, including permanent DNA modifications in the patient's tumor, once again allowing tumor growth, according to researchers.
The findings of this international team, headed by the University of Pittsburgh Cancer Institute (UPCI) in Pennsylvania, warrants research into adding drugs that could prevent the cancer from hijacking patients' repressive gene regulatory machinery, which might allow the original therapy to work long enough to eradicate the tumor. The study was published in Science Translational Medicine (2014; doi:10.1126/scitranslmed.3008326).
"Our discovery is particularly notable as we enter the era of personalized medicine," said senior author Steffi Oesterreich, PhD, of UPCI. "Resistance to hormonal therapy is a major clinical problem in the treatment of most breast cancers. Through testing of a tumor's genetic and epigenetic make-up, we may be able to identify the patients most likely to develop such resistance and, in the future, create a treatment regimen tailored to giving each patient the best chance of beating their cancer."
Epigenetic translates to above genetic and is an emerging field of study that looks at how environmental factors such as infections, pollutants, stress, and in this case, long-term exposure to drugs that block estrogen synthesis, could influence a person's DNA. Epigenetic changes do not alter the structure of the DNA, but they do change the way the DNA is modified, which subsequently determines the potential of gene regulation."