Ever since the finding that hormone replacement therapy may increase the risk of diseases like cancer, researchers have speculated that it may not be just the pills causing the problems.
Now scientists at Duke say they've stumbled onto a major clue...compounds in the environment and even in some medication that may alter the way the body regulates estrogen, thereby changing the way hormone replacement pills work.
"This is one piece of the puzzle an important piece we believe, and that is, people who are exposed to agents like this would be anticipated to respond differently than other people," says hormone researcher Dr. Donald McDonnell, PhD.
Duke scientists say two of those agents which may influence hormone therapy are an industrial solvent called EGME and the drug Depakote, which is prescribed for epilepsy, migraines and bipolar disorder. The thinking is that compounds in those two agents appear to rev up the activity of estrogen in breast cancer cells.
The first chemical, ethylene glycol methyl ether (egme), is an industrial solvent found in varnishes, paints, dyes, fuel additives and the semiconductor industry. The second compound -- valproic acid (trade name Depakote) -- has a similar chemical structure as egme and is among the top 100 drugs prescribed in the U.S., used to treat bipolar disorder, seizures and migraines.estrogen helps feed breast cancer tumors, but researchers say the hormone also helps boost bone growth so the compounds may have a positive effect on osteoporosis.
More study is needed, but researchers say these early findings should at least raise awareness among doctors and patients about the impact of other medicine and environmental factors when prescribing hormones, for menopause or even for birth control.
The study was conducted by researchers from the Duke Comprehensive Cancer Center and the Department of Pharmacology and Cancer Biology at Duke University Medical Center and is published in the proceedings of the National Academy of Sciences.