New research from Tulane University points to a connection between levels of the hormone melatonin and drug resistant breast cancer.
A study published in the journal Cancer Research points to a connection between low melatonin levels and resistance to tamoxifen, a common breast cancer drug.
Melatonin is a hormone found in animals, plants, and microbes. It is produced in our pineal gland, and forms part of the system that regulates our sleep–wake cycle by chemically causing drowsiness and lowering the body temperature. Our levels of melatonin vary during the day and are biologically synchronized to our daily environmental cycle.
It is known that melatonin interacts with our immune system, is inhibited by light to the retina, and permitted by darkness. Its production decreases as we age.
A study now suggests that suppressed production of melatonin, as a result of sleeping with a light on at night, reduces the effectiveness of the breast-cancer drug tamoxifen. The researchers found that the nighttime levels of melatonin alone slowed the growth of the tumors, but when tamoxifen was also administered ahead of the period of darkness, the tumors regressed even faster.
Steven Hill, professor of structural and cellular biology and chair for breast cancer research at the Tulane University School of Medicine suggests that the timing of when breast cancer patients take their medication may be something to consider, and points out that “The FDA has no guidelines on when during the day you should take tamoxifen. So take your tamoxifen at night right before you go to bed, and I think our study suggests that melatonin will turn off a number of pathways that would prevent tamoxifen from working.”