Source: The Endocrine Society
Exposure to dim light at night, which is common in today's lifestyle, may contribute to the spread of breast cancer to the bones, researchers have shown for the first time in an animal study.
More than 150,000 U.S. women had breast cancer in 2017 that metastasized, or spread outside the breast, according to an estimate from the National Cancer Institute.
When breast cancer spreads, it often goes to the bones, where it can cause severe pain and fragile bones.
In this preliminary study the researchers created a mouse model of bone metastatic breast cancer. They injected estrogen receptor-positive human breast cancer cells that have a low propensity to grow in bones into the tibia, or shinbone, of female mice.
Like humans, the mice used in this study produce a strong nighttime circadian melatonin signal.
This nighttime melatonin signal has been shown to produce strong anti-cancer actions and also promotes sleep
X-ray images showed that mice exposed to a light/dim light cycle had much larger tumors and increased bone damage compared with mice kept in a standard light/dark cycle, he reported.