A study published Friday in the journal Nature Communications found that the way people's bodies function during the day could interfere with some cancer medicines.
The researchers at the Weitzmann Institute discovered that daytime hormone production "inhibited the work of epidermal growth factor (EGF) receptors," a.k.a. the proteins targeted by some anti-cancer drugs, such as lapatinib, which is used to treat breast cancer, Time reports. The tumor cells use the receptors to "attract nutrients that help them survive," while drugs like lapatinib block the receptors. But the study found that when tumor cells that are attached to steroid hormones in addition to the receptors, some cancer drugs are less effective.
The researchers experimented on mice, treating different groups with lapatinib at various times of day. They found that the mice treated with lapatinib at night had "significantly smaller tumors" than those treated during the day. The scientists speculate that lower nighttime hormone production contributed to the drug's increased effectiveness.
More research is needed, since the researchers only tested their findings on animals, but the findings could have significance for cancer treatments in the future.