Tumors May Grow Faster at Night: New Schedule for Cancer Treatments

It turns out that tumors don't grow continuously. Instead, they seem to prefer to emerge at night. Scientists have found that nighttime is when cancerous tumors tend to spread in the body, which could have implications when it comes to administering certain treatments.

The researchers stumbled upon the finding while investigating the relationships between different receptors in the cells. The receptors, which are protein molecules on the cell's surface or within cells, take in biochemical messages that are secreted by other cells and pass them into the cell's interior.

During the study, the scientists focused on two particular receptors. The first one, called the epidermal growth factor receptor, EGFR, promotes the growth and migration of cells, including cancer cells. The second receptor binds to a steroid hormone called a glucocorticoid (GC). Glucocorticoids play a role in maintaining the body's energy levels during the day.

The scientists checked the activity levels of the receptors in mice. With multiple receptors, the cell receives many messages at once, and some of these messages take precedence over others. In this study, the scientists found that cell migration, which is promoted by the EGF receptor, is suppressed when the GC receptor is bound to the steroid messenger. Then, the researchers tested to see how the second receptor, EGFR, might be affected. Surprisingly, they found that the EGFR is much more active during sleep. The finding could be huge in terms of understanding cancers that use the EGF receptors to grow and spread.

"It seems to be an issue of timing," said Yosef Yarden, one of the researchers, in a news release. "Cancer treatments are often administered in the daytime, just when the patient's body is suppressing the spread of cancer on its own. What we propose is not a new treatment, but rather a new treatment schedule for some of the current drugs."

The findings are published in the journal Nature Communications.